So I'm finalizing my track suspension set up on my 987.2 CS. I decided to go with Cayman R ride height (-20mm compared to standard suspension) and stock tires. However, I am now seeing that my track tires (hankook c51) are approx 20mm shorter in diameter (translated to -10mm in ride height) which would put my car at -30mm.

I have 2 sets of wheels, 1 set with Hankook C51 and the other with Extreme contact sports (oem heights) which I would like to use interchangeably at the track.

I'm thinking i will just lower the car 10mm from standard which when fitted with the Hankooks will put me at -20mm which is Cayman R height and -10mm when running the Conti which is PASM spec.

Does this make sense? I picked Cayman R ride height to begin with since its a factory specification but the car is track only at this point. It has PSS9's and full monoball suspension. -3F/-2.5R camber? Thoughts?

 

Unless Im having a brain fade I would assume it doesn't matter that the car OVERALL is lowered 30mm when using the Hankooks because you only really lowered the suspension 20mm thus retaining the Cayman R ride height in regards to suspension geometry and available shock stroke etc. I don't know about 987.2 but you may need aftermarket rear toe links when lowering the car?

 

I have the rear toe links. I do think you have to take into account the effect of the tires on the ride height because there are tires where the height differential between front and rear is quite different from stock.

For example, the stock tires are 20 mm smaller in diameter at the front than they are in the rear. All else equal, this gives the car positive rake.

There are other tire options where the front tire is the same or slightly taller than the the rear. Fitting these tires would decrease or eliminate the rake and the weight distribution.

You would end up correcting for this when doing a corner balance whether you intended to or not.

 

I set ride height to match OEM rake with my primary tire diameters. I would not change it when using the secondary set of tires. Everytime you change ride height you are also changing toe. If just a track car, why set ride height to match a Cayman R street car. On my GT4 I run about 10 mm lower than OEM.

 

Hi Bill,

Thanks for your input. I guess in a way my question is really, what ride height should I go for. As you may be able to tell I'm doing this DIY, so I chose Cayman R ride height as sort of a known, tested spec.

The difference between base and cayman R is -20mm. Throw those C51's on and now it's -30mm.

That would be at the lower extreme of the tolerance for the cayman R spec so I'm assuming that should still be acceptable and safe.

 

I run about 12mm lower than the cayman R in the front and about 20mm lower in the rear. Plenty of clearance on the street, still easy to align, and a little less rake than the R.

 

second this. On the track the rear can come down A bit further than the front. My track-only car is about -20mm/-30mm from R specs at the moment, as a reference.

or another way to think about it, At least bring them down proportionately, rather than by a fixed amount per end. For reference Stock CR is 106mm front and 133mm rear +/- 10mm, I believe.