T&T Racing

I am starting this thread because I was reviewing a Rennlist Posting on 944 Front Springs started in 06.07.2005 by OP Bill L. Seifert. The conclusion from the 3 pages of threads that there was no consensus.

I have a 1983 Porsche 944 setup for SP2 but the car is raced in SVRA. The bottom line is the car has too much understeer and specifically to Lime Rock is where the testing was done.

The original suspension setup was front spring 450#/in, Target front sway bar, Koni double adjustable shocks, and reinforced gusset steel lower control arms, and polyurethane suspension bushings, Ground Control camber/caster mounting plates; and the rear has 31 mm hollow tube torsion bar, Koni double adjustable shocks, 951 trailing arms,Tarett rear sway bar, bronze bushings and rigid mounts for the torsion bar housing and attachments. The car had 7x15 square R6 tires/wheels. The front camber was -3.0, castor +3, and toe was 0. Rear was standard setup. The car had too much understeer.

I determined the Target sway bars had only one adjustment setting where 100% of the rotation force was perpendicular to the front or rear lower control arm. Any other setting had both a perpendicular and horizontal force, not good.

Fast forward to today. The car was test driven at Lime Rock by a professional race driver who has 1000's of laps at Lime Rock. The setup now for the front is 500 #/in springs, ANZE double bleed shocks, HighStrung44 lower control arms with OEM ball joints, MO30 26.8 mm sway bar, delrin bushings for front sway bar; and the rear is the existing 31 mm hollow torsion bar, 19mm Porsche 3 hole adjustable rear sway bar with delrin bushing in the mounting brackets and spherical bearing drop links.
Corner balanced as before to 50%, front suspension settings are camber -3.5, caster +5.0, toe out total 1/16 in and rear sway bar full stiff with the standard other settings. Tires are 8"×15 all square R7. Front tire hot pressure was 36 psig and rear tire hot pressure was 35 psig. The car as tested was understeering in right handers, especially turn 1 and was better in the the left hander. The car understeers at corner entry and specifically turn 1 is trail braking to at least the first apex

My pathforword is to determine if there is binding in the front suspension +/- 2 inch around normal ride height, and then in full droop, determine camber change from normal ride height as previously described for binding, and determine bump steer. Also determining front wheel scrub radius as the tire width increased by 1" but do not know the offset change for the 8" wheel vs the 7" wheel. his data might explain some of the anomalies but there could be other unintended consequences.

What are you and other PCA SP2 and SP3 racers running for front and rear suspension components and setups; and why and where, and are they different for different tracks?

I want to have fun, currently like the challenge but it has to resolved 🔜🔄 so it can be a 😃

will968

Your setup sounds fine, but I can think of two things to check:

• What is your diff setting, specifically the preload?
• How much rake do you have in the car? Is it level or rear bias? Get it on a level surface put a spirit level on the door sill.

T&T Racing

Preload is bias towards braking.

The car has small amount of rake

will968

What is the static measurement: when one wheel is on the ground and other in the air - in neutral. How much force does it take to turn the wheel? If it's a lot, you can have trouble getting the car to the apex. Although it's easy to overcome in T1 at LRP with trail braking and line adjustment.

Most 944 drivers aim for level. You can lower the front to increase grip at the expense of rear traction.

Also, who did your corner balance and alignment? Not all shops are equal ....