Hey. Title pretty much says it all, but I will give some background.

I have a wrx, I know I know, and our cars are greatly enhanced for autox purposes by adding a huge 24-27mm front sway bar. This tends to go against convential suspension tuning thought.

What I am wondering is if the effects of the front sway bar are tied to the type of suspension (mcpherson) we have or if it is due to the AWD??

How does a larger front bar effect the Evo?

Tony
TiC

 

bump

 

Less body roll and prob huge understeering prob unless you have a larger sway bar in the rear also. I believe the only company that make a front sway bar for evo is Cusco and they also sell mounting brackets for the front to make your stock sway bar adjustable. I have those brackets and I think they are sufficent, prob not a good idea to get a larger bar.

 

Front sway bar:

Advantage: Faster turn in
Disadvantage: Understeer potential

Counteract with: Rear sway bar tighter than the front with regard to %.

 

The EVO responds to swaybars in a totally different manner than the WRX.

Like EVOTexas said, the turn-in is slightly faster, but the understeer is horrible once past the apex.

It's not so much the interaction with AWD or the struts (the WRX has the same basic components) it is more along the suspension design and the placement of the steering rack. On a subaru, the steering rack is in front of the plane of the axle. So when you get body roll, the outside tire toes out, the inside toes in, in an opposite direction to turn. (I.E. If your turning left, the tire moves towards right when the body rolls over)

On the EVO, the steering rack in behind the plane of the front axle, so when the body transitions into the corner, the outside tire toes in, and the inside tire toes out, in effect, steering the car into the corner more.

It's been my observation from my own testing (and results) that the EVO responds better to upping the spring rates over changing swaybar settings.

why?

I did a popular mod on the EVO, which is to drill a second hole in the stock swaybar. It offers an aproximate 40% increase in stiffness when switching to the "stiff" setting. I did this mod for the '04 Atwater national tour. On Saturday I ran with the stiffer bar, on Sunday I ran with the stock setting.

I ran in STU for that event, the car was basically stock, with falkin azenis sports, front swaybar mod, and shifter bushings.

stiff swaybar
Saturday's results 65.505, 65.473, 71.936(3) http://www.scca.com/_Filelibrary/Fil...ertour-sat.pdf

stock swaybar
Sunday's results 58.404, 57.030, 59.819 http://www.scca.com/_Filelibrary/Fil...ertour-sun.pdf

As you can see, I was faster on the stock swaybar on the same course with roughly the same weather conditions (smoggy and hot hot hot)

 

A larger front swaybar on a WRX helps control camber curve problems inherent in a mcpherson set up.

27mm is pretty large though...at that point you are probably going backwards. It's important to match a big rear bar with a big front bar....BALANCE BALANCE BALANCE.



944 turbo guy

Myles Williams
www.racecompengineering.com

sales@racecompengineering.com

410-730-RACE
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410-707-0108 mobile.

 

What do you have for a rear sway bar? I have done the front bar mod also but I also have a Hotchkis rear bar on full stiff. It's a schweet little schetup!

 

I am running the Cusco 25mm bar up front along with their adjustable brackets set to 116%. The rest of the suspension is stock. The reason I went this route was simple, that is about all I could do suspension-wise (besides changing shocks) and stay in A Stock for autocross. In short, the car is better in transitions, but seems to give up a little in sweepers. If the rules allowed for a more balanced approach, I would have gone that route, but they are what they are.

BTW, installing a front bar on the Evo is not a trivial task...

JW

 

I have the same setup and I concur

Like Myles said, balence is everything.

yes it is. That's why I drilled holes in my stock unit. There is a thread in the "how to" section that has decent instructions on how to do this.

 

24mm or 25mm front on evo right?, get something similar in the rear.

balance is indeed the key.

rear is i think 23mm or smaller on evo.