lockauto.htm Number of hits on this page:

About lockup converters in lower gears 


To:               Offroad@off-road.com
From:             Willem-Jan Markerink 
Date sent:        Fri, 9 May 1997 00:07:15 +0000
Subject:          Re: Locking auto, was: What's a trans. brake?
Send reply to:    Offroad@off-road.com

On  8 May 97 at 8:28, SandJC wrote:

>      While we are talking auto, there is another quesiton that I have never 
>      had answered properly:
>      
>      Some automatic transmission have an electical "lockup" feature that 
>      locks up the torque converter to bet better mileage on the freeway.  
>      Could one of these units be equiped with a manual switch to lock it up 
>      in any gear?  If so, auto's would be quite a bit more useful off road 
>      since you would have significantly more engine braking.
>      
>      Can this be done?  Has it?
>      
>      Joe Sand

I thought this might work also, but the follow tw messages were posted to 
r.a.4x4 recently:

1) xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
FROM: Jerry Steele 
SUBJECT: Re: 4WD: manual or automatic 700R-4 bs
DATE: Thu, 01 May 1997 20:00:13 -0700
ORGANIZATION: Starnet

OK, prepare for some internet bad manners with a huge post. You asked
for it though.

>coby hughey wrote:
> 
> In article , jsteele@azstarnet.com
> spouts...
> 
> >
> >This not only doesn't work but shouldn't be done. I've been there, done that, 
> >and if anybody wants the sordid technical details email me.
> >
> 
> This was a rather silly post.  You claim something, and don't back it up?  I'm
> curious; share what you know or don't tease us.  Why even post at all? If your
> experiences are 'too lengthy' for here, but ok to write multiple times via email,
> then I'm confused as to your intelligence....C'mon, don't insult us, inform us.
> 
When reading the following keep in mind that I learned all this because
I installed the switch to manually activate the lock up converter. When
it didn't work like I expected, here's what I learned:

WHY IT DOESN'T WORK

The hydraulic system of the 700R-4 is designed in such a way that the
torque converter lock-up circuit only has sufficient hydraulic pressure
to enable lockup at speeds above approximately 30 mph in either 3rd or
4th gear. All the electrical solenoid does is act as the valve to enable
this circuit or completely turn it off. The transmission is designed
this way because the automakers MUST NEVER have a lockup while the
vehicle is stopped. To depend on the electrical circuit alone is not
enough. The reason the oems must do this is that would stall the engine
potentially interfering with operation of power brakes and steering.
Ford knows all about this as some of their early lockups didn't prevent
that. Because the hydraulic circuit requires sufficient speed to develop
sufficient pressure in this circuit for this to happen, you cannot
modify the hydraulic circuit to cause a lockup.

WHY IT SHOULDN'T BE DONE EVEN IF IT WORKED

One of the reasons they use a vacuum valve, or a computer signal to
control the lockup is to release the lockup ASAP when some throttle
(read: torque) is called for. The reason is that the lockup mechanism
(you have to take a torque converter apart and see one to really
realized the significance of this) is a very light duty mechanism. So
they engage it only under light cruise loads.

Anyone who owns a 700R-4 is also familiar with the _ throttle downshift.
What does this have to do with the torque converter? The 4th gear of the
700R-4, like overdrives in most everything, is again not designed for
hard use and they want it to kick out whenever torque is demanded
(direct 1:1 gears in any transmission, manual and automatic, are the
toughest). One auto tranny builder for some time offered a kit to defeat
this downshift, I notice it's no longer around. I suspect that after
enough people wrecked their 700R-4's they realized that maybe, just
maybe, GM's engineers were smarter than them and had a reason for the
way the 700R-4 is designed. This just demonstrates that when GM wants
the torque converter unlocked, it's best to leave it that way.

As a final note, with low enough gears (I run a 2.6 transfer case and
4:88 gears) the downhill braking of a 700R-4 is superb. You have to
experience it to believe it (but still not as good as a good manual
setup).

2)xxxxxxxxxxxxxxxxxxxxxxxxxx

FROM: Jerry Steele 
SUBJECT: Re: 4WD: manual or automatic 700R-4 bs
DATE: Fri, 02 May 1997 11:36:10 -0700
ORGANIZATION: Starnet

> Well, let me say that you're right in that it *shouldn't* be done... 
> BUT while on the 700R4 if the torque converter has the later style 
> input shaft (th350 size) and the clutches are good enough behind a 
> mild small block the motor will stall if it is locked up, and the 
> brakes are applied.... Now there are pro's and cons either way you 
> go...

You can't lock a 700R-4 just by activating the solenoid. The hydraulic
system cannot engage the torque converter clutch at low speeds and
stopped. It is simply impossible to do it if you wanted to.

I'm one of the ones who's tried this and shed blood getting into the
700R-4 to understand it.
xxxxxxxxxxxxxx


-- 
Bye,

Willem-Jan Markerink


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



[note: 'a-one' & 'en-el'!]
But to be honest, there are devices that have worse compression braking than auto's....:-)) 
To:               Offroad@off-road.com
Date sent:        Wed, 18 Jun 1997 08:03:23 -0600
From:             tim@ai.com (AI, Welden, Timothy W)
Subject:          Re: 4x4 Hovercraft??
Send reply to:    Offroad@off-road.com

And you all thought auto trannys were bad at compression braking on
those long downhills... :^)

-Tim-
'80 CJ-5
MHJC Patrol-16



To:               Offroad@off-road.com
From:             Willem-Jan Markerink 
Date sent:        Wed, 18 Jun 1997 21:36:53 +0000
Subject:          Re: 4x4 Hovercraft??
Send reply to:    Offroad@off-road.com

On 18 Jun 97 at 8:03, AI, Welden, Timothy W wrote:

> And you all thought auto trannys were bad at compression brakeing on
> those long downhills... :^)

Ah, but you can (must) put the hovercraft in reverse in that case!....8-))
Not sure whether an auto tranny likes that....:-))



-- 
Bye,

Willem-Jan Markerink


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



[note: 'a-one' & 'en-el'!]
Upon which, many moons later, there came an interesting note/warning against this 'putting tranny in reverse when going downhill': 

To: 80 Series Owners Online <80_series@palladium.corp.sgi.com> 
Subject: [80] Aussie 4wd handbook 
Sender: owner-80_series@palladium.corp.sgi.com 
Reply-To: 80_series@palladium.corp.sgi.com

Had a look at the 4wd handbook recently released by Tread Lightly here
in Victoria. There's a major boo boo in there about engaging reverse
gear in an automatic to offer additional engine braking when descending
(forwards) steep downhills....

Don't do it.

On an 80, especially '93 on (as with most modern vehicles with an ecu),
the ecu shuts the motor down when it senses continued forward motion
when in reverse and/or exceeds a certain speed. You lose engine braking
(it free wheels), brake booster (you can't stop), power steering (you
can't steer) and heaven forbid, the airconditioning (your drink in the
factory cup holder gets warm ;-)

I have a warning page on our web site. Also notified Tread Lightly as a
matter of courtesy some time ago but they didn't respond.

Cheers
gc

-- 
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* George Couyant                           _                     *
* High Performance Technology Consultant   O                     *
* Silicon Graphics Pty Ltd                 The man from Aus.  *
*                                        _/ \_                   *
* Tel   : +61 3 9882 8211                                        *
* Fax   : +61 3 9882 8030     mobile: 0419 337 692               *
* http://www.sgi.com.au       e-mail: georgec@melbourne.sgi.com  *
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From:             "Willem-Jan Markerink" 
To:               80_series@palladium.corp.sgi.com
Date sent:        Thu, 29 Jan 1998 17:51:51 +0000
Subject:          Re: [80] Aussie 4wd handbook
Priority:         normal
Send reply to:    80_series@palladium.corp.sgi.com

On 29 Jan 98 at 14:19, George Couyant wrote:

> Had a look at the 4wd handbook recently released by Tread Lightly here
> in Victoria. There's a major boo boo in there about engaging reverse
> gear in an automatic to offer additional engine braking when descending
> (forwards) steep downhills....
> 
> Don't do it.

In an r.a.4x4 thread about the difference in traction when going uphill 
vs downhill, I proposed throwing it in reverse downhill, to obtain 
the same thread-cleaning effect as when spinning tires uphill.
It did not meet much enthousiasm....:-))

> On an 80, especially '93 on (as with most modern vehicles with an ecu),
> the ecu shuts the motor down when it senses continued forward motion
> when in reverse and/or exceeds a certain speed. You lose engine braking
> (it free wheels), brake booster (you can't stop), power steering (you
> can't steer) and heaven forbid, the airconditioning (your drink in the
> factory cup holder gets warm ;-)

Ha, only sissies need a booster to steer and brake!....:-))
Now the AC, that is a more severe problem....

> I have a warning page on our web site. Also notified Tread Lightly as a
> matter of courtesy some time ago but they didn't respond.

Oh btw, this reverse trick worked great when I was in the Dutch army.
I was driver of an ambulance track, and as para-medics, we had very
little supervision. We were actually the only track/tank drivers in
the entire army without someone higher in rank on the vehicle (I
wasn't very good at distinguishing stripes from stars anyway, so no
complaints from me....:-)).

Apart from making pirouettes on snow and ice untill we became 
dizzy(*), we had another stage performance for boring afternoons. 
With the engine being front mounted, it was a bit nose-heavy....it
also had a 3sp automatic that had no silly interlocks between
forward and reverse gear (like stepping on brakes)....actually, 1st
forward and reverse were on opposite ends of the handle....now, in
an ordinary vehicle there would be no fun in rocking this handle
back and forth....all you would do is squeek some tires....but with
this nose heavy thing, throwing it from 1st forward into reverse had
the cute side effect of lifting the rear of the vehicle more than
one meter off the ground. Not that a 14 ton vehicle falling back to
earth from this distance was boring either. It really broke those
boring afternoons. I still think it was better than finding guinnee
pigs for pseudo-medical operations....:-))

Oh, after a few weeks we got stranded with one of these tracks....had
to be towed back from the middle of nowhere behind a
recovery-Leopard....we all were a bit dissapointed in the durability
of automatics actually. But being towed by a Leopard was fun. I
never forget the absolute lack of sight driving behind such a
massive coal burner.

(*) if someone says that 4-wheel drive and 4-wheel steer on snow is
the ultimate kick: they have no clue what they are talking
about!....2-track is far more brilliant for vehicle control....any
traction, no matter how small, means instant direction
control....even if you are spinning around at 100rpm, you still have
some influence on the average direction in which the pirouettes are
taking you!....:-))


-- 
Bye,

Willem-Jan Markerink

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


[note: 'a-one' & 'en-el'!]
From: Steve Shaw To: "'w.j.markerink@a1.nl'" Subject: Lockup Converters Date sent: Sat, 2 May 1998 23:04:40 -0400 I just read your "Tech Stuff" on lockup converters and thought I'd point out an almost error stated in there about 700R4's. BTW, Very impressive source for locker/lsd information. I just installed one in my rig, the transmission was originally from a 1991 ½ ton 4x4 full size pick-up. There is nothing that stops the lockup from engaging within this tranny. As soon as 12 volts is applied between contact points A & D it locks up; in any gear (even reverse) and at any speed. I rigged up a switch to lock it up and with my initial setup, if you flipped the switch while stopped in drive the truck would lurch and the engine would stall. I also have a 1983 700R4 and this one has an internal pressure switch that only allows it to lock up (when power applied) in 3rd and 4th gear (this was actually what I wanted). I discovered that in 91 & 92 they used the main engine computer to control the lock-up and removed the "safety" feature. The computer would actually lock up the torque converter if run is any gear under low load for a certain period of time. Older 700R4's can easily be modified to bypass the pressure switch. Steve To: Offroad@offroadlist.com From: "Shaw, Steve" Subject: Manual vs Automatic Date sent: Thu, 28 May 1998 09:06:02 -0400 Send reply to: Offroad@offroadlist.com Regarding push starting of a modern automatic, unfortunately all of the clutches and bands are hydraulically applied, including the torque converter. The only way I can see setting up an auto for push starting would be to have a small hydraulic pump sucking tranny fluid out of the pan and pumping it into the main pressure line in the tranny (you could pump it through the main line test port on the side). At this point you could put the gear selector in 1st and push away. At a high enough speed the torque converter would turn the engine over. The other option that should work is to rig up a switch to energize the valve for the lockup torque converter (they should still lock with reverse torque). You'd obviously still need a battery to do this, but you'd be able to start with a bad starter or somewhat low battery. Some other posts talked about damaging the torque converter and torque converter fins driving with it locked up. Having pulled one apart (from an old Chrysler tranny), I don't see what the gear or speed has to do the damaging the torque converter. All the lockup is is a simple clutch and friction surface at the front end of the converter. I've heard they are only designed for a limited amount of torque, so you probably couldn't go flooring it without slipping and wearing the lock-up clutch. My 1991 700R4 does lock up in any gear (including 1st and reverse) as soon as power is applied between the A and D pins on the tranny connector, so it would be simple to set up for rock crawling. I know this works because when I first installed the unit I rigged up a switch to lock it up. I assumed it would only lock in 3rd and 4th like the older 700R4's, instead the instant I switched the switch if I was stopped in gear the truck would lurch and the engine would stall. Basically with the unit I have there are no hydraulically activated electrical switches attached to the valve body in line with the lock-up solenoid. Steve S Date: Thu, 17 Jun 2004 08:13:49 +1000 Subject: Re: [DTLC] AT Valve Body replacement and Lock up From: Brian and Sandra Monger To: dtlc@helios.net Reply-To: dtlc@helios.net On Thursday, June 17, 2004, at 06:59 AM, w.j.markerink@a1.NL wrote: > On 16 Jun 2004 at 16:15, Greg Goulden wrote: > >> Al, >> >> Lock up refers to the ability to be able to lock the torque converter, >> so that you get full 1:1 drive rather than the usual % slippage, which >> when on the road translates to more efficiency, less fuel, etc. > > Don't forget engine-braking! there is a shop near here that modifies torque converters so they are fully locked in overdrive (ie wheels driving the engine) so the engine braking performance is the same as for a manual vehicle. downside is you lose the forward lockup but this can actually be a blessing - see text in the link. http://www.outerlimits4x4.com/PHP_Modules/phpBB2/viewtopic.php?p=200654 cheers Brian To: Brian and Sandra Monger Cc: 80scool_aus@yahoogroups.com, 80scool@yahoogroups.com, "extreme_trans" , zillys@gmx.de From: "Willem-Jan Markerink" Date: Thu, 17 Jun 2004 02:40:21 +0200 Subject: [80] Re: AT Valve Body replacement and Lock up Reply-To: 80scool@yahoogroups.com On 17 Jun 2004 at 8:13, Brian and Sandra Monger wrote: [thread discussing the AT-valve-body replacement from http://www.automatictransmission.com.au/release.asp?NewsId=11360 snipped] > On Thursday, June 17, 2004, at 06:59 AM, w.j.markerink@a1.NL wrote: > > > On 16 Jun 2004 at 16:15, Greg Goulden wrote: > > > >> Al, > >> > >> Lock up refers to the ability to be able to lock the torque > >> converter, so that you get full 1:1 drive rather than the usual % > >> slippage, which when on the road translates to more efficiency, > >> less fuel, etc. > > > > Don't forget engine-braking! > > there is a shop near here that modifies torque converters so they are > fully locked in overdrive (ie wheels driving the engine) so the engine > braking performance is the same as for a manual vehicle. downside is > you lose the forward lockup but this can actually be a blessing - see > text in the link. > > http://www.outerlimits4x4.com/PHP_Modules/phpBB2/viewtopic.php?p=200654 [url changed slightly to fit in 1 line] First: To avoid confusion I would call that situation 'overrun' instead of 'overdrive'....;)) (with 'accelerating' & 'coasting' as the only two other options) Second: Interesting concept, but doesn't a normal lockup-converter stay locked above a certain rpm, regardless whether accelerating or decelerating? I also fail to see why such an overrun-clutch couldn't work in the other direction as well, unless the forces require a mono-directional design/friction-lining/whatever. And their point of keeping wear/tear/vibrations from the rest of the drivetrain by not having a lockup, in particular when towing, is offset by *much* more heat being generated.... CC to 80-lists & Rodney @Automatic Transmissions. Willem (still also charmed by the variable-vane-pitch torque- converters from the old days, with two different stall-speeds/stall- ratio's) Jan PS: I dig this one too: http://makeashorterlink.com/?D11F23598 (which is perhaps related to this? http://www.permo-drive.com/ ) And this is interesting too: http://www.autofieldguide.com/articles/100304.html -- Bye, Willem-Jan Markerink The desire to understand is sometimes far less intelligent than the inability to understand [note: 'a-one' & 'en-el'!] To: 80scool@yahoogroups.com From: Brian and Sandra Monger Date: Thu, 17 Jun 2004 11:00:10 +1000 Subject: Re: [80] Re: AT Valve Body replacement and Lock up Reply-To: 80scool@yahoogroups.com On Thursday, June 17, 2004, at 10:40 AM, Willem-Jan Markerink wrote: > On 17 Jun 2004 at 8:13, Brian and Sandra Monger wrote: >> >> there is a shop near here that modifies torque converters so they are >> fully locked in overdrive (ie wheels driving the engine) so the engine >> braking performance is the same as for a manual vehicle. downside is >> you lose the forward lockup but this can actually be a blessing - see >> text in the link. >> >> http://www.outerlimits4x4.com/PHP_Modules/phpBB2/ >> viewtopic.php?p=200654 > > [url changed slightly to fit in 1 line] > > > First: > To avoid confusion I would call that situation 'overrun' instead of > 'overdrive'....;)) > (with 'accelerating' & 'coasting' as the only two other options) overrun describes the situation where a driven shaft is going faster than its driving shaft; like when you coast on a pushbike - even if you pedal slowly - there is no drive between the pedals and the wheel because the wheel is overrunning. overdrive is the correct term for the situation we are describing, so to avoid confusion it's probably best to use the correct terms. what you call 'coasting' is the same as 'overdrive' (what you want to call 'overrun') unless you put the trans in neutral to truly 'coast'. > Second: > Interesting concept, but doesn't a normal lockup-converter stay > locked above a certain rpm, regardless whether accelerating or > decelerating? no - see GG's description. the lockup clutch in a torque converter is nowhere near strong enough to transmit high torque, and almost never comes into play in engine braking. > I also fail to see why such an overrun-clutch couldn't work in the > other direction as well, unless the forces require a mono-directional > design/friction-lining/whatever. the overrun clutch used to modify converters for engine braking is a sprag clutch. a ratchet if you like. it is one-directional. almost identical in function to the sprocket clutch on a pushbike. > And their point of keeping wear/tear/vibrations from the rest of the > drivetrain by not having a lockup, in particular when towing, is > offset by *much* more heat being generated.... when you're towing, you spend a lot more time with the converter in unlocked mode (maybe not in NL where there are no hills eh? ;) towing generates a lot of heat in autos regardless - and it's not really a mod you'd consider for a tow rig, it's more for dedicated offroaders. personally I'm a three-pedal fan, but I think it's pretty cool that you can build an auto to provide the best of both worlds. cheers Brian To: 80scool@yahoogroups.com Cc: dtlc@helios.net, 80scool_aus@yahoogroups.com, extreme_trans , zillys@gmx.de From: "Willem-Jan Markerink" Date: Thu, 17 Jun 2004 04:06:06 +0200 Subject: [80] Re: AT Valve Body replacement and Lock up Reply-To: 80scool@yahoogroups.com On 17 Jun 2004 at 11:00, Brian and Sandra Monger wrote: > On Thursday, June 17, 2004, at 10:40 AM, Willem-Jan Markerink wrote: > > > On 17 Jun 2004 at 8:13, Brian and Sandra Monger wrote: > >> > >> there is a shop near here that modifies torque converters so they are > >> fully locked in overdrive (ie wheels driving the engine) so the engine > >> braking performance is the same as for a manual vehicle. downside is > >> you lose the forward lockup but this can actually be a blessing - see > >> text in the link. > >> > >> http://www.outerlimits4x4.com/PHP_Modules/phpBB2/ > >> viewtopic.php?p=200654 > > > > [url changed slightly to fit in 1 line] > > > > > > First: > > To avoid confusion I would call that situation 'overrun' instead of > > 'overdrive'....;)) > > (with 'accelerating' & 'coasting' as the only two other options) > > overrun describes the situation where a driven shaft is going faster > than its driving shaft; like when you coast on a pushbike - even if you > pedal slowly - there is no drive between the pedals and the wheel > because the wheel is overrunning. > > overdrive is the correct term for the situation we are describing, so > to avoid confusion it's probably best to use the correct terms. what > you call 'coasting' is the same as 'overdrive' (what you want to call > 'overrun') unless you put the trans in neutral to truly 'coast'. To me coasting means equal rpm, no load in either direction.... And 'overrun' at least the *attempt* from the wheels to overrun the engine....that they *can't* with a lockup-device is something else. > > > > Second: > > Interesting concept, but doesn't a normal lockup-converter stay > > locked above a certain rpm, regardless whether accelerating or > > decelerating? > > no - see GG's description. the lockup clutch in a torque converter is > nowhere near strong enough to transmit high torque, and almost never > comes into play in engine braking. I thought about strength, but that would have to be assymetrical then, as under full load/acceleration the torque is even larger than during 'overrun' (perhaps equal with jake-brake stuff?). > > I also fail to see why such an overrun-clutch couldn't work in the > > other direction as well, unless the forces require a mono-directional > > design/friction-lining/whatever. > > the overrun clutch used to modify converters for engine braking is a > sprag clutch. a ratchet if you like. it is one-directional. almost > identical in function to the sprocket clutch on a pushbike. Ah, okay....so you need two of those in series....in some braincracking way....:)) > > And their point of keeping wear/tear/vibrations from the rest of the > > drivetrain by not having a lockup, in particular when towing, is > > offset by *much* more heat being generated.... > > when you're towing, you spend a lot more time with the converter in > unlocked mode (maybe not in NL where there are no hills eh? ;) towing > generates a lot of heat in autos regardless - and it's not really a mod > you'd consider for a tow rig, it's more for dedicated offroaders. Still, it would be heaps more efficient (thermically) to downshift one gear, and lockup again, instead of a higher gear and the convertor pumping (heat). > personally I'm a three-pedal fan, but I think it's pretty cool that you > can build an auto to provide the best of both worlds. We first need full manual shift-control on Cruiser slusboxes....:)) -- Bye, Willem-Jan Markerink The desire to understand is sometimes far less intelligent than the inability to understand [note: 'a-one' & 'en-el'!] From: "Hudson-Davies Family" To: Subject: Re: AT Valve Body replacement and Lock up Date: Thu, 17 Jun 2004 16:04:19 +1000 Hi Willem it's Rodney here from Wholesale Automatics. First of all thanks for bring this message to my attention. I have read all the responses and even gone to the web site message board that started this and read through all of there messages. Where do I start? I would first of all like to let you know that removing a Lock-Up from any convertor in a vehicle that is as heavy as a Landcruiser or Nissan Patrol will shorten the life span of the transmission due to over heating especially when towing. This can be as bad as only getting 5,000Km out of your transmission after removing the Lock-Up. It can't be done, I know! I have already been there and done that years ago. I have a full time job trying to stop these things from over heating at the best of times. The worst offender is the A440 hydraulic transmission but they all do it to some degree because of the small size of the convertors that are used in all Landcruiser and Patrols. You can not afford to remove one of the major components that keeps the transmission within an expectable heat range ( 60-120C ). We have built many low stall convertors and it took as 3 years to work out how to lower the stall speed without having to enlarge the convertors outer circumference or having to remove the Lock-Up plate. I tell you this with a passion because we have reconditioned, modified and changed these transmissions so much over the last several years that I know them inside and out. I know how they will respond when you fit a Turbo or do a V8 conversion. I know what sort of a heat to expect from a certain transmission on a 34 degree day towing a 24 foot long caravan with a standard engine going through the mountains or even across the Nullarbor. Just as a twist to this story and to prove a point I have just got off the phone to a customer of mine that has a GU Patrol and noticed lack of power in the engine, struggling to maintain 80 Km and a transmission that was getting over 125C on a flat stretch of road between Echuca and Deniliquin towing a caravan. We had fitted one of our standard reconditioned transmissions, Extreme valve bodies and our new transmission oil temp gauge kits several months ago for his trip to the Cape and also left him with sticked instructions to pull over if he ever got to 140C. He was concerned at 125C and rang me, I asked him to change from Gas to Petrol and with in 4 minutes the transmission was back down to 80C he speed was back up to cruising speed and had all his power back. What had happened was that he was holding his foot on the go peddle so much that the convertors Lock-Up was wasn't getting a chance to engage. No Lock-Up and the transmission was in trouble straight away! Needless to say he has a problem in the gas system some where (Should of asked him if lack of it was the problem!) I'll find out later. We can lower the stall speed of the convertor without having to remove the Lock-Up and in the lasts month or two decided that we no longer do this unless an V8 Conversion is being done, In this case the Low Stall Convertor is a must otherwise the convertor will overheat due to the high stall speed. The more power you have the higher the stall speed goes. We have instead developed a Lock-Up Manuel Over-Ride Control Relay, Switch and wiring harness that comes ready to install into all Toyota Land Cruiser and Nissan Patrols. Please see Link to news release for full details. Reducing the stall speed of the convertor behind a factory fitted Engine resalts in sluggish take off's, The stall speed drags the engine Rpm down to far on a Std factory engine. We spent a long time trying to find the fine line between better engine braking and sluggish take off's. We instead designed the lock-Up Over-Ride and got the best of both worlds. Steep down hill docents with 100% engine braking and no overrunning what so ever. One side effect if you can call it that is that the A442F transmissions will require the Extreme Valve Body as well, The Patrols don't need the valve Body for this and I haven't done one for the A750F 5 Sped yet. Looking for a guineapig! In my eyes he perfect heavy duty accuracy pack for both the Land Cruiser and Patrol Automatic Transmission is: Extreme Recalibrated Valve Body: http://www.automatictransmission.com.au/release.asp?NewsId=4651 http://www.automatictransmission.com.au/release.asp?NewsId=8169 http://www.automatictransmission.com.au/release.asp?NewsId=11360 And the A750F 5 Speed that I have photos of but not made a news release for yet. I think Greg Goulden would kill me if I didn't give it to him first as promised. Works great but! Temp Gauge Kit: http://www.automatictransmission.com.au/release.asp?NewsId=12031 Lock-Up Manuel Control Unit: http://www.automatictransmission.com.au/release.asp?NewsId=12101 Large Oil Cooler if not already fitted: Synthetic Transmission Oil: If you or anybody have any questions regarding this matter then please feel free to ring me direct on 0415393755. As you can imagine there is no possible way I can explain all the fine details without boring every body to tears. Please feal free if there is something I did a useless job of explaining. :) And in the case of Greg feel free to edit the links out. I will understand! Kind Regards Rodney Hudson-Davies Wholesale Automatic Transmissions To: 80scool@yahoogroups.com From: Brian and Sandra Monger Date: Thu, 17 Jun 2004 12:32:18 +1000 Subject: Re: [80] Re: AT Valve Body replacement and Lock up Reply-To: 80scool@yahoogroups.com On Thursday, June 17, 2004, at 12:06 PM, Willem-Jan Markerink wrote: > On 17 Jun 2004 at 11:00, Brian and Sandra Monger wrote: > >> >> On Thursday, June 17, 2004, at 10:40 AM, Willem-Jan Markerink wrote: > > I thought about strength, but that would have to be assymetrical > then, as under full load/acceleration the torque is even larger than > during 'overrun' (perhaps equal with jake-brake stuff?). torque converter clutches do not lock up under hard acceleration either - when you floor the go pedal, the converter unlocks. >> the overrun clutch used to modify converters for engine braking is a >> sprag clutch. a ratchet if you like. it is one-directional. almost >> identical in function to the sprocket clutch on a pushbike. > > Ah, okay....so you need two of those in series....in some > braincracking way....:)) it's not really that complicated. go right back to torque converters 101: the impeller blades are attached to the inside of the case. the turbine blades are attached to the transmission input. ignore the stator for now. for drive to get from the engine to the transmission relies on the ATF being thrown against the turbine by the impeller. there is no mechanical connection between the turbine (transmission input shaft) and the flywheel (impeller). now place a ratchet between these previously completely unconnected parts such that the transmission input will never be able to go faster than (ie overrun) the flywheel. it can still go slower - so under stop and accelerate conditions, the torque converter functions as a regular one - with some slip - driving the transmission. as soon as the engine tries to go slower than the transmission input (lift foot off go pedal), the ratchet prevents the engine turning slower than the transmission input - voila, you have manual-style engine braking. >> when you're towing, you spend a lot more time with the converter in >> unlocked mode (maybe not in NL where there are no hills eh? ;) towing >> generates a lot of heat in autos regardless - and it's not really a >> mod >> you'd consider for a tow rig, it's more for dedicated offroaders. > > Still, it would be heaps more efficient (thermically) to downshift > one gear, and lockup again, instead of a higher gear and the > convertor pumping (heat). if you are accelerating/driving hard enough to downshift guaranteed the converter will not be locked, and will not lock again until you ease off. the lockup does not function under hard acceleration. like I said - you wouldn't do it to your tow rig. >> personally I'm a three-pedal fan, but I think it's pretty cool that >> you >> can build an auto to provide the best of both worlds. > > We first need full manual shift-control on Cruiser slusboxes....:)) want manual? get three pedals ;) cheers Brian http://www.pirate4x4.com/forum/showthread.php?t=280963 xxxxxxxxxxxx Some of the guys with 6.5TDs and 4L80-Es use a resitor to make the tranny think it's hot when it's not, which forces lockup down to lower RPM and increases line pressure. Here's the scoop from jeffreydmet on some other site: "I found out that if the thermistor in the transmision is working correctly and it senses a temperature over 284 deg F then the trans will go into hot mode, freeze the shift adapts and record in history the code for a hot trans. It will not turn on the service engine soon light. So what I did was to wire a switch so that a 50 Ohm resistor could be switched in and out of a parallel circuit with the transmision thermistor. What this does is trick the PCM into thinking the trans is close to 300 deg in temp so it works the TCC in hot mode. The goal is to make it think its hot without thinking that the thermistor circuit is shorted. Also I wired in an LED to the TCC solenoid so I could tell when the PCM was calling for the TCC to be locked. Here's what happened with the switch on. The TCC will lock with the trans shift lever in second when it exceeds about 25mph. Also the TCC is used longer, more frequently and under higher throttle in 3rd and 4th. It still goes off when a shift is made. Also when slowing down the TCC will stay locked until you let almost completely off of the accelerator pedal. Shifts were still smooth. I did see one thing though that needs to be watched out for. In some situations with a very heavy pull such as accelerating hard up a hill the TCC may continue to slip until it can catch up. What you need to do in this case is slack off the throttle until the TCC completely locks up then reapply throttle. It will then hold the big load." I haven't tried it, but he likes it. From: "Robyn Church" To: Subject: 700R4 Auto Lockup Date: Wed, 29 Dec 2004 07:24:21 -0800 Well I have read most of the posts here about the lockup on the 700R4 Most of the folks are pretty close to the real deal. However if you have a later 700 that has a valve body that still has the Hydraulic valving or at least the bore to install it into you can set the tranny up to run lockup in 2-3-and 4 and it will shift into lockup at about 30 to 35 under light throttle and drop out on compression decel at about 25. All that is needed is the 4-3 downshift valve and the 4th clutch valve and wire these as a type 2 (Most tech books list the types) run 12V to the 2 leads on the tranny plug and the little critter will work fine and you wont hurt it. The engineering that went into this box is at best questionable as there are still many areas that are weak even when you put all the after market goodies in. overall if built to the max this box will handle 350-400 HP with the use of a little restraint. If you need the ultimate tranny the 400 is tough to beat. I am using a 700 in a Humvee replica only because it gives me the 3.06 1st gear and the overdrive to allow my 6.2 diesel to get some good mileage. Just thought I would contribute. Robyn church. I post a lot at H1 forum.com



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