marton

Hi Alex,

about "I have been given some settings, which supposedly are Porsche Motorsport's own for the Nurburgring."

I find that ride height difficult to believe unless they are somehow measuring in a different way from the rest of us. Who gave you these settings? Do you trust tehm?

Marton

SharkSkin

Tire pressure seems reasonable, depending on the tires. I run 30F/28R on regular 17" cups. What matters is not the actual number, but that the pressure used provides an even contact patch. With my "too low" pressure the tires do not roll excessively and pyrometer measurements after ~10+ miles at high speed indicate even temps across the tread. The actual cold psi must be determined for each tire/wheel/car combo. There is no one "right" pressure.

Cheburator

Got the car aligned :

Front camber -1.5
Front toe 0.5
Front caster 4.5

Rear Camber 1.35
Rear Toe 0.5

Ride Height - 115mm at the front and rear.

It works a treat! Hopefully you will see it at the Ring this week!

Dennis K

This is a letter from Porsche to Kim Crumb several years ago:





Here are a couple letters from Porsche to Kim Crumb. The first one written in 1994 describes the settings and option packages for 928 Cup cars. The second one written in 1998 describes a more heavily modified racer that saw action at the Nurburgring & Daytona. There was also a magazine article about the later car but I've lost it. Warning, these are executable files (viewer program included w/ letter) and some virus software may not be happy with that. As far as I know, these files are safe, as I've had them on my systems for several years now w/o any probs.

1994 Letter about 928 Cup cars

1998 Letter about Daytona/Nurburgring race car

The 1994 letter describes the 90 mm ride height for the Cup car. No mention is made of the Nurburgring.

The 1998 letter has various suspension settings for the Nurburgring & Daytona but no mention of ride height.

Hope this helps.

Dennis K

What kind of tires?

Cheburator

Cheap!

No, seriously - I have Bridgestone Potenza S02 265/35/18 and Falken grB FK452 235/40/18 at the front. Both sets are brand new... This is the car's first outing, so I wanted something which is middle of the road and thus open to manipulation either way. It seems that I have managed to get pretty close to the N-ring settings instinctively anyway. Thanks for all the suggestions!!!

Rehan

Spring rate 1340/800 lbs/inch for the ring and or 2000/1140 lbs/inch for daytona, that is stiff

I thought that my 800/525 was stiff, but that is kind of soft when compared to these figures.

Jim bailey - 928 International

Spring rates that stiff might help explain how they can get away with running very low ride height because it simply is not going to compress much !

Cheburator

I seriously doubt that these rates would have worked in the mid 1990s. The Ring used to be a very bumpy place back then. I run a VW Golf with 855kg/cm Fronts and 550kg/cm rears and that one is too hard to control unless the conditions are bone dry even nowdays... I think 800/525 set at 2/3 fronts and 1/2 rear (bump and rebound) would be ideal, but then that's me... Will keep you updated...

drnick

the rates i see are 350/200 for daytona and 235/140 for the nurburgring. the nurburgring rates seem broadly similar to 550lb front and 350 lb rear, are they suggesting over 3 degrees of camber? also is that 30 minute of toe in at the rear?

FlyingDog

They're only running 13mm lower than minimum stock in the front and 30mm lower in the rear.

Jim bailey - 928 International

I believe the stock front height is 190 mm - 20 mm , rear is 173 mm - 10 mm. So setting it up at 90 mm would have the front some 80-100 mm lower than stock which in inches for the metric challenged is 3 to 4 inches LOWER. Stock GROUND CLEARANCE is 120 mm or 4.72 Inches which is why I asked where they were measuring ! Clearly taking 4 inches away from 4.72 inches of ground clearance is simply NOT going to work BUT if they meant reduce GROUND clearance from 120 mm to 90 mm then the measurement to the "contact surface" would be changed from 190mm to 160 mm front and 173 to 143 rear.

FlyingDog

Jim, if you look at the WSM page in the link, front is 123+/-10, rear is 120-20 (78) or 130-10 (for 79-80). I think they're using the WSM method of measurement (bottom of suspension up to hub), not what most people use (bottom of suspension down to ground. Looking at the diagram again... I think they've raised the car, not lowered.

Jim bailey - 928 International

The later spec books use the numbers and "contact surfaces" I mentioned and I seriously doubt Porsche would have raised the car for anything other than Paris Dakar ...

Rehan

Download the second document and look under "federraten", 235 and 140 N/mm for the ring.