shangtsung

Wrong. The rear "axle" is a Torsion Beam. Look up how Torsion Beams work and you will understand that Hotchkins and Progress sway bars really are sway bars.

George

A torsion beam incorporates the functionality of a sway bar. You can even think of it as just a big sway bar with the rear wheels attached.

Aftermarket sway bars just make the spring constant of the torsion beam greater whether they bolt directly to the torsion beam or have their own set of pivots, Heim joints, etc.

Background: 4-wheel independent suspension used to be the ultimate goal, but when it was achieved it was found that cars so equipped rolled badly in corners.

The fix was to incorporate a torsion bar linking the two sides of the suspension, making them work somewhat together, which limited the roll. Most of these bars were installed on the front suspension, although some cars like VW bugs had them on the rear as well. My '68 Chevy pickup had front and rear sway bars stock from the factory!

As auto manufacturers went to FWD with the VW Rabbit/Golf, it was far cheaper to incorporate the functions of suspension and torsion bar into one part, the full-width torsion beam rear axle. Doing this reduced the parts count markedly and made the car much cheaper to produce. For most applications, the torsion beam axle is adequate, with the flexibility of the axle mimicing a true IRS rear end and the stiffness doing a good job of mimicing a sway bar.

George

johncal

Just so you know, the rear axle acts as a sway bar itself since it is directly attached to the frame as well. Adding the sway bar just stiffens it further. The way it is designed, it functions as a semi-independant suspension. Since it flexes, it is unlike a rigid axle rear end, but acts like an independant suspension with a sway bar built in to the design.

I would NOT recommend adding an additional rear sway bar unless you add additional stiffening to the front end as well. Otherwise you will increase the overall oversteer, and could create a massive amount of trailing throttle oversteer which could easily spin the car out if you are pushing to the limit through a turn and take your foot off the gas quickly.

The car is actually pretty well balanced with just a touch of understeer. Always increase stiffness at both ends and equally.

Johncal

johncal

BTW, George knows the deal.

Johncal

magicmanjk808

did you seriously quote a post 11 months old to tell someone he's wrong while there is already plenty of information in this thread.

i'm sorry, but i have to disagree here. i added the progress rear sway, and the handling became more neutral. while adding a front sway would have increased stiffness, it would also increase understeer. once i switched the progress to a whiteline, it was wwonderful. handling was great, and if i wasn't a suspension guy, i would've left it at that. it is perfect for the everyday spirited driver. unless you keep adding stiffening to the rear, you don't need to change out the front sway, just upgrade the bushings. you can, but it won't give you the neutral handling you should be looking for.

TXboxdriver

why is body roll such a grave concearn
why do you want to limit your stroke this way
if your springrates and shock vavling are set right
you should not need a sway bar
remember that weight transfer is important
and limiting suspension travel can be bad

swaybars (IMHO) are a band aid for improper spring/ride height tuning

BrianxB

I disagree with you. Many people who are into serious handling and autocross run no front bar and run a rear sway alone. The Hotchkis setup I had on my 02 celica was like 40% stiffer in front and twice that in the rear over stock. That car would outhandle almost anything.
It all varies from car to car of course, but most people who know how to drive know that a little oversteer is what you want. Youd never want understeer.