FROM: w.j.markerink@a1.nl (Willem-Jan Markerink)
SUBJECT: Re: Sway Bars?
DATE: Tue, 09 Jun 98 14:10:00 GMT
ORGANIZATION: A1 de Internet Provider uit Twente B.V.
NEWSGROUPS: rec.autos.4x4

In article <6li0of$knm$1@nnrp1.dejanews.com>, bfoust@my-dejanews.com wrote:
>In article 
,
>  Al Ordonez  wrote:
>>
>>
>> What is the function of the rear sway bars?
>> Thanks!
>> -Al
>>
>>
>
>Rear sway bars are used to keep the tires pressed to the ground more 
evenly.
>In vehicles that have them, they would be overly prone to spinouts without
>them.

How a tire is pressed to the ground only depends on how fast you go through 
a corner. It doesn't press the inside tire down more firmly, not will it 
prevent spinning....actually, being offroad in axle-twisting situations, 
there is nothing that will promote spinning *more* than a stiff set of 
anti-sway bars (ASB). That's why sway-bar disconnects were invented (the 
Nissan Patrol even has a remote operated rear ASB)

The only thing an anti-sway bar does it keeping the axle more in line with 
the vehicle....but once you go too far, it lifts off immediately and you 
are facing a tipp-over. In a non-ASB vehicle you would have been warned 
much earlier by the extreme body roll....making you so uncomfortable that 
you won't corner nearly as fast.

Many older Land Cruisers didn't have a rear ASB, and Land Rovers never had 
any ASB for a long time, even on coil spring vehicles (leaf springs are 
inherently more stiff to start with, and don't need it as bad to keep the 
vehicle level).

--
Bye,

Willem-Jan Markerink


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



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

FROM: vlad.kozlovsky@usa.net
SUBJECT: Re: Sway Bars?
DATE: Wed, 10 Jun 1998 20:12:11 GMT
ORGANIZATION: Deja News - The Leader in Internet Discussion
NEWSGROUPS: rec.autos.4x4,rec.autos.misc

Al,

> What is the function of the rear sway bars?

While reading through the replies, I noticed that while poeple were covering
this question pretty nicely, all of them neglected to mention an important
function of sway bars. Sway bars are used not only to reduce body roll in
corners, but also to tune the car's handling. It is actually the easiest way
to drastically change the way a car behaves during cornering. Basically the
stiffer end of the car will tend to lose traction sooner (I really should say
the tire slip angles will be higher at that end, but than I would have to
define them :) An anti-sway bar makes an end stiffer. The bigger/stiffer the
bar -- the stiffer it makes its end of the car. Most cars in the US are sold
with built-in understeer. It is safer this way because if a driver overcooks
a corner -- only natural, instinctive inputs are required to return the car
to its path. I.e., the driver has to apply his brakes and steer into the turn
(it's actually beneficial to steer less, but that's not what an average
driver will do). Very few cars in the US today will actually oversteer at the
limit. When a car oversteers, its rear will slide to the outside of the turn,
making the car turn more quickly. This makes the car turn A LOT better. It is
also much more dangerous for an inexperienced driver, since the required
correction to avoid a spin feels very unnatural and definitely takes some
practice. To prevent a spin-out the driver has to countersteer (meaning that
the steering wheel has to unwind and be turned in the opposite direction) and
KNOW what to do with the pedals. If he touches the brakes (which is probably
what 90% of people would do), he is practically guaranteed to loose it and
spin out completely. In most cases one has to accelerate, how hard depends on
the driven wheels. With rear wheel drive the acceleration must be very
slight, just enough to shift some weight to the rear tires. With front wheel
drive it is OK to give it a little more gas, but not too much or the front
end will get loose. With 4WD/AWD you accelerate as hard as you can and the
center diff takes care of the rest (unless it's an OPEN center diff) :)

Anyway, a rear sway bar makes the rear end of the car stiffer, reducing
understeer and increasing oversteer. If you put a stiffer rear bar on a car
that understeered a lot, you will cure some or all of that understeer and
might even induce some oversteer. The best is usually neutral -- so the car
drifts out at both ends. That's the fatsest way around a corner. The problem
arises when using things like limited-slip differentials, which tend to make
the car understeer at the limit no matter what you do with the bars. There is
also a ton of other things that affect cars balance. You can read about them
in many car handling books if you are interested.

Vlad.

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FROM: sbest@glinx.com (SBest)
SUBJECT: Re: Sway Bars?
DATE: Fri, 12 Jun 1998 12:24:23 GMT
ORGANIZATION: very little
NEWSGROUPS: rec.autos.4x4

>In article ,
>  Al Ordonez  wrote:
>>
>>
>> What is the function of the rear sway bars?
>> Thanks!
>> -Al
>>
>>
bfoust@my-dejanews.com wrote:
>Rear sway bars are used to keep the tires pressed to the ground more evenly.
>In vehicles that have them, they would be overly prone to spinouts without
>them.

  Actually this is the not quite the case.
Rear swaybars are used to limit the amount of body lean on
cornering while escaping the use of overly stiff springs AND
to balance the handling from front to rear.

  The addition of a rear swaybar will increase the tendency
toward oversteer (the rear end swinging about on cornering
limit) so that they are usually added to reduce understeer
("plowing" at cornering limit), often to balance the
addition of an extra heavy front swaybar.

  They might be a benefit to highway driving but are a major
hinderance to offroad travel on rugged unlevel terrain.



Steve Best, Nova Scotia, sbest@glinx.com
4 wheel drive van webpage:
http://www.glinx.com/users/sbest
Tire chains, camping gear, Bronco and some shooting stuff too...






FROM: sbest@TAKEOUTglinx.com (sbest)
SUBJECT: Re: Sway Bars
DATE: Sun, 22 Oct 2000 16:48:39 GMT
ORGANIZATION: Newsfeeds.com http://www.newsfeeds.com 80,000+ UNCENSORED Newsgroups.
NEWSGROUPS: rec.autos.4x4

On Tue, 24 Oct 2000 21:02:05 GMT, "Maximum Frog"
 wrote:

>I was wondering what thoughts are on the 4x4's that have front and rear sway
>bars.  

  I don't like them on off-road oriented trucks. Off-road trucks are not
sports cars and never will be. If your truck is for on-highway always ,
perhaps used for towing or bad weather, then they might be a good idea.

>As far as I know, most of them are not able to be disconnected unless
>they are some sort of aftermarket thingy.  

  Aftermarket, home-made, or removed with a wrench.

>Do they decrease the >articulation?  

  YES! 

>Does it really matter if you have IFS?  

  Some IFS seems to benefit greatly from swaybars. Swaybars increase
roll-stiffness and have an important bearing on understeer/oversteer. 
Some IFS systems are very affected by body roll ruining camber whereas a
solid axle is not at all. 

>What about the rear 
>that's still solid axle? Does that get any movement reduction by the bar?

  Yes if it has a rear swaybar installed too. A swaybar on the rear tends
to increase oversteer, an unstable and potentially dangerous tendency for
the rear to swing around unless corrected for. Therefore a rear swaybar is
usually balanced with a stiffer front swaybar. 

>What's good and bad about removing it?  

  Many heavy duty vehicles have a stiff front swaybar to balance the heavy
springs in the rear. Removing the front swaybar might cause oversteer. 
Removing the swaybar(s) almost always allows more wheel movement
(articulation) and tends to keep the force of each tire more evenly
balanced on rough terrain. This allows even open differentials to work
well giving balanced tracion.

  The truck may lean more seem more "sloppy" in corners from one side to
the other. With solid axle trucks there is generally no change in overall
cornering ability but a truck with swaybars will generally "feel" more
secure to the average driver. 

>It's pretty thick. Seems like it'd
>be a good chunk of weight off of the vehicle.  Also appears that the mounts
>for it extend below (remembering with being too lazy to go out and look for
>sure) the pumpkin.  Are they prone to bending or anything?

  Yup, especially if you jack on them or someone hooks a tow cable to one!

Steve Best, Nova Scotia, Canada
4x4 van website:
http://www.glinx.com/users/sbest
Sign up for the 4x4van newslist:
http://www.onelist.com/community/4x4van


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FROM: jackdell 
SUBJECT: Re: Sway Bars
DATE: Thu, 26 Oct 2000 13:30:25 -0400
ORGANIZATION: Monmouth Internet
NEWSGROUPS: rec.autos.4x4

check out http://www.performancesuspension.com they have tons of Sway
Bars in stock along with Poly bushings to replace the factory rubber
bushings. They are "truck guys" and can answer all your questions plus
their runnin a 5% Off Web promo right now so you can save some bucks
too.

jack






FROM: Roger Brown 
SUBJECT: Re: Sway Bars
DATE: Tue, 24 Oct 2000 17:33:38 -0700
ORGANIZATION: SGI
NEWSGROUPS: rec.autos.4x4

Maximum Frog wrote:
> 
> I was wondering what thoughts are on the 4x4's that have front and rear sway
> bars.  As far as I know, most of them are not able to be disconnected unless
> they are some sort of aftermarket thingy.  Do they decrease the
> articulation?  Does it really matter if you have IFS?  What about the rear
> that's still solid axle? Does that get any movement reduction by the bar?
> What's good and bad about removing it?  It's pretty thick. Seems like it'd
> be a good chunk of weight off of the vehicle.  Also appears that the mounts
> for it extend below (remembering with being too lazy to go out and look for
> sure) the pumpkin.  Are they prone to bending or anything?

My 4Runner had the stock front and no rear anti-sway bar, solid axle/leaf
sprung on both ends.  I built some disconnects:

	http://reality.sgi.com/rogerb/4x4/CheapTricks/SwayBar.html

after my first wheeling trip, where I didn't disconnect the front bar (learned
that lesson pretty quick).  I found it made a big difference disconnected,
especially in off-camber situations, say dropping into a ditch at an angle. 
With the bar on, the front wheel that wants to drop into the ditch first is
held up by the bar, causing the vehicle to pitch over to that side.  With the
bar off, the dropping wheel drops and makes contact with the ground and you
get a nice gentle transition.  

Then after one trip where I was too lazy to reconenct the front bar, I found
the handling on the road was much more predictable.  I found the front bar
kept the front end fairly level, but the back end (w/o a bar) wanted to lean. 
This would change the self-steering characteristics of the leaf-sprung axle. 
With the front bar off, both ends of the vehicle behaved the same, I didn't
try the test of rigging up a rear bar.  So, after that I pulled the front bar
all together.  With solid axles, the function of the sway bar is to control
body roll.  Without it the body rolls more.  On IFS, the sway bar helps with
on-road handling a bit, as most IFS systems change wheel camber as the
suspension goes through its range of travel.  So, by limiting the leaning of
the vehicle in turns, it reduces the camber change and keeps the front end
geometry a bit more in line.  

My 4x4 is not a daily driver, but is not trailered either.  Removing the sway
bar(s) and end links and even the brackets on the axle reduce weight, moving
parts, and its one less thing to deal with (airing down, pulling mud flaps,
etc.)

I don't miss my sway bar since I've taken it off, but other folks have had
opposite reactions.  I also know folks who have done a lot of serious wheeling
and have never disconnected their sway bars.






FROM: "Mike Locke" 
SUBJECT: Re: Sway Bars
DATE: Thu, 26 Oct 2000 00:26:58 -0700
ORGANIZATION: http://extra.newsguy.com
NEWSGROUPS: rec.autos.4x4

Roger Brown  wrote in message
news:39F62A62.51B0EE24@pisco.engr.sgi.com...
> Then after one trip where I was too lazy to reconenct the front bar, I
found
> the handling on the road was much more predictable.  I found the front bar
> kept the front end fairly level, but the back end (w/o a bar) wanted to
lean.
> This would change the self-steering characteristics of the leaf-sprung
axle.
> With the front bar off, both ends of the vehicle behaved the same, I
didn't
> try the test of rigging up a rear bar.  So, after that I pulled the front
bar
> all together.  With solid axles, the function of the sway bar is to
control
> body roll.  Without it the body rolls more.  On IFS, the sway bar helps
with
> on-road handling a bit, as most IFS systems change wheel camber as the
> suspension goes through its range of travel.  So, by limiting the leaning
of
> the vehicle in turns, it reduces the camber change and keeps the front end
> geometry a bit more in line.

If you put a high & heavy load on your vehicle, the sway bar is not only
important for reducing lean (a comfort thing for the most part) but also for
improving vehicle stability.  A tall high load (read slide-in truck camper)
will make the vehicle sway back and forth slowly as you drive, making the
vehicle wander side to side.  Shocks are poor at damping slow motions, and
the ride can get pretty hairy.  The sway bar not only reduces the amplitude
of this swaying motion, but also increases the speed, improving the
effectiveness of the shocks at dampening it out.

Some heavy, short wheel base, tall delivery vans (like UPS runs around here)
have an amazing 3" diameter solid steel antisway bar.  Perhaps overkill for
a typical pickup truck or SUV, but hopefully this brings home the idea.

If your vehicle has very stiff springs (how the big rigs control sway, but
usually not a good idea on a 4x4), or the center of gravity is not
dramatically higher than your axles (i.e. stock height and without any added
loading), then your benifit from a antisway bars may be less clear cut.

A question: is the concept that your front antisway should be stiffer than
the rear predicated on the concept that the front has less (or at worst no
more than) the tendency of the rear to sway?  Clearly, the above delivery
van had much stiffer anti sway on the rear than on the front.  OTOH, I've
heard that UPS gets special wavers from the DOT to run the truck they have.

--
S'later, Mike Locke     lockem@scrserv.com








FROM: sbest@TAKEOUTglinx.com (sbest)
SUBJECT: Re: Sway Bars
DATE: Tue, 24 Oct 2000 11:54:54 GMT
ORGANIZATION: Newsfeeds.com http://www.newsfeeds.com 60,000+ UNCENSORED Newsgroups.
NEWSGROUPS: rec.autos.4x4

On Thu, 26 Oct 2000 00:26:58 -0700, "Mike Locke" 
wrote:
>If you put a high & heavy load on your vehicle, the sway bar is not only
>important for reducing lean (a comfort thing for the most part) but also for
>improving vehicle stability.  A tall high load (read slide-in truck camper)
>will make the vehicle sway back and forth slowly as you drive, making the
>vehicle wander side to side.  Shocks are poor at damping slow motions, and
>the ride can get pretty hairy.  The sway bar not only reduces the amplitude
>of this swaying motion, but also increases the speed, improving the
>effectiveness of the shocks at dampening it out.

  Great assessment Mike, but you should make some mention about cornering
balance. Heavy front swaybars on most vehicles are put there to assure
understeer which is a safe and stable condition. Oversteer is where the
tail swings out when cornering near the traction limit. It is an unsafe
and instable condition because it requires driver input to negate its
effects or the vehicle will go out of control. 

  Many of our trucks have heavy front swaybars to balance out the stiff
load carrying springs installed in the rear. This allows comfortably soft
spings to be installed in the front and yet to still have understeer. 

>Some heavy, short wheel base, tall delivery vans (like UPS runs around here)
>have an amazing 3" diameter solid steel antisway bar.  Perhaps overkill for
>a typical pickup truck or SUV, but hopefully this brings home the idea.

  I have not seen the exact truck you mention but I have seen similar
set-ups. The dual wheels on these trucks mean that the rear springs have
to be mounted quite a bit toward the center of the axle. even with their
very stiff rates they offer very little roll stiffness due to their
inboard location. The large rear bar is there to offer sufficient roll
stiffness for the exact reasons you mention up top, and yet just balance
the cornering so that understeer is still maintained.


>If your vehicle has very stiff springs (how the big rigs control sway, but
>usually not a good idea on a 4x4), or the center of gravity is not
>dramatically higher than your axles (i.e. stock height and without any added
>loading), then your benifit from a antisway bars may be less clear cut.


  I agree. With a solid axle vehicle a swaybar has very little benefit, if
you don't mind a little flop of the body back and forth on the corners. 
A swaybar REALLY kills off-road performance on unlevel ground.

>A question: is the concept that your front antisway should be stiffer than
>the rear predicated on the concept that the front has less (or at worst no
>more than) the tendency of the rear to sway?  Clearly, the above delivery
>van had much stiffer anti sway on the rear than on the front.  OTOH, I've
>heard that UPS gets special wavers from the DOT to run the truck they have.

  The stiffer front bar is predicated solely on the need for understeer. 
Swaybars deliver rollstiffness. You definately want more rollstiffness in
the front for cornering balance. Normally stiff loadcarrying springs in
the rear give an abundance of rollstiffness but not if they are placed
close together like on dually axles.


Steve Best, Nova Scotia, Canada
4x4 van website:
http://www.glinx.com/users/sbest
Sign up for the 4x4van newslist:
http://www.onelist.com/community/4x4van


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FROM: "Mike Locke" 
SUBJECT: Re: Sway Bars
DATE: Thu, 2 Nov 2000 22:19:02 -0800
ORGANIZATION: http://extra.newsguy.com
NEWSGROUPS: rec.autos.4x4

Willem-Jan Markerink  wrote in message
news:8tpu92$nlbd5$1@ID-34205.news.dfncis.de...
> In article <39fe1937.1310472@news.glinx.com>,
>    sbest@TAKEOUTglinx.com (sbest) wrote:
> >On Mon, 30 Oct 2000 02:20:17 GMT, "Maximum Frog"
> > wrote:
> >
> >>After reading all these posts, I'm almost afraid to touch the bars on
the
> >>front, but it seems like it may be a good idea to try removing the one
on
> >>the rear.
> >>I remember hearing the ford IFS hasnt really changed much from the first
> >>Twin I Beam setup, and my '66 F-100 has no sway bars front or
back..praps
> >>the Bronco can run the same.  I think I'll be re-re-reading these posts
> and
> >>calling the 4x4 store to wait on hold..see if they'll help me out.
> >> How difficult are the bars to get back on if I decide to leave 'em?  Is
> >>compressing those rubber thingies between the bar and the mounts hard?
> >>
> >>-Max Frog
> >
> >  Not a bad plan, removing the rear bar will normally really improve the
> >off-road articulation while not making the vehicle unsafe on the highway.
>
> Unless you tow heavy trailers....seems a rear ASB (antiswaybar) can result
> in a staggering difference of vehicle stability....
>

Which brings us to the obvious question regarding the stability of antisway
bars:

It was stated that if the front anti-sway is not stiffer than the rear
antisway, then an unstable oversteer problem will result.

Am I correct in assuming that the real statement is

If the front leans more in a turn than the rear then an unstable oversteer
problem will result.
????

Note the critical difference in the statements.  A rear heavy or rear-tall
vehicle may lean more in the rear even if the rear has more antisway
springing.

Most offroad vehicles are rear light, but not all 4x4s are off road vehicles
and it is not uncommon for a 4x4 truck to be both rear heavy and rear-tall.

--
S'later, Mike Locke     lockem@scrserv.com






FROM: sbest@TAKEOUTglinx.com (sbest)
SUBJECT: Re: Sway Bars
DATE: Thu, 02 Nov 2000 18:46:40 GMT
ORGANIZATION: Newsfeeds.com http://www.newsfeeds.com 60,000+ UNCENSORED Newsgroups.
NEWSGROUPS: rec.autos.4x4

On Thu, 2 Nov 2000 22:19:02 -0800, "Mike Locke" 
wrote:
>Which brings us to the obvious question regarding the stability of antisway
>bars:
>It was stated that if the front anti-sway is not stiffer than the rear
>antisway, then an unstable oversteer problem will result.
>
>Am I correct in assuming that the real statement is
>If the front leans more in a turn than the rear then an unstable oversteer
>problem will result.
>????
>
>Note the critical difference in the statements.  A rear heavy or rear-tall
>vehicle may lean more in the rear even if the rear has more antisway
>springing.
>
>Most offroad vehicles are rear light, but not all 4x4s are off road vehicles
>and it is not uncommon for a 4x4 truck to be both rear heavy and rear-tall.


  The reason that swaybars affect oversteer/understeer has little to
nothing to go with chassis lean, but has everything to do with individual
tire loading (weight). 

  You may recall that tracion on a tire increases with its loading, the
pressure that pushes it against the pavement. Unfortunately the traction
does not increase proportionately with the weight (despite what we were
taught in high shcool physics class) but at a decreasing rate. Therefore
if you you double the loading on a tire you only gain half again the
traction (it varies wildly so this is not a valid ratio, just an example).

  So for maximum traction you would want the weight of the vehicle split
evenly between all 4 tires. Drag racing is a bit of an exception because
if you can lift the front of the chassis in a bit of a balancing act you
can put the entire weight of the vehicle PLUS all the force of
acceleration on the rear tires. Diminished returns or not this still adds
up to tons of traction in this particular case.

  Anyway, I wandered off a bit, pre-empting any arguements I guess. 
For maximum traction you would want the weight of the vehicle split evenly
between all 4 tires. This is not totally possible, as the dragracing
example shows, so it is with cornering. The cornering force (which is in
reality another acceleration force) is added to the outside tires and
perhaps some removed from the inside tires. Now if the vehicle is weight
balanced 50/50 F/R and the cornering force applied to the tires evenly
F/R, then it corner neutrally with no disposition for the front or rear to
slide first. 

  What a swaybar does is resist the twist of the body at one axle or the
other. To counter the lean of the body, it needs somewhere to work against
and that is the tire on the outside. A heavy front bar will "channel" the
cornering force to that outside tire (even to the point of lifting the
diagnolly opposite tire), overloading it if you will. Though it may have a
lot more traction, it also has disproportionally more of the cornering
force to deal with and therefore is prone to sliding first when the
traction limit is reached. 

  The reason a rear swaybar makes trailering more comfortable is that it
keeps unwanted movement down and that keeps the ball weight centered
between the rear tires. In trailering you rarely ever approach a skid, if
you did, you might find it likely you would "jack-knife" in this scenerio.



Steve Best, Nova Scotia, Canada
4x4 van website:
http://www.glinx.com/users/sbest
Sign up for the 4x4van newslist:
http://www.onelist.com/community/4x4van


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