InTheAir

Hear me out, guys.

With my Bilstein HD shocks, M030 springs, and M030 sways coming, I wanted to get a better idea of how to set up my car, so I'm hoping so many of the experts around here could lend some advice.

A little background--

The car:

• 1996 Carrera 4 Cabriolet;
• stock cup wheels;
• Dunlop SP Sport 8000 (F: 205/50ZR17; R: 255/40ZR17) (switch to S02A's in a year or so)
• Bilstein HD
• M030 Springs
• M030 Sways
• KLA Strut Brace (also adding)

The Use:

• No Track
• Aggresive Street Driving

Intended Ride Height: I'm unsure which to choose here. From Robin's site (www.p-car.com) I've learned these values measured at the points noted in the attached figure:

USA Std: Front 174mm, Rear 157mm
USA Sport: Front 174mm, Rear 157mm
ROW Std: Front 154mm, Rear 147mm
ROW Sport: Front 144mm, Rear 127mm
Carrera S / 4S: Same as Sport for USA / ROW as appropriate
Carrera RS: Front 124mm, Rear 107mm
Measurements are plus/minus 10mm

I suspect I want either ROW standard or ROW Sport height, but I'm unsure. I don't want it to be too low, but I want a fender height ~around~ 25" (I think). Can you give me some input here??

Corner Weighting: I'm not sure I need corner weighting for my intended use--street driving in a cab. The local, well known shop charges by the hour ($110/hr) and estimates it to take about 2 hours to corner weight. Is this an expense I should undertake? Is this something I will feel in a cab? If the ride height is set, is the corner weight "close enough" for a street driven cab? I want the car to handle it's best, but I also don't want to spend needlessly.

Alignment Specs: Again given my intended use, I would like a nice street alignment--one that showcases the new suspension, but doesn't eat up the tires too fast.

As I understand it, I want to probably split the difference between the RoW settings and the RS settings, which are listed here. If that is the case, I assume I want:

Front Axle -
Toe Unpressed (Total) +5' +/- 5'

Toe Different Angle with 20° Lock -1°36'±30'

Camber (with straight alignment of wheels) -10±10'
Max. Difference left to right 10'

Caster 5°20' + 15'
Max. Difference left to right -30'+15'

Rear Axle -
Toe Per Wheel +10' +/- 5'

Camber -1°15'±12'
Max. Difference left to right 10'

Kinematic Toe-in Adjustment 1.5 SU
(Sterring Angle 2 to Steering Angle 5)

How does this look? I'd like to just hand this to my alignment guy.

chris walrod

10mm under ROW height is a great compromise between bottoming the front at steep inclines and having it look too high. Low looks awesome on these cars, but not the most fun to drive.

Cambers and toes by the book for a street car. Take some front and rear toe out of the car for track work. Ride height pretty much dictates max negative camber that one can get out of these cars. At ROW height, I cannot get more than 1.75 deg rear and 1.5 deg front. This is a decent mix for my street and track duty. Although I havent had much of either this (last) year..

chris walrod

Forgot to add a big 'thank you' for working the pogostick group buy! Even though I cannot participate, a big ole thanks comes from me

InTheAir

Chris, thanks for the comment. The Suspension GB was my second GB--call me a glutten for punishment. So, just to be clear, your suggestion would be:

ROW Std: Front 154mm, Rear 147mm
MINUS 10mm
Suggested Height: Front 144mm, Rear 137

So you are suggesting to simply follow the "ROW:Sport and lowered" settings from this chart: http://p-car.com/susfaq/alignment.html

???

I appreciate the help.

Edward

Hi Jeff,

For a good street-performer w/o track, I'd try to get about -1 to -1.2 degree camber up front, and around -1.3 to 1.5 in the rear. This should reduce your understeer and get you more cornering bite w/o eating up your tires (as a data point, I've got -1.7 in the back and still have no probs with treadwear).

Cornerbalancing is your choice. I'd save the dough if you're not intending track use. Just try and get the corner heights consistent L-R, and measure from a chassis point which is far far more reliable than measuring at the fenderwell. If you arrive at good measurements, and your rake is right, you should have a decent cornerbalance for the street. I'll leave toe and kinematic to others

Edward

Joe S.

My C4 cab with PSS9’s & TRG bars, F: 225/40ZR18; R: 285/30ZR18 has the following ride height:

Front 122mm / Rear 112mm which brings the fender height to about 25in.

I really haven’t had any issues with bottoming out. I’m just pretty careful with driveways etc.

Hope the helps.

kkim

Jeff,

I'd shoot for ROW sport height and definitely get it corner balanced. I envy you guys that have the means to have the car set up as it was intended to be. Don't scrimp on corner balancing at this point and enjoy the car to it's fullest with regards to how it was designed.

I ran camber at 1.2f/1.5r. Toe at 1/16" total at both F & R. Max out caster in the front. Use a shop that can set kinematic toe accurately using the correct equipment.

Good luck... you will love the transformation with the new suspension and alignment.


Joe S. - Love your new avatar!!

Joe S.

Thanks Kelly!

TheOtherEric

If I weren't doing track events, I would definitely be using RS spec alignment. I wouldn't go more aggressive with camber unless you really enjoy buying new tires. Heck I tracked my 993 with street alignment and R-comps for an entire season and had very respectable lap times.