mcipseric

This is what I did. the car was lower than RS ride height for a bit when I was time trialing. I raised to RS height now that the car only does street/AX.

race911

We were channeling each other from across the country? (Or maybe some texts leaked off from my racing buddy who's in her MBA program over in Ann Arbor......)

In any case, this stuff was fresh in my (hurting) head from that data acquisition seminar. Amazing what you can derive from some shock pots and other hardware that only a few years ago was reserved for the highest levels of pro racing.

Funniest thing is some Spec 911 bump steer data that is contrary to what "conventional wisdom" has been preaching for, oh, FORTY years. I was not aware that my friend's car, one of the Spec 911 front runners, was so massaged.

Steve Weiner-Rennsport Systems

Yessir,...them's are true words.

Two of the biggest differences between an "OK" handling car and a REAL good one are shock valving & time spent on bump (roll) steer optimization (front & rear).

Pays HUGE dividends, as you know,...

Magdaddy

I have what I'll classify as mild bump steer, don't know if RS pieces are worth the investment for purely street driving. But...my vote for first really cool thread of the new year to responses here. Now my brain hurts, I gotta go get another drink. Thanks all...

race911

I'll let Steve speak to the particulars, if he cares to as I've never bothered to measure bump on a 993, but I'll guess raising the car even 1/2" will make a marked improvement.

Last month I drove a 964 someone wanted to buy, and it was about halfway between my 4S and the properly set up yellow car. I think there was an inherent toe issue in there as well, but the car was pretty much undriveable. Of course the owner took issue, as the car was set up by "the best race shop" in our area.....

Essexmetal

I have bumped a lot of cars, life is so easy with an A arm suspension with a coil over. Since it is a pain to do a 993 I prefer to suffer with bump steer. :-) I have done mine by securing the body to the hoist deck and forcing the hub from full droop through ride height through full compression. Standard bump steer tool, hinged plate with two dial indicators, hub mounted datum plate. Just a pain doing it with the suspension moving against the springs. That makes that A arm set up great, you just unhook the coilover and everything moves up and down so easily by hand.

DanL993

THANK YOU. You guys finally expalined why my car tries to go left for just a second after a bump...usually a bridge/road transition but happens other times too. Still occurs after a rigorous alignment (although it seems reduced) and so it mystified me.

Now I gotta decide what to do about it...if anything. Magdaddy and I do street stuff and it may not be worth the candle.

Thanks again. Great thread.

Bill Verburg

When using Porsche parts it's best to stick w/ Porsche specs


only if you use these aftermarket tie rod ends will it be worth bumping the suspension
top aftermarket tie rod end, bottom RS/GT2 tie rod end

race911

^^^ Note that intersection between the ROW M030 at min height spec, and the RS at max height spec.

Again, I've not bothered to do a 993 (and the RSA was raced in stock class, so whatever bump steer there was I just dealt with it in the overall goal of getting the car as fast as I could), but I wonder how the data compares.

Just to throw it out there, I set the 4S at ~135mm when I put the PSS9 kit on about 3 years ago. Then I raised it to ~150 when it was going out for serious snow duty a couple of years ago. Difference? Maybe. But the roads are too bad in CA to really compare from seat-of-pants.

LITTLE TANKER

Fantastic boys!

That's a lot of info, most of it too advanced for me at this point. I think I will make the leap to the PSS10's soon and rise my set up as stated before. I don't track the car and want a comfortable drive for now anyways...........who knows in the future.

race911

Got a PM, so I thought I'd circle back and clarify my posts 20 and 24, mentioning that raising a car 1/2" would likely lead to a noticeable difference, yet I couldn't tell on my own car.

Meant that you'd notice if you have a car with stock components set well down in Bill's "Red Zone" chart, and brought it back up to maybe the lowest end of ROW M030 specs.

LITTLE TANKER

Ahhhhhhhh, I see Ken................... Thanks for clearing that up! I understand. looks like i have a couple ways of getting the car where I want it to be.

Thanks for all the help!

Vince

TheOtherEric

Like was said above, at RS +10mm ride height you'll get some serious bump steer. This can be rather irritating -- the steering wheel is constantly jerking back & forth in your hands over every expansion joint or bump. Very annoying to me. I recently raised my car about 0.5" and it disappeared. A must for street use.

LITTLE TANKER

A 0.5" lift on my car would probably put my car right where I like it astedacly speaking........

Thx pal!

il pirata

So if I stick to RS factory specs can I assume on my 1996 C4S that adding RS uprights/tie-rods will resolve most of the bump steer and not require camber plates?

Also I am currently using PSS 10's? Any other parts/gotchas when connecting to the RS uprights?