Quote:
Originally Posted by Thunderguts
I'm planning the following suspension mods and I'm wondering if the 28mm front sway bar might actually downgrade handling.
My 128 already has the sport suspension with rear sway bar. I'm running a square setup with 225s on all corners. I'm planning to add BMW Performance springs (T1 all around) with Bilstein B8s and M3 control arms (definitely front, maybe rear). I'm hoping to get around 1.5° negative camber in the front and whatever I can get in the rear. I'm thinking the 28 mm Performance sway bar would reintroduce understeer, no?
Obviously the proper answer is to wait until I have the suspension set up, but sway bars are cheap and I could do it now while waiting to do the rest. I just don't want to bother if it's likely to make me understeer.
Would the increased negative camber in the front offset the larger sway bar and thus improve my overall grip while keeping the handling neutral?
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I would add Dinan camber plates up front, so that you can get at least 2° negative camber.
Larger sway bars up front can actually reduce understeer on cars with MacPherson struts up front. From this thread:
https://www.1addicts.com/forums/showthread.php?t=677455
"The reason why BMW front suspension typically employs a thicker front anti-roll bar is because of the MacPherson strut design. Unlike double wishbone type suspension, the MacPherson strut has an unfavorable camber curve, in that the camber does not increase linearly as the suspension is compressed. So as the car takes a corner and sets, the outside suspension is going to compress past the roll center and will go from a favorable increase in negative camber to start to lose the negative camber. When that happens the front end will lose grip rapidly. One of the solutions to alleviate this problem, is to deploy thicker front anti-roll bars to prevent the outside suspension component from compressing PAST the roll center and start to lose camber. It's a way to artificially increase spring rate to one side of the suspension without giving up straight line ride comfort. You'll find that most balanced chassis with double a-arm or double wishbone suspension front and rear will likely have very similar anti-roll bars front and back. A great example is the 1991 Acura NSX, the front and the rear anti-roll bars are within a MM in diameter and the NSX-S (JDM versions) actually has thicker rear anti-roll bars. In 1993 they increased the front swaybars to remove grip up front and promote "understeer" since the early NSXes were deemed too tail happy (i.e. NEUTRAL) for 99.95% of your average drivers."