joey bagadonuts

Funny, Mark.

Chance, I'm not sure that's exactly right. While you may see guys going with 400/600 springs which would align pretty well with our cars' 40/60 weight bias, I don't think many folks with 800-lb fronts are running 1,200-lb rears to achieve the same ratio. I think what you typically see is a difference of 200 lbs or less between front and rear.

chancecasey

Yeah, that's right - they appeard to be more proportional in the lower ranges but in actuality I guess it's of a static difference, as illustrated when looking at what most people run in the higher rates.

garrett376

I think it's more importantly about the ratio... I've found for a C4 using neutral sway bars (stock sizes) a slight tendency toward oversteer can be achieved using a 1:1.5 ratio; thus my 525/800, and 300/450 rates.

Sounds like C2's most popularly go with a 1:1.1 - 1:1.3?

joey bagadonuts

Garrett, That sounds about right. When I went from my C4 to a C2, I transplanted everything--RS coilvers, sways, wheels. tires--and it was just a bit loose. A quick sway bar adjustment and I was back in business.

If I'm not mistaken, both of these cars also used a massive 24mm front sway bar along with the relatively small 18mm rear. I won't presume to know what the Factory was thinking but this bar combination would certainly be the ticket to tame a tail happy car. Why not use similar spring rates front and rear, instead?

Fast4525

Thanks for all the feedback so far

Maybe we could start a poll of 964 C2 track/race cars to see what springs rates are working for various people? Of course sway bar selection would need to be part of this.

Are the ERP camber plates the best available?

Once we are past the spring/shock questions, which are the most critical bushings to upgrade? Is there something between stock mushy rubber and *****-to-the-wall monoballs? Maybe like a Sport/M030 bushing, urethane or delrin?

Marc Shaw

Powerflex, based in the UK, make polyurethane bushings.

Marc

dougn

it's crazy to me....the fact that spring rates as well as damping numbers vary all over the place. i think i'm zeroing in on a really nice feeling/handling street suspension. right now it's at 200/265 spring rates with custom valved bilsteins. i'm soon going to switch to 175 fronts and porsche N rated tires. i think the N rated tires are softer in the front hence the lower load rating. it makes sense considering the front is so much lighter than the rear.

it turns out i'm ending up with the equivelent of porsche M030 suspension ...albeit a bit lower

Fast4525

So much of this suspension tuning is based on feel and not lap times. Do what you think is best

Who did your custom valved Bilsteins and what type of springs are you using?

dougn

bilstein in san diego will revalve. i use hypercoil springs with custom spring perches.

regarding lap times and track use. i believe the street and track are so much different you have to choose one and set up for it.

i think when people say their high spring rate car is ok for street use they don't mean it handles well over a rolling bumpy road during a spirited drive. the spring rates are way too high and there's about .5 inches of suspension travel....

Fast4525

Very interesting

Has anyone tried using the same rates F & R on a 964 or even a reverse (800F/650R)?

Geoffrey, for a 2900lb street/track car do you think that 700F/800R, with the correct dampers, would work well?

TR6

The problem is that you stated the requirement for a 50/50 street/track car. Everyone has a different tolerance for how much they are willing to have their fillings jarred out on the street. Personally, I'm running the Bilstein/H&R red combo and I don't think I'd want anything too much stiffer for street use (especially for a 5 hour trip). It seems to do fine (at my level) at the track for DE's. I also have RUF aftermarket sway bars and a few other tweaks. Certainly, my setup would not serve well as a race car though. You have to decide what your real tolerance is for harsh, rough street driving. And as someone else pointed out, an overly stiff suspension on the street actually handles worse in typical street conditions. I guess its the old saying that a compromise street/track car does neither very well. Not sure I completely agree with that, as I think my compromise set up does fairly well, again, at my level of track driving (DE only).

Larry Herman

I would recommend that you strongly consider adjustable shocks. They can make the single-most difference in the way your car handles on the track, and the way it feels on the street. Softening them for the street will remove all of the minute impacts that you normally associate with stiff springs, and can make your car reasonably confortable.

springer3

I don't track my car, so excuse any ignorance. Won't the optimal spring and damper rate depend on how smooth the track is?

My experience on street driving is that my E-class Mercedes cornered much faster on a washboarded curve. This was a back road on my daily commute, and I had plenty of opportunity to run both cars at the same speed. The 964 would get bounced off track, but the 300 E handled the washboarding just fine. Both cars have Bilsteins with stock springs.

Fast4525

Fair enough. I am to the point where I know that I can live with spring rates in the 400-800lb range so now I just need to decide on some good rates to try.

Perhaps I should start a new thread to discuss spring rates, motion ratios and F to R rate splits?

My car is ~2900lbs and has RS adj. bars. What do you guys think of 700F/800R with the correct dampers?

This isn't a race car but it is probably 10% heavier than a race car so the rates might need to be a little higher.

joey bagadonuts

Excellent observation and right on the money!

Rob- What car did you end up with? The Chicago one we discussed offline wouldn't need a thing. If that's the car you got, I'd just enjoy it for a while (around town and at the track) before making changes.