Traction Aiding Devices Frequently Asked Questions (TADFAQ)

Although the Detroit Locker and the PowerTrax LockRight effectively do the same think, their fysical design is quite different. John Barron wrote the following on the TLC Mailinglist:

 
To:               LandCruisers@tlca.org
Send reply to:    LandCruisers@tlca.org
Date sent:        Sat, 5 Apr 1997 21:26:13 -0800
From:             jbarron@uvic.ca (John Barron & Lori Hryniuk)
Subject:          Detroit vs LockRight (was: Auburn LSD or ARB) 

>> Personally, If I were to do it again, I would go with Detroits front and
>> rear. Things of beauty, put LockRights to shame, and have none of the "side
>> benefits" of ARBs.
>
>  Detroits are certainly more *expensive* than LockRights; what makes
>them better?  My understanding is that they are somewhat heavier
>duty, but I would think that that would only be an issue with a
>fire-breathing engine.

Mike:

The LR and the Detroit are kind of the same thing in that they are both
"automatic" lockers but the way in which they operate is quite different.

You really should take a look at the two units to get a good idea of what I
am talking about as any explanation I try to make will not be sufficient.
(These should be on display at a FourWheel Drive shop if there is one near
you.) Just trust me that there is a really good reason for the extra cost
of the Detroit unit.

The basic differences are:

The Detroit is inherently stronger than the LR by design. In the LC the
Detroit replaces the whole carrier with a stronger unit.

The Detroit use a camming action to release the dog teeth. The camming
action is "positve" in that the dog teeth are either disengaged or
engaged--it "clicks" between these two positions and there is no midway
point.

There is no rubbing of the teeth in the Detroit as in the LR. The LR uses a
"camming" action that cocks the two centre pieces around the centre pin to
disengage the dog teeth on one side. The dog teeth then rub over each other
and since they are cocked at an angle to one another they cannot re-engage.

The dog teeth on the Detroit are much bigger and more deeply cut than the
LR (like proper dog teeth should be) and they are very slightly undercut
(stay engaged when power is applied). The dog teeth are not prone to wear
in the Detroit. The main reason that LockRights "wear out," as far as I
have seen, is that the teeth chip or wear very slightly and will not stay
engaged. As the dog teeth on the LR are quite shallow this can mean that
there is not a lot of lifespan in certain applications.

The only real drawback to the Detroit is that in a semi-floating
application the lowest gear ratio that can be used is 4.11:1 due to the
centre pin design. (too bad, guess I need FF axles).

I guess the real question here is cost. If you can afford Detroits
(remember you have to remove the diff to do it) *get them*.  If you can't
and you want a locker then get a LR... The Detroit will drive more smoothly
on-road than the LR but with a bit of practice you won't see too much
difference.

Need more info? just ask!

jbarron@uvic.ca

To:               Offroad@off-road.com
Date sent:        Fri, 30 May 1997 16:01:58 +0100 (WET DST)
From:             w.j.markerink@a1.nl (Willem-Jan Markerink)
Subject:          Re: Mechanical Lockers in Reverse
Send reply to:    Offroad@off-road.com

In article <338DD262.5F2A@cts.com>, Jerry Bransford  wrote:
>Willem-Jan Markerink wrote:
>> 
>> In article <33885d6d.151936958@news.shore.net>, mjk@nospamshore.net 
wrote:
>> >This is my stupid question for the day:
>> >
>> >Do the so-called "automatic" mechanical differential lockers (like the
>> >Detriot Locker and LockRite) work when the vehicle is in reverse?
>> >
>> >--mjk--
>> 
>> Yep, and even better: also downhill with engine braking!....:-))
>> All torque/locking effects are fully reversible.
>
>True, but several recent magazine "Tech Support" columns have stressed
>that they're not NEARLY as strong in reverse and they can break if
>stressed while in reverse.

Never heard that before, I will cc'd this to the OffRoad Mailinglist.
What they might have confused is the strenght of the helical gears, their 
design is inherently less strong in the other direction.
I also believe this is a reason why current reverse gears are numerically 
lower (faster, less torque to the wheels) than 1st, while the very first 
automobiles had numerically higher reverse gears. I think this relates to 
the fact that helical gears have not been used in early diff's.
Anyone know for sure?

One should also keep in mind that LockRights are not as bulletproof as 
Detroits....for more details see the FAQ on my homepage, where John Barron 
wrote a nice description:
http://www.a1.nl/phomepag/markerink/main_4x4.htm

--
Bye,

Willem-Jan Markerink

      The desire to understand
is sometimes far less intelligent than
     the inability to understand


[note: 'a-one' & 'en-el'!]





To:               Offroad@off-road.com
From:             "Willem-Jan Markerink" 
Date sent:        Thu, 9 Oct 1997 10:27:31 +0000
Subject:          Re: Lockrights
Send reply to:    Offroad@off-road.com

On  8 Oct 97 at 11:16, Whatley,Mark wrote:

> Willem-Jan Markerink wrote:
> > 
> > On  8 Oct 97 at 6:25, mike@headwaters.com wrote:
> > 
> > >   I've been giving this some thought.  Although I have
> > >   never seen the guts of a lockright in person, I've seen
> > >   diagrams, and as near as I can figure it should actually
> > >   be freewheeling the inside wheel, not the outside wheel.
> > 
> > Wrong. The inside wheel is driven, the outside wheel is allowed to
> > freewheel faster than the ring gear.
> > This equals a gear ratio change to the worse as well, and some people
> > complain about this when towing on hill roads. Had it been the other
> > way around, they would have praised it....:-))
> 
>    This is a pretty silly complaint. 

No it is not. I not even invented it myself.

> I often tow heavy loads in
> steep mountains on winding roads. I have never even noticed any
> discernable effect from this. And I certainly don't have power to spare
> in these situations either. It would only be even potentially a concern
> on the tightest and steepest of turn, with marginal gearing and an
> underpowered vehicle in any case. Actually, this is the first time I
> have 
> ever heard this issue raised, and it does't seemto be much of a concern
> at 
> that. 

You were on the ORML many moons ago when this was discussed Mark, a
copy of that article is in my FAQ, and it involves a first hand
'complaint'. 
http://www.a1.nl/phomepag/markerink/main_4x4.htm

> I have to wonder just who these "some people" are, how many have
> voiced 
> this complaint, just what their primary uses of their vehicles are, and
> what 
> their experience and knowledge levels are.

It *is* a gear ratio to the worse, no matter whether it affects you, 
or whether you can notice at all it in ordinary use. Your defense of 
'suffient' power only backs it up. 

> > >   As I said, this is just something I'm mulling over, not a
> > >   statement of fact, but basically the lockright gears mesh
> > >   until enough twisting force is encountered to overcome
> > >   the spring tension pushing the gears together.  There is
> > >   only enough play in the system for one axle to uncouple,
> > >   so the other axle is going to be turning at the speed of
> > >   the driveshaft; that is a certainty, but which axle would
> > >   uncouple?  Does anyone know for *sure*?  Why would the
> > >   outside uncouple rather than the inside?  Does it work
> > >   the opposite way in reverse (i.e. if reversing around a
> > >   curve does the inside uncouple?)
> > 
> 
> > Yes, same as with going downhill....would be scary otherwise.
> 
>    Wrong.

Sorry, I ment that it 'worked', ignoring Mike's last sentence.
It still will uncouple the outside wheel, and the rule of 'wheel 
allowed to run faster than the ring gear, but never slower, still 
applies'.

>   No it doesn't uncouple the inside wheel when in reverse. If it did,
> then it could not function to enhance traction in the first place. It
> works the same going forward or backward. It's just folks who have never
> had one in their hands, don't understand how they work, and have never 
> even used one for that matter who keep that story alive. 

Back off Mark, I don't need to have one in my hands to evaluate the
technical nature of the beast. We beat this to death before, and I
have no intention to repeat that thread. I did not jump on your
throat on your error about the LSD availability, I expect the same
in return. 

>   In an engine braking situation, where the power is flowing from the
> wheels, it will unlock a wheel which turns slower than the other. So in
> this case it would unlock the inside wheel on a turn (assuming both
> tires had traction, and were turning properly). But it will only do this
> in the situation just described. This IS NOT at all the same as the
> engine powering the wheels in reverse. 

I dare you to explain the cause of this difference.
AFAIK the locking mechanism doesn't know in what direction it turns,
it only senses direction of torque, so be my guest to explain how it
distincts between engine braking down hill vs engine power in
reverse uphill, where the physics inside are identical, with the
exception of direction of rotation.

> If the engine is powering the
> wheels, uphil, downhil, forward or backward it is all the same. One tire
> can freewheel faster than the diff wants to push it, but neither can go
> slower. In an engine braking situation under marginal tracion, the wheel
> which is provideing the most resistance to the engine (the one with the
> best traction) will be firmly locked. The other wheel will be locked as
> long as it does not actually loose traction and slide. Then it can
> unlock until it gains traction again, at which time it will lock again.

I stick to my 'inside wheel locked until sufficient slip occurs'
scenario in all cases, unless proven *and* explained otherwise.

CC to ORML.

-- 
Bye,

Willem-Jan Markerink

      The desire to understand 
is sometimes far less intelligent than
     the inability to understand


[note: 'a-one' & 'en-el'!]




To:               Offroad@off-road.com
From:             "Willem-Jan Markerink" 
Date sent:        Fri, 10 Oct 1997 14:31:06 +0000
Subject:          Re: Clutch MC/SC, Autolockers, Steering wander
Send reply to:    Offroad@off-road.com

On 10 Oct 97 at 7:38, mike@headwaters.com wrote:

> Regarding: Autolockers
> 
> >This equals a gear ratio change to the worse as well, and 
> >some people complain about this when towing on hill roads. 
> >Had it been the other way around, they would have praised 
> >it....:-))
> 
>   I can see this for really tight turns; I mean, you could 
>   halve your torque on a tight turn in a parking lot, but I 
>   don't see it being an issue on-road.

You can never halve your torque, unless the radius of your inside 
wheel is half that of the center of your axle....8-))
It depends on wheel base obviously, since the shorter the vehicle, the 
tighter your turn is at full steering lock. It also depends on track 
width btw, the wider the worse. 
And before someone claims this never occurs on road when towing....I 
have yet to encounter a hairpin road where I *don't* smack the wheel 
from steering lock to steering lock. And I would curse any gear ratio 
change to the worse, even an otherwise 5-10% change can force you to 
an otherwise unnecessary downshift. And real men use a stick, not an 
auto that helps them out here....;-))

I still don't buy the 'outside wheel coupled' scenario when engine 
braking down hill. That would be a gear ratio change to the better, 
considering the above math.
And the diff has no way of knowing in which direction it turns 
(unless there is a magical connection between carrier and axle 
housing telling it so), it only knows in which direction the torque 
flows. There is *no* difference between engine braking downhill and 
backing up in your tracks in reverse. In both cases the coupled wheel 
will be the inside one.
Please try to convince me otherwise, but only with *good* 
arguments.

-- 
Bye,

Willem-Jan Markerink

      The desire to understand 
is sometimes far less intelligent than
     the inability to understand


[note: 'a-one' & 'en-el'!]





To:               Offroad@off-road.com
From:             mike@headwaters.com
Date sent:        Sat, 11 Oct 1997 05:50:00 +0000
Subject:          Re: Clutch MC/SC, Autolockers, Steering wander
Send reply to:    Offroad@off-road.com

Willem-Jan Markerink on Re: Clutch MC/SC, Autolockers, Stee:

> >   I can see this for really tight turns; I mean, you could 
> >   halve your torque on a tight turn in a parking lot, but I 
> >   don't see it being an issue on-road.
> 
> You can never halve your torque, unless the radius of your inside 
> wheel is half that of the center of your axle....8-))

  Sure you can.  At least, you can halve the effect of what torque 
you have.  On a sufficiently tight turn the inside wheel will 
travel only half the distance that the center of the rear of the 
vehicle will travel.  This will be equivalent to halving the numeric 
ratio of the drivetrain as compared to an open differential.

> I still don't buy the 'outside wheel coupled' scenario when engine 
> braking down hill. That would be a gear ratio change to the better, 
> considering the above math.

  Consider that the axle unlocks when there is no torque.  During 
engine braking the engine is holding back the wheels.  Torque would 
be reduced by reducing the speed of the wheels.  The wheel that turns 
slower has less torque. The wheel that has less torque uncouples.  
The inside wheel turns slower therefore the inside wheel uncouples.

> Please try to convince me otherwise, but only with *good* 
> arguments.

How did you like the ones above?  The easiest way to think about it
is to decide what the 'rest' condition is; is the system
accelerating or deaccelerating?  If it's accelerating then
drivetrain load can be reduced by the engine speed dropping or the
wheel speed increasing.  If the system is deaccelerating then the
torque can be reduced by the engine speed increasing or the wheel 
speed decreasing.  So... during acceleration (or even just overcoming 
the force of friction / wind resistance) the fast wheel lowers 
drivetrain load and therefore uncouples.  During deacceleration the 
slow wheel lowers drivetrain load so that axle uncouples.

  Accelerating: outside uncouples.
  Deaccelerating: inside uncouples.

 /---------------------------------------------------/
  Mike Graham, TLCA #5047             Ontario, Canada
  , 
  1981 BJ42 24V Diesel Land Cruiser "The Chew Toy"
  Find the ORDFAQ at 
  Diesel Technical LandCruiser list - 




To:               Offroad@off-road.com
From:             mike@headwaters.com
Date sent:        Sun, 12 Oct 1997 13:11:34 +0000
Subject:          Re: Coupled wheel on Diffs
Send reply to:    Offroad@off-road.com

wasserman on Coupled wheel on Diffs:

> On all the Lockers I have seen the way the wheel uncouples is by
> overriding the gears (going faster than the ring & pinion). The outside
> wheel in a turn has to be the one to do this because it has more
> distance to travel. It doesn't matter if you are going forward or
> backward, uphill or downhill, the same principal applies. That is the
> way a locker works. It locks the two wheels together and lets one go
> faster than that to save a little on tire costs.

  But it doesn't just 'let the wheel go faster' because if it did 
that then engine braking wouldn't work (i.e. you could roll forwards 
with the tranny in gear and the engine shut off).  What it does is 
allow one (and only one!) axle to uncouple.  It uncouples when there 
is no torque, and generally speaking this only happens when a wheel 
tries to turn faster than the diff carrier.  The exception is engine 
braking where the torque is reversed and the uncoupling still occurrs 
on the wheel with no torque, but in this case it's the slow wheel, 
not the fast wheel, so it's the inside wheel that uncouples.

  An interesting question, which hopefully Mark Whatley will notice 
and answer, is what happens if you engine brake into a turn, which 
uncouples the inside wheel, then you stomp on the gas, or even just 
apply easy throttle.

 /---------------------------------------------------/
  Mike Graham, TLCA #5047             Ontario, Canada
  , 
  1981 BJ42 24V Diesel Land Cruiser "The Chew Toy"
  Find the ORDFAQ at 
  Diesel Technical LandCruiser list - 





To:               Offroad@off-road.com
From:             "Willem-Jan Markerink" 
Date sent:        Sun, 12 Oct 1997 19:24:59 +0000
Subject:          Re: Clutch MC/SC, Autolockers, Steering wander
Send reply to:    Offroad@off-road.com

On 11 Oct 97 at 5:50, mike@headwaters.com wrote:

> Willem-Jan Markerink on Re: Clutch MC/SC, Autolockers, Stee:
> 
> > >   I can see this for really tight turns; I mean, you could 
> > >   halve your torque on a tight turn in a parking lot, but I 
> > >   don't see it being an issue on-road.
> > 
> > You can never halve your torque, unless the radius of your inside 
> > wheel is half that of the center of your axle....8-))
> 
>   Sure you can.  At least, you can halve the effect of what torque 
> you have.  On a sufficiently tight turn the inside wheel will 
> travel only half the distance that the center of the rear of the 
> vehicle will travel.  This will be equivalent to halving the numeric 
> ratio of the drivetrain as compared to an open differential.

Tell me the the tightest steering radius you have ever seen on a 
vehicle, and I will prove you that it won't even come close to 100% 
difference between inside wheel radius and center of axle radus.

Note that this only applies when the pivoting center of the axle
radius is at 'half the axle' distance from your inner wheel. That is
a pretty tight turn in my book. 
Now I ponder about it, I am not even sure whether a longer wheelbase 
increases or decreases this effect....I think it does the opposite of 
what I said earlier, ie a longer wheel base increases this change of 
ratio....thanks for this brain cracker....8-))

> > I still don't buy the 'outside wheel coupled' scenario when engine 
> > braking down hill. That would be a gear ratio change to the better, 
> > considering the above math.
> 
>   Consider that the axle unlocks when there is no torque.  During 
> engine braking the engine is holding back the wheels.  Torque would 
> be reduced by reducing the speed of the wheels.  The wheel that turns 
> slower has less torque. The wheel that has less torque uncouples.  
> The inside wheel turns slower therefore the inside wheel uncouples.

Sorry, can't follow you here....the inside wheel during engine 
braking sees more torque than the outside wheel, just as it would 
uphill. More torque pro rotation, because of less travel for the same 
amount of energy.

> > Please try to convince me otherwise, but only with *good* 
> > arguments.
> 
> How did you like the ones above?  The easiest way to think about it
> is to decide what the 'rest' condition is; is the system
> accelerating or deaccelerating?  If it's accelerating then
> drivetrain load can be reduced by the engine speed dropping or the
> wheel speed increasing.  If the system is deaccelerating then the
> torque can be reduced by the engine speed increasing or the wheel 
> speed decreasing.  So... during acceleration (or even just overcoming 
> the force of friction / wind resistance) the fast wheel lowers 
> drivetrain load and therefore uncouples.  During deacceleration the 
> slow wheel lowers drivetrain load so that axle uncouples.
> 
>   Accelerating: outside uncouples.
>   Deaccelerating: inside uncouples.

As such it doesn hold, reversing uphill and slowing down while doing 
so also counts as deaccellerating....and we don't dispute the fact 
that in this case the inside wheel is coupled....8-)) 

Also consider what happens if you stall your vehicle downhill while
engine braking, all in gear. Now do the same not in forward gear
coupled, but in reverse gear, in a perverted way of trying to slow
down more (sick to do in a manual, with a heavily slipping clutch,
but we are experimenting, right?....one *can* do this pretty easily
in an auto....a trashed auto on a Dutch military track several years
back is the silent evidence of this abuse....8-))....anyway, after 
stalling you start in gear again, reversing uphill....would the 
coupling switch from outside to inside? Uphill it *must* the inside, 
we don't dispute that. But I can't see how it would switch from 
outside to inside under such a huge load. Would be pretty scary.
I know, very hypothetically, but still.

Note that I am not convinced that *my* theory is right, but none of 
what I have seen thusfar is good enough to be included in the
FAQ....and just saying that it does it so-and-so isn't enough in my 
book....8-))

-- 
Bye,

Willem-Jan Markerink

      The desire to understand 
is sometimes far less intelligent than
     the inability to understand


[note: 'a-one' & 'en-el'!]





To:               Offroad@off-road.com
From:             mike@headwaters.com
Date sent:        Mon, 13 Oct 1997 06:01:58 +0000
Subject:          Re: Clutch MC/SC, Autolockers, Steering wander
Send reply to:    Offroad@off-road.com

Willem-Jan Markerink on Re: Clutch MC/SC, Autolockers, Stee:

> Tell me the the tightest steering radius you have ever seen on a 
> vehicle, and I will prove you that it won't even come close to 100% 
> difference between inside wheel radius and center of axle radus.

  My Ford Jubillee tractor will turn in a 10' circle and the rear 
wheels are on 6' centers.  My neighbour's skid-steer BobCat will turn 
in place (no forward motion).  Not really what you were looking for, 
eh?  Okay, that $100,000 CJ7 that was in the Tough Truck Challenge 
this year (with the gamma-goat suspension) has a turning radius of a 
hair over 25'.  A stock Unimog has a turning radius of 33'.  The FJ40 
in the TTC had a radius of 35.92'.   For the inner wheel rolling 
distance to be half the axle center rolling distance it would 
certainly have to turn pretty tight.  I might have overstated on the 
100% thing.  Maybe 50% is closer to the mark.

> Sorry, can't follow you here....the inside wheel during engine 
> braking sees more torque than the outside wheel, just as it would 
> uphill. More torque pro rotation, because of less travel for the same 
> amount of energy.

  The simple solution here is to find a guy with a spool and have him 
make low-speed turns and see which wheel skids under various 
conditions.  The wheel that skids is the wheel with the most torque 
applied.  Failing that, consider the following:

 Get yourself a ruler or some other 'shaft' with a flat or at least 
non-round section.  Hold out your left hand.  Make a fist.  Your arm 
is the driveshaft and your fist is the ring and pinion.  Hold the 
ruler or whatever you're using for an 'axle' in your fist loosely 
with your other hand holding the other end of the 'axle' so that it 
won't drop.  Now we're going to simulate torque.  It's acceleration.  
The ring and pinion are turning forward, and must 'push' the axle 
which would prefer to lag behind.  This creates a bind in the 
drivetrain.  Twist your fist forward a bit to simulate the 'bind'.  
The axle doesn't want to move outwards if you pull gently on it.  If, 
however, it turns forward a bit, it can be removed easily from your 
loosely held fist.  It's this slack that allows the locker to 
uncouple when the wheel tries to move faster than the carrier.
  Okay, now we're going to try to simulate engine braking.  Instead 
of twisting your fist forward you're going to twist the *axle* 
forward, because now the diff is trying to move *slower* than the 
axle, instead of *faster*.  The drivetrain has bind again, and the 
way to make the axle easy to remove is to turn it *backwards* i.e. 
slow it down, which creates the slack for uncoupling.

  Did that help?  At all?

> As such it doesn hold, reversing uphill and slowing down while doing 
> so also counts as deaccellerating....and we don't dispute the fact 
> that in this case the inside wheel is coupled....8-)) 

  How are you slowing down?  Via gravity or via engine braking?  If 
you're engine braking in reverse up a hill then I would say the 
inside wheel would *uncouple*.  

> Also consider what happens if you stall your vehicle downhill while
> engine braking, all in gear. Now do the same not in forward gear
> coupled, but in reverse gear, in a perverted way of trying to slow
> down more (sick to do in a manual, with a heavily slipping clutch,
> but we are experimenting, right?....one *can* do this pretty easily
> in an auto....a trashed auto on a Dutch military track several years
> back is the silent evidence of this abuse....8-))....anyway, after 
> stalling you start in gear again, reversing uphill....would the 
> coupling switch from outside to inside? Uphill it *must* the inside, 
> we don't dispute that. 

  Uphill, dowhill, sideways, upside down, it doesn't matter.  As far 
as I can tell judging by the physics of how these suckers actually do 
the uncoupling, the *fast* wheel uncouples when powering forward 
(making the axles move faster than they want to), and the *slow* 
wheel uncouples when the torque reverses (i.e. making the axle move 
*slower* than it wants to).

> But I can't see how it would switch from 
> outside to inside under such a huge load. Would be pretty scary.
> I know, very hypothetically, but still.

  This is a question that I just posed myself.  I'm hoping Mark 
Whatley will have a theory.  

> Note that I am not convinced that *my* theory is right, but none of 
> what I have seen thusfar is good enough to be included in the
> FAQ....and just saying that it does it so-and-so isn't enough in my 
> book....8-))

  Nor mine.  There is one more bit of knowledge that I need, and that 
is the *actual* *mechanism* of the uncoupling.  I know why it 
recouples (the springs between the center gears that force them into 
the side gears) but what's the deal with the uncoupling?   If it was 
just a matter of the ramped gear teeth pushing the gears apart under 
torque then it would be the *high* torque axle half that would 
uncouple, which we *all* agree can't be right.

 /---------------------------------------------------/
  Mike Graham, TLCA #5047             Ontario, Canada
  , 
  1981 BJ42 24V Diesel Land Cruiser "The Chew Toy"
  Find the ORDFAQ at 
  Diesel Technical LandCruiser list - 





To:               Offroad@off-road.com
Date sent:        Sun, 12 Oct 1997 21:45:37 -0700
From:             cruiser@akcache.com (Whatley,Mark)
Subject:          Coupled wheel on diffs
Send reply to:    Offroad@off-road.com

> 
>   An interesting question, which hopefully Mark Whatley will notice 
> and answer, is what happens if you engine brake into a turn, which 
> uncouples the inside wheel, then you stomp on the gas, or even just 
> apply easy throttle.

  With a Lock-Right, you will transition from having the inside
freewwheeling and the outside locked, to having the outside freewheeling
and the insode locked. This will happen very quickly, and normally
gently. It only takes about 6-8 degrees more rotation of the axle as
opposed to the ring gear to lock it when it is un,ocked (or vise-versa).

  The effect on the vehicle will be a slight lurch or twitch as it aslo
transitions from  tending toward oversteer, to tending toward
understeer. This action is what gives rise to the cautions about unusual
driveing characteristics of auto locker equipped rigs. It takes a day or
two to get used to, but it is not an extreme vehicle reaction. Just a
little unusual when first expereinced.
  The harder your engine brakeing, and the harder your subsequent
acceleration, the more noticable the twitch.

  On low traction surfaces, there is enough tire slip involved, that you
really can't tell when or if this transition takes place.

 In many low to moderate traction turns, the tires simple stay locked
and there is no difference in tire speed. This normally only happens in
situations where the traction is too low for the fact that the rear is
locked to be readily noticable in the vehicle handling.  


Mark...
-- 
TLCA #6303. Palmer Alaska. Tech Editor, Toyota Trails. ASE certified.
Self Proclaimed First Knight of the Iron Pig
(currently) 2 '78 FJ55s, '78 FJ40, '66 FJ40 and about 20 "parts rigs"
If it's not a Cruiser, it's just a jeep... Don't even say "SUV"...





To:               Offroad@off-road.com
From:             "Karl Olsen" 
Organization:     University of Utah
Date sent:        Tue, 14 Oct 1997 08:39:09 +0000
Subject:          Re: Coupled wheel on diffs
Send reply to:    Offroad@off-road.com

> In many low to moderate traction turns, the tires simple stay locked
>and there is no difference in tire speed.

So what about a long, gradual curve at highway speed ?  Would the 
locker unlock, or remain locked (scrubbing the outside tire all the 
way) ?  I have noticed that the lock-to-unlock shift (or vice versa) 
is very noticeable on very twisty canyon roads, but hardly noticeable 
if the road has a gradual curve.

I guess what I'm getting at is:  is the increased tire wear that is 
caused by an automatic locker mainly caused by highway driving (where 
the locker doesn't unlock), or mainly caused by "chirping" the tires 
when driving in town ?

-Karl
mailto:olsenk@probono.law.utah.edu





To:               Offroad@off-road.com
From:             mike@headwaters.com
Date sent:        Tue, 14 Oct 1997 21:48:00 +0000
Subject:          Re: Coupled wheel on diffs
Send reply to:    Offroad@off-road.com

Karl Olsen on Re: Coupled wheel on diffs:

> So what about a long, gradual curve at highway speed ?  Would the 
> locker unlock, or remain locked (scrubbing the outside tire all the 
> way) ?  I have noticed that the lock-to-unlock shift (or vice versa) 
> is very noticeable on very twisty canyon roads, but hardly noticeable 
> if the road has a gradual curve.

  You might get 100 feet in a very gradual curve before you build up 
enough 'bind' between the right and left tires to overcome the bias 
springs, but the springs will compress before your tires suffer 
*unless* you're really juicing it.  If you've got your foot down then 
the locker can't unlock.

> caused by an automatic locker mainly caused by highway driving (where 
> the locker doesn't unlock), or mainly caused by "chirping" the tires 
> when driving in town ?

  Chirping.  Using the foot during turns will keep the locker from 
functioning properly. 

 /---------------------------------------------------/
  Mike Graham, TLCA #5047             Ontario, Canada
  , 
  1981 BJ42 24V Diesel Land Cruiser "The Chew Toy"
  Find the ORDFAQ at 
  Diesel Technical LandCruiser list - 





To:               Offroad@off-road.com
From:             "Willem-Jan Markerink" 
Date sent:        Sun, 12 Oct 1997 19:24:59 +0000
Subject:          Lockers & engine braking
Send reply to:    Offroad@off-road.com

Another analysis regarding my theory of 'inside wheel always coupled
untill sufficient slip occurs', regardless of uphill, downhill,
forward or reverse:

*Suppose*....
....that the outside wheel would be coupled in case of engine braking
downhill, hence the inside wheel freewheeling with _less_ rpm than
the ring gear....now imagine sudden slip on that outside wheel....the
inside wheel would start to rotate faster and faster....while the
engine/diff/coupled wheel rpm would remain constant all the
time....until the inside wheel catches up with the rpm of the ring
gear (remember, it rotated slower than the ring gear when we
started)....and finally locks up like in an accellerating spin.

Mmm....I started this one as a falsification....I now am pretty sure
I just have proven the opposite....8-))

Please shoot holes in it, or this will be the final text to be added 
to the TAD FAQ....:-))

Willem (never afraid of admitting defeat in the name of 4x4 science) 
Jan

-- 
Bye,

Willem-Jan Markerink

      The desire to understand 
is sometimes far less intelligent than
     the inability to understand


[note: 'a-one' & 'en-el'!]





To:               Offroad@off-road.com
From:             mike@headwaters.com
Date sent:        Mon, 13 Oct 1997 06:01:57 +0000
Subject:          Re: Lockers & engine braking
Send reply to:    Offroad@off-road.com

Willem-Jan Markerink on Lockers & engine braking:

> *Suppose*....
> ....that the outside wheel would be coupled in case of engine braking
> downhill, 

  On a curve...

  Uphill, downhill, whatever, as long as the torque is reversed (i.e. 
engine braking is actually happening).

>hence the inside wheel freewheeling with _less_ rpm than
> the ring gear....now imagine sudden slip on that outside wheel....

If the outside (driven) wheel slips then the inside wheel could catch
up, yes, as long as the slide was significant (the inside wheel is
turning at road speed, it can't 'spin') and once it did catch up the
axle would relock and we'd be back to square one until there was a
torque imbalance again (a curve again).

>the inside wheel would start to rotate faster and faster....

  relative to the outside wheel, yes.

>while the engine/diff/coupled wheel rpm would remain constant 
>all the time....

  The outside wheel might well slow down due to the difference in 
dynamic vs. static friction.

>until the inside wheel catches up with the rpm of the ring
> gear (remember, it rotated slower than the ring gear when we
> started)....and finally locks up like in an accellerating spin.

  Yes, it locks, then we're back where we started.

> Mmm....I started this one as a falsification....I now am pretty sure
> I just have proven the opposite....8-))

  That used to happen to me in 3rd year Philosophy.  Rationality and 
Decision theory. The prof was a cool guy.  Drove an FJ55.  

 /---------------------------------------------------/
  Mike Graham, TLCA #5047             Ontario, Canada
  , 
  1981 BJ42 24V Diesel Land Cruiser "The Chew Toy"
  Find the ORDFAQ at 
  Diesel Technical LandCruiser list - 





To:               Offroad@off-road.com
From:             mike@headwaters.com
Date sent:        Tue, 14 Oct 1997 21:47:59 +0000
Subject:          Re: Re[2]: Coupled wheel on diffs
Send reply to:    Offroad@off-road.com

SandJC on Re[2]: Coupled wheel on diffs:

>      I was, of course, only talking about engine braking, but I see your 
>      point...it DOES seem that it would be the inside wheel uncoupling in 
>      this case, but that's not what (I believe) happens...I'm going to have 
>      to consult the locker diagrams again...

  Get yourself some popcorn, Joe, this is going to take a while.  I 
just had a mental breakthrough on this issue (thanks to info from 
Mark Whatley) so I'm ready to say that I've got it figured out.

Now the question is: which axle uncouples?   Rhetorical question: I'm 
going to explain it now.

 Glossary (in case you use different names for the parts):
 Using the Lockright as the model for discussion:

-  the CARRIER is the assembly that contains the locker
-  Axles are driven by SIDE GEARS (factory calls them 'couplers')
-  side gears mesh with CENTER GEARS  (factory term: 'drivers')
-  center gears are held apart by BIAS SPRINGS to initiate recoupling
-  center gears are kept from compressing the bias springs by STOP 
   PINS which can slip into holes when center gears rotate relative 
   to one another.
-  through an ELLIPTIC HOLE formed out of round grooves in both 
  center gears runs the PINION SHAFT which is connected to the
  diff carrier and actually drives the locker.

 Salient points:

-   The arrangement of stop pins and holes are engineered so that the 
center gears can only compress together slightly; just enough for 
only one axle to uncouple.

-  When the pinion shaft is bearing on the elliptical hole in the 
center gear pair it forces the center gears apart.  This happens any 
time there is torque transferred to the wheels.  

We agree that there has to be a difference in torque between the two
axles for the two driver halves (center gears) to turn relative to one
another so the pins can slip into their respective holes and the
center gears can compress together to uncouple an axle, yes?

We agree that this happens when one wheel is turning faster than the
other, no matter whether you're accelerating or engine braking?


Here's the scenario: 

We are engine braking.  The pinion shaft is pushing hard on the
trailing edge of the 'elliptic' hole through the center gears.  It's
pushing on the trailing edge because the wheels are pushing on the
driveshaft, not vice versa.   We start a turn to the right.  The
right hand tire starts to turn slower, which means the right half of
the center gear pair turns backwards (relative to the left half) so
that the pinion shaft is now roughly in the center of the trough on
the right-hand center gear, but still hard on the trailing edge of
the trough on the left-hand center gear.  Now the stop pins *can* fit
into their holes (once there's force to overcome the bias springs)
and it's possible for the center gears to get closer to one another
so an axle can uncouple.  At this point, the pinion shaft is still
hard on the trailing end of the left hand center gear's half of the
elliptical hole, but slack on the right hand center gear. This means
that it is pushing OUT on the left hand center gear, but *not*
pushing on the right hand center gear.  Since the left hand center
gear *can't* push in, it stays coupled.  As soon as the torque built
up in the right hand center gear is enough to push away from the
right hand side gear using the ramped sides of the teeth, and
overcome the force of the bias springs, the pins will slip into
their holes and the right side will uncouple.  It *has* to.  The
left side center gear is still being held out by the pinion shaft, so
the right side center gear must uncouple. The right side is the slow
tire; the inside tire.

Now what happens when you add some throttle while still in the turn?
The torque changes direction.  Both the left and right halves of the 
center gear rotate backwards (relative to the carrier).  They must 
rotate together because they are still held by the pins between them. 
 As they rotate backwards the pinion shaft is no longer pushing on 
the trailing edge of the elliptical hole on the left side center 
gear.  It can now move inwards (if it wants).  The center gears 
continue to rotate backwards (relative to the carrier) until  the 
pinion shaft hits the *leading edge* of the elliptical hole on the 
right hand center gear (remember it's rotated slightly backwards of 
the left hand center gear).  Now the right hand gear is forced 
outwards by the pressure on the leading edge of the elliptical hole. 
As soon as the teeth match the right center gear is forced out and 
the right hand axle (inside) couples.  Now, since there is torque on 
the outside tire (it is currently driven, right?) yet there is no 
force on the leading or trailing edge of the left center gear to 
force it outwards, it happily disengages (due to the ramped teeth and 
the fact that the center gears are already compressed together) so 
that the transfer of power is quite smooth, but still perceptible due 
to understeer/oversteer. 


  Yes, folks, this just has to be it.  Willem-Jan, you can put that 
in your TADFAQ. 


>      If you think about it, the operation you are describing could be 
>      disastrous...for example, when you are on that freeway on-ramp 
>      decelerating with the outside wheel doing all the braking...the FASTER 
>      wheel.  Now you put your foot into it to accelerate onto the 
>      freeway...all the power now switches to the INSIDE wheel, the one 
>      that's going slower!  All the momentum of the engine and drivetrain 
>      must come to a crashing deceleration as the rpm drop...while you are 
>      trying to accelerate.

  There is no 'crashing drop'.   You are going through a torque 
transition period from reverse to positive.  Somewhere in there is 
the right amount to keep things smoothish.

>      My brain hurts...where's my coffee?

  How does your brain feel now?  8-)

 /---------------------------------------------------/
  Mike Graham, TLCA #5047             Ontario, Canada
  , 
  1981 BJ42 24V Diesel Land Cruiser "The Chew Toy"
  Find the ORDFAQ at 
  Diesel Technical LandCruiser list - 





To:               Offroad@off-road.com
Date sent:        Wed, 15 Oct 97 11:21:29 EST
From:             "SandJC" 
Subject:          Re[2]: Lockers- gear slippage
Send reply to:    Offroad@off-road.com

wasserman on Lockers- gear slippage:

> Nope- take out a lockright and try it. It's always the side with the 
> longer travel that makes the gears slip- by slipping I mean let the
> rounded sound of the gears pass one another to make that clicking sound.

  Read my post on this issue.  It is physically impossible for the 
outside wheel to uncouple during engine braking.


     Aaack, ouch...squish plop!  (that's the sound of my brain falling out 
     of my ear...

     I'm much better now.

     I haven't read Mikes whole message on this subject (not enough time or 
     popcorn), but after some introspection I can't think of any other way 
     it could work...of course I can't think of my home phone number right 
     now either...

     You must be right Mike, I can't think of amy way the outside wheel 
     could uncouple while decelerating...problem is this is not what I've 
     been told, and what I THOUGHT I have seen in other's trucks.

     Somebody with a locker try this:  Drive in the tightest circle you can 
     manage, so the two wheels will be turning at measurably different 
     speeds.  With your foot on the gas note the engine RPM.  Now take your 
     foot off the gas and see what happens.  In the above scenario the 
     engine rpm should go UP to match the speed of the inside wheel.  Now 
     put your foot back into it, and I would expect the rpm to drop again 
     to the accompaniment of a typical locker bang.

     Report back to the list with your results.

     If this is true, then I finally understand why lockers pop and bang in 
     parking lots!  If the rpm stays the same, then it's back to the 
     drawing board since I can't imagine how one would design a locker that 
     performs as I originally believed.

     Joe Sand
     Knowledge is power, however ignorance is bliss...





To:               Offroad@off-road.com
Date sent:        Thu, 16 Oct 1997 15:51:37 -0700
From:             Don Alderrou 
Subject:          Lockers- gear slippage
Send reply to:    Offroad@off-road.com

Joe,

   I can't do your experiment b/c the LockRight is behind an auto tranny.

   However, I did something similar accidently without knowing it and not
   understanding what happened until some time later.  This event confirms
   the slow wheel (inside wheel in turn) un-locking during engine braking.

   Let me describe ...

   Off-roading in the snow last year.  Jeep sitting with one rear wheel 
   in a puddle of water/mud/ice/muck for 15 minutes waiting for jeep in
   front to clear an obstacle.  About a mile later, going down hill while
   engine braking.  Need to slow down more so lightly press on brakes.
   (The auto tranny does not engine brake enough sometimes at low RPM.)
   The rear wheel which was in the muck locks-up without effecting the
   other three wheels.  Since on the snow, no friction between the 
   locked-up tire and the ground/snow/ice.  What happens?

   The other three wheels (open front diff) keep turning with the 
   engine braking.  The LockRight is "click click click" like mad since
   one wheel is not turning while the other one is turning.  This is the
   extreme case of the engine braking turn where the slow (inside) wheel
   unlocks, except I was going straight.

   Whew!  Now time for some popcorn. :-)
--Don

--------------------------------------------------------------------
  Don Alderrou.  S.F. Bay Area, Ca.            mailto:dona@seeq.com
  Gettin' Off 4WDC  http://www.studio-west.com/gettin-off/dir.shtml
  97 TJ Sport. 5sp, D44, 4" lift, 33's, 4.10's, ARB's, winch.
  92 XJ. Auto, 4" lift, 31's.

  Get A CA4WDC Calendar & Chance to Win 5 Tires from BF Goodrich:
  http://www.studio-west.com/gettin-off/calendar/ca4wdcal.html





From:             sij@skyrr.is
To:               80_series@palladium.corp.sgi.com
Date sent:        Fri, 8 May 1998 15:11:55 +0000
Subject:          Re: [80] 35" tires
Send reply to:    80_series@palladium.corp.sgi.com


While the Detroit Lockers are sturdy pieces of equipment, easy to get used
to on the road, and very easy to love off road, I can still remember a few
missed heartbeats while cruising at 110kmh on the cruise control while
going through gentle curves, the cruise contol alternately accelerating and
decelerating to maintain speed. This would cause marked changes in
direction as the locker alternately produced understeer on acceleration and
oversteer on deceleration. Particularly memorable are such events going
uphill when the auto kicked down as well. At those moments a little switch
in the dash would have been welcome.

Regards,
Siggi






From:             "Willem-Jan Markerink" 
To:               dtlc@helios.net
Date sent:        Mon, 6 Mar 2000 16:33:44 +0100
Subject:          Re: [DTLC] Used Aussie FF-axles & cable lockers
Send reply to:    dtlc@helios.net

On  5 Mar 00 at 21:36, Susan and/or David Dannenberg wrote:

> Well, ya' got me sold. Any dissenters in the audience?

Yes, me.
On dry roads, you also effectively get a higher gear ratio in corners, since
it's the inside wheel driving (propelling the vehicle over the inside-radius, ie
relatively high speed, high gearing....had it be driving the outside wheel, it
would effectively be a lower gearing (luckily this is what happens when
engine-breaking)). While this is not a real problem on flat ground, this ain't
good on steep hairpin corners....might force you to shift one gear lower.

Yes, I know, a manual locker can't be locked at all in such hairpin 
corner (dry pavement).
But, also: suppose traction gets a bit worse (rain, spinning inside wheel 
in such corners normally), and you would want to engage 4wd....in 
that case the above radius problem gets only worse....instead of a 
front axle (average of relatively large front wheel radii) fighting a 
rear axle (average of relatively small rear wheel radii), you get a 
front axle fighting the inside wheel (with an evern smaller radius).
Hence binding gets worse, and the tendency to spin that inside wheel 
(and lock solid) is larger.

Mechanically an auto-locker is more friendly for the rear half-shafts 
than a manual locker, especially when rockcrawling. But that does not 
necessarily hold true for the rest of the drivetrain, or in other 
scenario's....instead of spreading torque over two halfshafts in a 
corner, torque is now sent to only one halfshaft.

(things become again a bit different if you have a front auto-locker 
as well....in that case it's the front inside wheel fighting the rear 
inside wheel, a milder scenario....until any wheel spins, and locks 
up the wheel on the other side)

If there are any mathematics in the room, they might be able to 
calculate the gearing difference in tight corners.

Oh well, what we need is a Quaife geared LSD, in combination with a KAM 
locker....the best of both worlds. Possibly even with optional 
brake-assist on later models with ABS (which works much better on 
geared LSD's than on open diff's....much less energy wasted).

--                 
Bye,

Willem-Jan Markerink

      The desire to understand 
is sometimes far less intelligent than
     the inability to understand


[note: 'a-one' & 'en-el'!]





FROM: Roger Brown 
SUBJECT: Re: How much noise does a Lockrite make?
DATE: Thu, 09 Mar 2000 09:39:07 -0800
ORGANIZATION: SGI
NEWSGROUPS: alt.autos.toyota.trucks,rec.autos.4x4

Chris Phillipo wrote:
> Thanks for the info, I have a 93 v6 4 runner automatic which I plan to keep
> until I die or the seat falls through the floor pan.  So I think I'll wait and
> spend the extra money for the newer unit for the sake of sanity.  Ever driven
> with the Lockrite in snow?  I've driven limited slips with no problems, is the
> lockup more of a surprise than a LSD gives you?  I like to do a little impromptu
> rally driving on the back roads with a Mazda 4wd 323 GTX owning friend of mine
> on nights it snows when we are leaving work, I'm hoping this thing won't put me
> in the ditch.

Well, I run a rear Detroit/front TrueTrac on my 5-sp. 4Runner.  In 2WD, it
gets a bit dicey in the snow, rear end wants to twitch at the slightest
provocation.  When I pull in hte front axle, it settles down quite a bit. 
When starting out, if there is the slightest degree of crown on the road, the
rear end will tend to slip to the downhill side until the front wheels pull it
back straight.  Once you anticipate that it will happen, its not a big deal to
compensate for.  I think the LR has less "slop" in it than the Detroit, so it
may be a bit better. 

I'm planning to switch to ARBs front and rear.

-- 
    Roger Brown	
http://reality.sgi.com/rogerb/4x4/4R_TechInfo.html#Differentials

To:               LandCruisers@tlca.org
Send reply to:    LandCruisers@tlca.org
From:             "Willem-Jan Markerink" 
Date sent:        Tue, 10 Feb 1998 09:28:24 +0000
Subject:          Re: Lockers in the Front

On  9 Feb 98 at 16:42, Steve Irving wrote:

> After getting stuck, I am interested in getting more traction, but
> can't afford (or , more to the point, justify the expense of) ARB
> air lockers front and rear.  The "Lock-Rite" I think it is, is ch
> aper, and a sound piece of kit (comments as to the veracity of
> this assumption are appreciated).  I had the brainwave of putting
> one in the front axle as the most cost-effective and everyday
> practic l option.  The reasoning here is that (I think) as long as
> the hubs are unlocked, the locker would be disengaged, thus
> avoiding any steering weirdness on dry pavement. 

Correct.

> Is this correct, or am I out in left field?  Constructive comments
> or viable alternatives appreciated. 

The problem arises on packed snow and ice while on the road....you 
want 4wd in that situation, but not the auto-locked front axle. Even 
a rear auto-locker can be tricky in those conditions, not to mention 
a front one.
Other than that it is a nice solution, but I wouldn't want to
sacrifice onroad 4wd if the possibility of snow and ice is high at
your place. 

-- 
Bye,

Willem-Jan Markerink

      The desire to understand 
is sometimes far less intelligent than
     the inability to understand


[note: 'a-one' & 'en-el'!]




To:               LandCruisers@tlca.org
Send reply to:    LandCruisers@tlca.org
From:             "Willem-Jan Markerink" 
Date sent:        Tue, 10 Feb 1998 20:02:02 +0000
Subject:          Re: Lockers in the Front

On  9 Feb 98 at 14:22, Whatley,Mark wrote:

> 
>   When the hubs and front drivetrain are engaged while off road,
> there will be more adsverse steering effect than if the single
> locker was in the rear. While this is also the case with lockers
> in each end, it seems a bit worse (perception probably) when there
> is just one in the front. 

I think it can easily be proven that an auto-locker in the front-only is 
worse for steering than auto-lockers on both ends. 

Front-only: In a turn, the front inside wheel is driven at the same
rpm as the average of the rear wheels, which means that it wants 
'faster' than the rear end....hence a strong 'straightening' effect.

Both ends: the inside front wheel is now driven at the same rpm as 
the inside rear wheel....in this case the resulting speed difference 
is much less, as the radius of inside-front and inside-rear are less 
different than inside-front vs average-rear.


-- 
Bye,

Willem-Jan Markerink

      The desire to understand 
is sometimes far less intelligent than
     the inability to understand


[note: 'a-one' & 'en-el'!]





To:               LandCruisers@tlca.org
Send reply to:    LandCruisers@tlca.org
From:             "Willem-Jan Markerink" 
Date sent:        Sat, 21 Feb 1998 00:38:44 +0000
Subject:          Re: Locker in the front diff of a vehicle without power steerin

On 20 Feb 98 at 23:22, Colin Dowd wrote:

> 
> Does anybody have a locker in the front of their vehicle without power
> steering ?
> What type is it ? (ARB Air Locker, Detroit , Lock Right )
> 
> I have recently been to my local TJM store asking about a locker for the
> front of my BJ40 and the sales person told me that a Lock Right is so
> sensitive that it will unlock almost instantly and therefore will not affect
> my steering very much.
> Is this true or not ?

Ask him how it feels if only the inside tire pulls you through a 
corner. Since that is exactly how a Lockright/Detroit operates when 
it unlocks.

> I believe the ARB Air Locker has to be disengaged to turn corners is this
> true ?

If you want a steering radius of less than infinity, then yes....;-))
With an full locker like the ARB, the wheels are fighting each 
other....with an autolocker only one wheel will fight....but it will 
fight *you*....8-))

> Is the Detroit locker sensitive enough to unlock during steering ?

It unlocks allright, but boy you need PS to resist that 
torque-steer....:-))
I don't think it is any different than hitting a curb.... 

Look at the bright side: an auto-locker won't put much stress on the 
front drive train like a full locker does, it will only stress your arms....

-- 
Bye,

Willem-Jan Markerink

      The desire to understand 
is sometimes far less intelligent than
     the inability to understand


[note: 'a-one' & 'en-el'!]





To:               LandCruisers@tlca.org
Send reply to:    LandCruisers@tlca.org
Date sent:        Fri, 20 Feb 1998 20:07:31 -0500
From:             Gregg Jarvis 
Subject:          Locker in the front no P/s

Colin wrote:

> Does anybody have a locker in the front of their vehicle without power
> steering ?
> What type is it ? (ARB Air Locker, Detroit , Lock Right )
>
> I have recently been to my local TJM store asking about a locker for the
> front of my BJ40 and the sales person told me that a Lock Right is so
> sensitive that it will unlock almost instantly and therefore will not
> affect my steering very much.
> Is this true or not ?
> I believe the ARB Air Locker has to be disengaged to turn corners is
> this true ?
> Is the Detroit locker sensitive enough to unlock during steering ?
>
> Any information based on your experiences would be appreaciated
>
> Thanking You

Colin, Unfortunately for the low price you pay for the Power traxx they
are not complex nor sensitive. They do work well however.  I highly
recommend them in the rear for the incresed $$ savings and good
all-around performance. My buddy has them front and rear in a non P/S'd
40 and let me tell ya'  -several times in tight situations we both had
to drive(steer) -Yes, at the same time!! We mostly drive hubs unlocked
until we need 'em.And you will pull a couple of muscles when running the
fronts locked.

My .02 cents- I have yet to do the P/S conversions in my 40's so I opted
for the Auburn LSD and it is great. That unit will let you steer much
easier than the Lock-Rite. Yes it is more expensive and not as "true" as
a locker, but a guy gave it to me 'cause he wanted my open diff so i
swapped them and have not complained.If you have the $ go ARB or some
LSD and if not wait for the P/S and a Lock-rite should do. As for me, I
don't mind manual steering in th woods- with a locker it is a necessity.

Gregg Jarvis
Suffern, NY
82 fj40 lockrite -rear   Auburn-front
75 fj40 lockrite rear  V8- front





To:               LandCruisers@tlca.org
Send reply to:    LandCruisers@tlca.org
Date sent:        Sat, 21 Feb 1998 04:50:46 -0500
From:             "Breitbach, Gary" 
Subject:          Locker in the front diff of a vehicle without power steering ?

Colin,

>Is the Detroit locker sensitive enough to unlock during steering ?
>
>Any information based on your experiences would be appreaciated

Sorry, this is not my direct experience, but I was talking
quite a bit with a guy that built an off-road truck from the ground
up.  He  has Detroits front and back.  He says on steep down
hill runs he has to take it out of four wheel drive.  He  says he
cannot steer the truck otherwise.

Gary Breitbach
TLCA #6227
'76 FJ40 w/ little untouched
Portland, Oregon





To:               Offroad@offroadlist.com
From:             "Shaw, Steve" 
Subject:          Detroit Lockers in the front (was Several (lockers))
Date sent:        Sun, 6 Dec 1998 20:58:41 -0500 
Send reply to:    Offroad@offroadlist.com


>>>Your right I forgot about that, I get confused because lock rights are
>>>better up front, Because they are easier to open.
>>
>>The Detroit Locker (original locker) is very easy to unlock.  My front
Dana
>>60 Detroit opens very easily (as does the rear).  If I have the front
tires
>>off the ground (working on the truck) and spin one tire by hand quickly it
>>unlocks with an insignificant amount of torque and the other tire doesn't
>>even spin.  The Lock-rights I've seen require more torque to unlock.

>Excuse me, but I am only going by the manufacturer and numerous people that
>complained after putting them in the front end, and the manufacturers
>responce to them. Detroit lockers are NOT intended for front end use.

I don't want to get involved in a flaming war, but you are incorrect.  I
have researched lockers to the nth degree.  Tractech is only cautious in
recommending auto lockers (both the EZ-locker and Detroit locker) for the
front because of the 4wd steering effects (that we all know about).  For the
average Joe, driving primarily on the street I wouldn't recommend one for
the front either.

I have all of their documentation and they, at worst, state that you should
call Tractech for advice.  In fact on their web site
(http://www.tractech.com/tractech.htm 
) they state:

"Locker" In Front Axle? Yes, if front drive can be disconnected - either
from inside or outside the vehicle - while driving on hard surface roads."

In their technical service bulletins (from the engineering department) they
describe the steering effects and compromises running auto lockers in the
front.  These effects are virtually identical for the Detroit Locker, the
EZ-locker, the new Gearless Locker, and all Powertrax auto lockers.  The
amount of torque required to release any of these is insignificant to the
truck.  

The steering problem with all of these is due to the different turning
radius for the tires (when enough traction is present).  This causes the
front locker to go into reverse mode, allowing the front inside tire and the
rear outside to potentially free wheel, but forces the outside front and
inside rear to turn the same speed.  This causes the steering to strongly
pull to center (but not as bad as a true spool).  Also, if the corner you
are trying to take is sharp enough to make both front tires have a larger
turning radius than both of the rear then all 4 tires are forced to turn the
same speed (the lockers lock up), making steering even more difficult (just
like true spools).

Steve Shaw

To:               Offroad@offroadlist.com
From:             robert hazel 
Subject:          Detroit Soft Lockers - any good?
Date sent:        Sun, 19 Apr 1998 08:34:03 -0400
Send reply to:    Offroad@offroadlist.com

>Has anyone tried the new Detroit Soft Locker?  How much quieter, smoother,
>nicer are they compared to the original Detroit Locker?  Is the Soft Locker
>as strong?  BTW: I will be installing it in a Dana 60 axle, I'm changing
>from 4.88's to 4.11s.

I have around 100k miles on the one in the 60 under my Bronco. The 'soft'
locker eliminates alot of that abrupt 'bang' felt with the standard Detroit.
To hear mine ratchet in a turn, I really have to 'try' to hear it. Zero
complaints here.

Bob  

To:               LandCruisers@tlca.org
Send reply to:    LandCruisers@tlca.org
From:             "paul decker" 
Subject:          Water Wetter  and Lock-Right grabbing
Date sent:        Sun, 22 Feb 1998 01:15:10 -0800

Check out the Red Line Oil home page at 
http://www.redlineoil.com/index.htm  Red Line is the premier oil of auto
racing.  Their Water Wetter really works as does their oil and other
products.  

When I bought my 78 FJ40 with a Lock-Right it would lock up and ratchet
when making tight turns on pavement.  It would also grab at times when
driving at speed and lurch to one side.  I was about ready to take the
Lock-Right out.  I called Red Line and they recommended that I change the
rear differential oil to the  manufacture's reccomended weight of Red Line
and add their "LIMITED-SLIP DIFFERENTIAL FRICTION MODIFIER" in 4 oz.
increments until the desired effect was achieved.  With Red Line  and 4 oz.
of the Friction Modifier it is a completely different Cruiser.

Paul Decker  ascpaul@worldnet.att.net  TLCA 6649





About wear characteristics with the Detroit EZ-locker:


From:             "Clarissa & Simon" 
To:               
Subject:          [DTLC] RE:worn out EZ locker
Date sent:        Wed, 5 Apr 2000 00:55:04 -0500
Send reply to:    dtlc@helios.net

Hi All,
l just removed an E-Z locker out from my friend's BJ42  and installed ARB
front and rear on the 42.
The EZ locker was banging and clanking when we were playing on the
snow,feels like it was slipping.
The locker looks ok,so l install it in the rear diff of my BJ60,it was
clanking and banging during cornering and under load.
A phone call to Detroit locker warranty office and the lady said 4 years is
about all l can get from it.(locker is 4 yrs old).She said the corners of the
teeth are rounded off,it is very hard to tell if they are rounded. Does anybody
has a lockrite or EZ locker that is worn out?????????? l am going to buy a
locker for the rear of my BJ60(daily driver) in the near future,l am hesitant to
buy the lockrite. Does the "O rings" on the ARB wears out often,l have heard
stories they wear out in 25k miles. simon

 

With respect to the GM TAD, Taylor asks:  
 
> Am I missing something?  This GM type of lsd sounds like a big crock.  It 
> must have some good point other than no clutch to wear out. 
 
Well, I have tried this before, but I will try it again.  This  
explination is going to be long, so if you don't care to know about the  
GM LSD, skip this post.  Otherwise read on.  Simple explanation:  The GM  
"LSD" is really more of a locker.  There are no  clutch loading springs  
inside, but there are clutches, just like a clutch LSD.  There is also a  
little "governor" type defice that senses relative wheel speed.  When the  
relative speed exceeds approx. 100 rpm, the governor catches on a latch  
and stops motion of a "ramp" gear relative to the case.  The ramp gear  
spreads apart because half of it is secured to the case and half is  
secured to an axle shaft which is spinning relative to the case.  This is  
what loads the clutches.  Actually, the tolerences involved when new will  
allow no relateve speed difference between wheels in a locked condition.   
Hence, if you put one tire in the air and one on cement, then go, the one  
in the air initially spins, then the thing goes klunk and suddenly both  
wheels spin at the same speed.  The tire on cement will smoke if you keep  
at it.  I have put one tire on ice and one on cement and left a black  
streak on the cement. 
 
Since there are clutches, the thing will be slightly better than an open  
diff when exposed to a load.  This is because the spider gears exert some  
side forces on the side gears, and this loads the clutches too.  Note  
that the clutches are all steel disks and I am almost positive that  
_NO_ additive is required for this diff to function.   
 
With respect to ice and snow, _any_ lsd or locker is bad on road.   
Contrary to popular belief, lsd's don't "sense wheel slip and transfer  
torque accordingly".  They sence torque and as torque increases, so does  
the biasing power of the diff.  They do have some initial biasing power  
due to the clutch preload springs.  With respect to this situation, yes,  
the GM lsd is a little worse in that all of a sudden you loose traction.   
Icy roads are not what it really helps with.  Were it does work is when  
you are on trails or other situations where one tire looses traction.  In  
this case, the GM lsd will lock and move you.   
 
The locking procedure is a little rough on parts if you are hard into the  
gas with a big load.  Of course even in no-load situations the thing puts  
some shock into the system, but not enough to cause any damage in a stock  
application.  Now, if you put 35's on and sink it in a huge mud hole and  
think that your locker should catch and pull you free in an attempt to  
rock it out, you have anyther thing coming.  There is a built in shear  
device that will render it an open diff if a certain torque load is  
reached.  This is to prevent you from breaking either axle, which was only  
designed to handle slightly more than half the max. torque from the  
engine.   

 


FROM: Gordon Vorenkamp 
SUBJECT: Re: Locking Differential
DATE: Sun, 31 May 1998 07:38:28 -0700
ORGANIZATION: Cutting Edge Communications, Inc. - http://www.cet.com/
NEWSGROUPS: rec.autos.4x4

Ed Hale wrote:


> rgrandmaison@comdt.uscg.mil wrote:
>
> > In article <6kjtdf$c0r$1@supernews.com>,
> >   "In the Hollow (remove  for email)"  wrote:
> > >
> > > the locking diff is probably the only thing which WOULDN'T cause a slippage!
> > > It is a locker between the drive wheels, so only if you were on something
> > > slippery would you feel it. My locking diff (1992 K2500) feels that way when
> > > one wheel is on ice, wet leaves, etc and the other is on terra firma. Hope
> > > this helps!
> > >
> > >
> > The slippage I feel is in the drive train.  It's very brief (less than a
> > second), and this may be normal when taking off from a stop.  I was just
> > curious if anyone else had experienced this.
> >
> > -----== Posted via Deja News, The Leader in Internet Discussion ==-----
> > http://www.dejanews.com/   Now offering spam-free web-based newsreading
>
> I have a '98 Suburban and mine does the same thing occasionally.  If you will have
> the diff fluid changed (a required maintenance item anyway) it will stop for a
> while.  Mine didn't slip at all for the first few thousand miles and then started
> about 5,000.  I now have 23,000 on it and it has almost stopped, but I have
> changed the diff fluid three times along the way.  This change is cheap so why
> not.
>
> Ed
>

HI:

Your slippage may just be backlash.  My interpretation of backlash is slop in your
drivetrain.  This "backlash" is usually more spefically defined as free rotation of
the gears in your differential before the axle is driven.  My lockrite automatic
locker added 20 degrees of backlash to the drivetrain in my aready sloppy 1991 chevy
1/2 ton work truck with manual transmission.  A vehicle with an automatic transmission
will probably have the torque converter taking up alot of the slop most of the time
but the automatic will sometimes completely disengage the power to the drivetrain at
idle rpm and then you may get to feel the slop in your drive train.
Gordon

 
 
To:               Offroad@offroadlist.com
From:             "Shaw, Steve" 
Subject:          Lock-Right No Slip
Date sent:        Fri, 10 Jul 1998 13:29:34 -0400
Send reply to:    Offroad@offroadlist.com

I called up Powertrax and requested technical info on the No Slip.  They
sent me a package that shows a number of cut away and cross section views.
I then called them back to clarify how they work and spoke to their
engineering manager (don't have his name with me).  This is my
understanding:

- Basically it uses the same dog clutches that the Lock-Right uses; the
difference is in how they are applied.
- The key functional difference is they use a "synchronization ring" to
effectively delay the locking up and switching engagement from side to side
(when you switch from accelerate to coast and visa versa).  It requires a
differential rotation of around 1/3 of a turn before it switches once it is
unlocked.
- They also use a secondary clutch system to produce drag between sides when
it is unlocked (similar to a LSD).

What this gives you is:
- When you switch gears while driving around a corner on pavement you don't
get the lurching oversteer/understeer typically seen with lockers - unless
you're very slow at switching gears (the driven wheel will switch
eventually).
- With the secondary drag clutch the switches from side to side are much
less noticeable when they do occur.
- They claim that because the unit will be switching side to side less often
and the secondary clutches will smooth out the transitions that the unit
will be much more durable than the current Lock-Right.

Unfortunately it isn't available yet, but they told me some units will be
available very soon (by now - I called them 2 months ago).

Steve Shaw
Carp, Ontario
Canada
1976/77/84/91 K20; now with a Dana 60 front with a Trak-loc, 14 bolt FF rear
with a Detroit, 4.88 gears, and BFG 35x12.5x16.5 MT's (brake in & testing
starts this weekend!!!)

Date sent:        Sun, 31 Jan 1999 23:34:02 -0800
From:             Mark Whatley 
To:               landcruisers@tlca.org
Subject:          Re: 
Send reply to:    landcruisers@tlca.org

Dana Adams wrote:
> 
> Hi all.
> 
> With all the discussion recently about Lockers on Ice, I thought I'd ask
> the wisdom of the list what would happen if you had a blowout on the
> highway, at say, 70 mph?  Assume the locker is a Detroit.
> 
> I know a blowout at that speed is no picnic, even with an open diff, but
> it seems to me that with a Detroit locker, the situation would be even
> worse.

  The blown tire would have a smaller circumference than the inflated
one. So it would be rotating faster from contact with the road as long
as you were still moving. This would initially unlock the blown side
from the diff. If you slowed with brakes, it would remain unlocked. If
you instead used the engine to slow the vehicle, then the situation
would reverse, and the blown tire would be the one which would lock, and
provide the force to brake the rig, and the inflated tire would free
wheel.

  Result in terms of controlling the vehicle...   ????


Mark...
-- 
Mark Whatley, ASE. "Function over Form." Iron Pigs Forever.
Owner, Cruisers Only, Palmer Alaska Mailto:cruiser@mtaonline.net
Chrome and leather don't get you down the trail. Don't even say "SUV"
http://www.tlca.org Tech Ed Toyota Trails Mailto:techexchange@tlca.org
82 FJ60, 78 FJ55 78 FJ40, 66 FJ40, 63 FJ45. Lotsa parts rigs.

From:	Shaw, Steve 
Sent:	Friday, February 05, 1999 2:21 PM
To:	Offroad (E-mail)
Subject:	Detroit Lockers in front Axles

I just finished catching up with the list and noticed another post stating
that a Lockright unlocks easier than a Detroit and is therefore better for a
front axle application.  Here's some info that I discovered using a Detroit
in my front Dana 60.

-	Tractech has completely stopped making the "old style" locker for
Dana 60's (and most other's).  They now only produce the "Soft-locker" for
almost all axles.
-	The Soft-locker has a set of internal "clutches" that act between
the diff case and the side gears (a bit like a standard LSD).  These
clutches increase the torque required to release one wheel and continue to
drag when released.  This makes the units quieter and smoother, but the
additional torque bias is undesirable for the front.
-	Being a Mechanical Engineer and wanting the best setup I called up
Tractech and spoke with their engineering department about this issue.  They
said since the majority of their sales are either strictly off-road or rear
axle applications they hadn't fully investigated this issue for front
applications.
-	They had a number of internal meetings and discussions and came to
the conclusion that for the best performance in a front axle the thrust
blocks and center bellville washers should be removed prior to installing
the unit.  They told me that they were generating a tech note on the issue
to recommend this, but weren't planning any testing.  They also assured me
there would be no loss of warranty and that the unit should actually last
longer with the mod.
-	I made the mod and it works perfectly.  The most significant
improvement is when running hubs locked in 2wd.  At highway speeds (worst
case) I can hardly detect the locker.  With the stock soft-locker there is a
stronger pull to center and sloppier steering (although it's not that bad
either with a heavy full size truck).

Now if I jack up the front of the truck and spin 1 wheel with the hubs
locked, transfer case in 2wd the locker unlocks and only 1 wheel spins.

I suspect that with the soft-locker clutches removed it unlocks just as
easily as a Lockright (no one in our club is running one in a Dana 60 so I
can't check this).

If anyone wants to check into this or consider doing it, I'd suggest you
call Jim in the engineering department at Tractech (810) 759-3850 (there are
two Jim's in engineering & I forget which one I spoke to - both should know
about the tweak).  I 
don't know if they've produced the tech note or done any testing since I
installed my Detroit (summer 1998).

So far I've put about 10,000 severe kms (including serious off-roading,
10,000 lb trailer towing, driving through 3' deep snow with 4 tire chains
and plowing snow all winter) on the truck since the axle mods, probably
about 2500 kms with the hubs locked and everything is working perfectly.

Steve Shaw
1976/84 K20/30, 4.88 gears, Detroits at both ends, 4" Rancho, RS9000's, 35"
BFG MT's & minor fender trimming
http://www.off-road.com/~ovo/members/sshaw/sshaw.htm

Summary Pro's & Con's

Summary Pro's & Con's

Summary Pro's & Con's

An example:
Suppose you have a torque of 7000Nm available on the carrier of a TorSen diff. With only 1000Nm grip available on one wheel, the diff biases 6000Nm to the other wheel (1:6; for ease of reasoning assuming that this other wheel has enough grip to 'accept' this amount of torque without slip). With an open diff in the same sitation you would have only 2000Nm grip (1000Nm on each wheel), with a TorSen 7000Nm (1000Nm on one, 6000Nm on the other wheel).

For a better understanding, I always try to imagine it as allowing speed differences between axles caused only by torque coming *from* the outside, not going to the outside. It is then multiplied and send to the other axle.

The Quaife mostly resembles a TrueTrac/Powr-Trac, but adds another element, friction, by which it also functions when one wheel is airborn. It functions like a lower limit of torque transfer.

Summary Pro's & Con's

They are claimed to have a narrow area of handling at the grip limit. Normally, you can rely on an inside wheel-spin only, still having the outside wheel for lateral grip. The chance that both wheels start to spin at the same time is larger, but the chance of slip occurring in general is lower of course lower, due to increased total traction.

With one wheel airborn, slip-torque = 0, so even a muliplication by 3 or 6 will equal a grip-torque of 0. You are stuck.
However, by applying the brakes you can simulate a slip-torque larger than 0, thereby sending a multiplied torque to the grip wheel, which in turn is larger than the brake torque on that side. You probably can free yourself. (AFAIK, this procedure is also stated in the Hummers manual, and mentioned several times in articles about other TorSen-equipped trucks)

A Quaife diff basically adds a lower limit of torque transfer to the TrueTrac principle. But although this friction is multiplied by its gears and also works with one wheel airborn, you still can get stuck, like you could with a friction TAD, only later. The brake-assist procedure is similar.
It also wears out, but if it ever does completely, you would still have an ordinary TrueTrac.

Earlier TrueTracs had 2 sets of worm gears, and the manufacturer recommended not to use tires over 32". More recent versions have 3 sets of worm gears.
Kevin Alcox posted his experience with the first generation model:

 
 
>>Anyone have any experience with the Detroit True Track Locker in the Front  
>>Differential? Is it hard to steer, ETC? 
>> 
>>                                        Thanks, Terry Koch 
 
First of all, it is not a true locker. It is a gear driven limited slip 
unit. I have ran one for about 2 years before it broke. My impression was 
that it worked better with smaller tires. I noticed a difference in  
operation between 32" and 33" tires. 
 
I ran it in a Dana 30 in a CJ7 that I daily drive and it worked fine. The 
steering was not adversely affected, although it did return to center sooner 
and with more force than an open diff. 
 
On the trail with 1 front wheel in the air, application of the brake would 
cause the tire on the ground to spin, but I broke a couple of axle u-joints 
doing this. The True Trac finally gave out last month when it stripped the 
teeth off of the gears inside it. I have sent it off to Dyneer, who said 
that they were going to warranty it because they have had this problem with 
this early design, which they have since corrected. 
 
If you are have smaller diameter tires or do a lot of highway driving in  
4WD, then it works great, but if you have big tires and/or do a lot of 1 
wheel in the air 'wheeling, then I would look at something else. 
 
======================================================== 
Kevin Alcox  '80 CJ-7  kalcox@animas.tcinc.com 
Littleton, CO     Mile Hi Jeep Club - Patrol 16 Leader 
======================================================== 
 

Some brands have two sets of clutches (Powerlock), others have a cone shaped clutch instead of a flat surface.

The below explanations were posted to the ORML:

To:               Offroad@off-road.com
From:             Willem-Jan Markerink 
Date sent:        Thu, 10 Apr 1997 13:51:15 +0000
Subject:          Re: Ford Trac Loc help and need 4x4 with interior room.
Send reply to:    Offroad@off-road.com

On 10 Apr 97 at 1:12, Rusty Boling wrote:

> I understand that the trac loc unit has clutches which will can cause
> both wheels to pull but how does it know when to actually add more
> torque and to what limit.  What forces the clutches tighter together or
> does the friction modifier somehow expand when slippage occurs because
> of friction.  I understand that the clutches are always somewhat
> together so would this help prevent initial slippage?  Also, what is the
> maximun amount of torque that could be supplied  to either wheel?
> Thanks  Rusty Boling

First: the more simple friction plate LSD's do not even *vary* their 
lockup effect with more torque in the system. I believe these simple 
systems are even used in some 4x4's, as these are the ones that wear 
out the fastest in regard with effective operation.
Second: with variable friction clutch LSD's, the lockup variation is 
a straight result of torque in the system, not of the amount of 
slippage. Minimum torque in the system (one wheel airborn) leaves you 
with only the preload friction. A solution, similar to geared torque 
sensing diff's, is pulling the parking brake, to increase torque in 
the system.

Third, how do they work: I am not sure if all variable friction
plate LSD's work this way, but the general idea is a (left/right)
split cage inside the diff carrier. 
The shaft(s) on which the planet gears sit push the internal carrier
halfs outwards by use of cams or ramp angles (ramp angle in forward
direction can be different than in reverse direction, to provide
different lockup effects for accelleration and engine braking). This
outward movement pushes the clutches together and increases
friction. 
Preload is the initial friction without this ramp angle effect, ie 
when torque in the system is minimal (one wheel airborn).

For more stuff on Traction Aiding Devices, see a FAQ on my homepage:

http://www.a1.nl/phomepag/markerink/main_4x4.htm



-- 
Bye,

       _/      _/       _/_/_/_/_/       _/_/_/_/_/
     _/  _/  _/               _/       _/  _/  _/
     _/  _/ illem    _/     _/ an    _/  _/  _/ arkerink
                     _/_/_/  



      The desire to understand 
is sometimes far less intelligent than
     the inability to understand



[note: 'a-one' & 'en-el'!]




To:               Offroad@off-road.com
Date sent:        Thu, 10 Apr 97 08:54:02 EST
From:             "SandJC" 
Subject:          Re: Ford Trac Loc help and need 4x4 with interior room.
Send reply to:    Offroad@off-road.com

I understand that the trac loc unit has clutches which will can cause 
both wheels to pull but how does it know when to actually add more 
torque and to what limit.  What forces the clutches tighter together or 
does the friction modifier somehow expand when slippage occurs because 
of friction.  I understand that the clutches are always somewhat 
together so would this help prevent initial slippage?  Also, what is the 
maximun amount of torque that could be supplied  to either wheel?
Thanks  Rusty Boling

     It's a little hard to picture unless you have one in front of you, of 
     if you know how a standard open differential is put together.

     Think of it like this:  There are four spider gears in the center of 
     the carrier, all facing each other and all meshed together.  If you 
     rotate one of them they all go 'round.  They are straight cut beveled 
     gears that will all tend top push towards the outside if you jam them 
     up.

     For example, if you simply set them up on a table top meshed together, 
     hold one still and try to rotate another, they will tend to push 
     outwards until they un-mesh, right?  Well this is what's happening in 
     the diff.  Any torque going through the diff will tend to want to "jam 
     up" the gears, pushing them outward against the carrier.  

     The clutch plates are located between the gears and the carrier (just 
     the gears that are on the axles), so they are squeezed together.  The 
     plates have toothed edges that alternate from the inside to the 
     outside...the inside teeth mesh with the axle splines and the outside 
     teeth mesh with splines in the carrier, so the result is that the 
     carrier is locked to the axle.

     So, the answer is, the more torque going into the diff, the more 
     lockup.  This is why, when in very slippery conditions where ANY 
     torque causes a wheel to spin it can be helpfull to apply the parking 
     brake to jam those puppies up!

     Hope this helps...

     JoeSand

 
Date sent:        Thu, 11 Apr 1996 13:07:26 -0600 
To:               offroad@ai.gtri.gatech.edu 
From:             gwbuild@allwest.net (wakefield const.) 
Subject:          Re: Powerlock vs TrackLock ? 
Send reply to:    offroad@ai.gtri.gatech.edu 
 
 
> Can't tell you about the Powerlock vs. the Trac Lok, except to say that 
> I have a Trac Lok and it's very positive and works well... 
> The Trac Lok requires an additive called "Equatorque" which is a 
> friction modifier...  The instructions I got with the unit called 
> for 1 tube, or 4oz.  I don't know if it is a reducer or increaser, 
> but I know 80w-90 won't work correctly and you might risk damaging 
> the diff if the friction modifier isn't in there....   
 
        I use Equa-torque in my Power Brute LSD. Its supposed to decrease 
friction and helps keep the LS device from chattering....also supposed to 
lenghten life-span of the device.  
        If you get to a gnarly trail or plan on spending a weekend in the 
rocks where you need less slippage and more locker-like characteristics, 
just add some power steering fluid to you diff. Be careful, a little goes a 
long way and I usually change to fresh 80-90w before I go home or 
immediately upon returning. 
 
 
 
From:             Joe Valdez - Module build coordinator  
To:               offroad@ai.gtri.gatech.edu 
Subject:          Powerlock vs TrackLock ?   
Date sent:        Thu, 11 Apr 96 11:41:21 PDT 
Send reply to:    offroad@ai.gtri.gatech.edu 
 
Reply From jvaldez At 11:32A On Thu Apr 11 1996: 
 
> Is a Powerlock tighter than a Tracklock? 
> I just bought a 68 scout 44 rear axle that has a Powerlock 
> differential. I was wondering how it compares to other 
> limited slip diffs. Also, I was told to put the friction 
> modifier in. Six states distributors only had Ford m-19546-a 
> friction modifier; is it the same as chevy's? It is blue, and 
> chevy's was gold. I suspect it is just died blue. 
> Is one 4oz. bottle enough? 
> Does it reduce friction or increase it? I was thinking that I might 
> try just straight 80w 90 oild first and see if it pops around 
> corners. 
> Thanks, 
> Brent 
> bmoss@es.com 
 
 
Brent, that Powerlock of yours is a fine unit, it has 2 sets of clutches vs. 
 a limited slip which has one set, you can get your powerlock rebuilt with  
extra clutch packs and torqued down tighter than stock. This will give you a 
Powerlock that locks up just like a locker. 
  I run 140wt gear oil in my diffies and gear boxes, the 80-90wt stuff was  
just too thin for my tastes, especially all the desert wheelin we do out  
here. 
 
Joe Valdez, Scouts West/CA4WDC 
jvaldez@centon.com 
 

 

To:               Offroad@offroadlist.com
From:             "Willem-Jan Markerink" 
Date sent:        Fri, 29 May 1998 16:57:23 +0000
Subject:          Re: Front Lockers vs LSD's
Send reply to:    Offroad@offroadlist.com

On 28 May 98 at 9:28, Shaw, Steve wrote:

> Then I discovered the Truetrac isn't available for the Dana 60, so I'm stuck
> with a Dana Trak-Lok.  I called up Dana to find the specs on them and
> discovered they have a high initial bias (400 ft-lb) , and it only slightly
> increases with applied torque (up to a max of under 1000 ft-lb).  This is
> likely to effect my steering even in 2wd (with the hubs locked) and I could
> still potentially get stuck with only 3 wheels turning.

Very interesting data, the first time I see absolute numbers on
clutch platers (would LOVE to see similar data for other clutch
plate/cone brands!!)....though it also confirms my opinion that some
of these LSD's are not ment for packed snow and ice either....on
glare ice, the effect would be absolutely identical to a spool.

Btw, for the ease of understanding, assuming the engine is capable of 
400lbs-ft as well, and with a 40:1 total 1st/low ratio, it only has a 
bias of 10%, increasing to 25% when it manages to lock up (which 
assumes some traction on the least-grip wheel).
With lesser engines, this goes up to 20% and 50%.

Not bad, but not very sophisticated in winter either....



-- 
Bye,

Willem-Jan Markerink


      The desire to understand 
is sometimes far less intelligent than
     the inability to understand



[note: 'a-one' & 'en-el'!]

Summary Pro's & Con's