Sway Bar 01-03

[Cal Cruzer]

quote:Originally posted by Dragula

Stiffening the rear bar will decrease the understeer. Adding too much rear bar would cause an oversteer condition.

Stiffening the rear bar will make it track better and make it more difficult to break the rear loose, causing the front to push more (understeer) if it is not stiffened too.

[Dragula]

Adding too much rear bar will cause the rear to break loose. It decreases body roll which decreases the weight transfer to the outside rear tire exiting a turn.

My Impala SS suspension has a stiffer front bar than stock, and the stiffest rear bar available. The rear bar was modified after the front bar, and it did increase the tendency to oversteer when installed. A freind of mine had the same setup and was autocrossing and road racing his Impala SS in the SCCA. He was actually ranked #1 in his class regionally in 2003(I think that was the year). When he got serious, he added a roll bar to the car which stiffened up the chassis. He had to downgrade the rear bar to the stock unit to decrease the oversteer condition that resulted.

The manufacturer builds in understeer because the average driver doesn't instictively know how to react to oversteer. I know we want to get our cars as neutral as possible. Adding a rear sway bar of appropriate design and torsional strength will decrease understeer. Too much rear bar in relation to the front will cause oversteer.

I have only heard this debated once before, and it was on this forum. I'm pretty confident that what I've stated is the truth. Buy a front/rear anti-roll bar set from a respected manufacturer, and you will probably have a well tested setup regardless.

[Paw]

anybody on the forum have a 02 swaybar install on their 03 car? That way I still have the OEM sway bar. I think the touring is the same as the swaybar for the 03. Accordding to the dealer their is only one available for the line

[1ptturbo]

You have to remember this is a front wheel drive car and anything that applies to a rear wheel drive car you can throw out the window. I can not say the last time I saw a front driver lose the back end. It will lift the rear tire before it will break loose, scary.

The PT will benefit from the addition of a rear bar, period. I would recommend buying an aftermarket set that is larger than stock. The single and most effective suspension mod that I made was the addition of an eibach bar set. I can say this with confindence as I had also installed eibach springs and koni shocks. I have since returned the PT to stock, except for the bars, and it handles as good as when it had the eibach springs. I would have gone larger but at the time I did not know of a larger set and I got a good deal on the eibachs. Personally I think the eibach and just about every other lowering spring is junk, they just do not offer a lowering spring with a higher spring rate. Anyone know of a company that makes a performance lowering spring for the PT?

[Dragula]

I agree that front wheel drive and rear wheel drive vehicles react differently. I still don't believe that you'd induce understeer by increasing the rear swaybar. If so I'd honestly like to see some data to back that up. I didn't mean to start a debate, but what Cal Cruzer said is totally opposite to what I've had experience with. Maybe he has more experience with front wheel drive vehicles.

It's a lot easier to keep the rear wheels planted when you're not putting power to them. However, there is less weight in the rear of a front wheel drive vehicle so that's another issue.

Also, if you stiffen the rear suspension wouldn't you actually increase the chance of lifting the inside rear wheel in a turn?

Anti-roll bars are the best suspension upgrade as far as performance is concerned. I installed the Eibachs for appearance sake, and Tokico HP shocks/struts to compensate for them. It definitely rode better with the stock setup. Unfortunateky I've yet to add a set of swaybars to the GT (concentrating on the other car).

[MichaelDay]

Here are some descriptions of the affect of large front or rear sway bars on a front wheel drive car. Note that some of the information in the first link assumes that the car has VERY tight springs with reduced travel.
http://www.stealthtdi.com/SwayBars.html
http://www.grmotorsports.com/swaybars.html
http://www.domestictunerz.com/lofive...hp?t13147.html

In all cases there is agreement that a larger rear bar will reduce understeer on a front wheel drive car. Note that lowering the rear of the car more than the front will induce MORE understeer.

[MichaelDay]

An additional factor in aggressive use of sway bars to control body roll is the entire rear end gets light at very high speeds which decreases understeer / increases oversteer.

You may recall that 3BarBoost indicated that the PT acted like a giant wing at the upper end of its speed range lifting the rear of the car. That lift will reduce traction and can change the PT dramatically reducing understeer or even changing it to oversteer.

[MYREDPT]

I have an early '03 GT with the rear sway listed on the window sticker. I added a Mopar High Performance Rear Sway bar since I had it from my old '01 Limited and I really like the difference. I am not worried about extreme high speed handling since I will not be taking my PT on Pocono or Watkins Glenn. I am no engineer or professional driver but I do know what a big rear bar does on my race rabbits and I like it! Did somebody mention rear wheel lift?



44 events, 43 podium finishes. 2002, 2003, 2004 NNJR Class Champions, 2002,2003,2004 NASA Northeast Class & Points Champions, 2003& 2004 Waterfest Class Champions

[Dragula]

That's great! My buddy Marcelo races older VW's. He would love those pics. I'm always trying to lift a wheel drag racing in my Impala SS, but that's not the one!

[MYREDPT]

Thanks Dragula, tell your friend to go to www.abellaracing.com for loads of VW and autocrossing pictures.