I know. It often creates confusion.

When a kit is released in Germany they will send one to the California offices of Bilstein NA. Their tech department will evaluate the kit and install it on a car. They will then test drive it and work up a unique spec sheet on what they feel is best for U.S. roads and U.S. drivers. It is not uncommon for them to adjust the kit slightly for a specific desired result.

Look at Porsche. While it's not exactly like what we are speaking of, they too have U.S. spec suspensions and ROW setups.

 

44k HARD miles. They are really just squeaking alot (from the shock), still function.
Mike, any more track days this yr, I gots the itch to go out one mo time!

 

7 days left...

October 9th (Lightning)
October 27th (Thunderbolt)
October 30-31 (Lightning)
November 6th (Thunderbolt)
November 14-15 (Thunderbolt Saturday and Lightning on Sunday)

 

Can you put me down for oct 27th and i'll send you a check/forms etc.
tia
C

 

I trust your finding but this should NOT be the case at all if the installation is done correctly.
Lowering would cause excessive stiffness only if it's done beyond Bilstein's spec. This means 30mm plus, when the internal bump stop (a soft sleeve around the shock piston) is compressed beyond its linear range.

 

I got this kit: F4-GA5-D598-H0, which is the only recommended for the Turbo in the US. Note that this is the number for the whole kit, not the shock absorber itself. The shock absorber has a sticker with a different number: F4-GA5-D600-H0.

FWIW, some data that you might find useful: I called Bilstein way back when and got the same quote for range as Mike/AWE: 10-30 front, 5-25 rear.
I finally got around to measuring the ride heights of my car the official Porsche way. I have a diagram posted somewhere if you are interested: the measurement points are the bolt beneath the front lower diagonal arm and the locating bore between rear control arm and rear toe link. Much easier than I thought. So, in my car:
Front 110 mm
Rear 140 mm
If you like the way your car is now, you might want to measure just to keep track.

The stock numbers as supplied by Alex are 132 / 153 +/-10, making my car's drops 22 mm front, 13 mm rear (assuming it starts out the same as Alex's numbers). This setup has been test driven fairly hard (so hard I don't dare to ask him about it ) by Tom of Lucent, a seasoned Porsche setup man in LA, a number of times. Neither of us has ever noticed any problem.

Basically, by fender height measurements, my car's drop is about 10-15mm front and rear. By official measurements taken Alex's numbers as reference, the car has a slight forward rake with front dropping about 10 mm more than rear, closer to GT ride heights (not our goal, just coincidental as set by Tom), but not with the same degree of rake. (GT2 rake is even more pronounced, 110/147.)

 

Thanks, looking at some bilsteins and some moton clubsports.

 

Sure. You take the car to the track so much (probably more than most on this forum?) the Moton may not be a bad choice at all.

 

I have to say I am quite happy with the Bilsteins on the track. I ran it at a open track day at TWS, the car was very neutral, stuck like glue until I had a tire go away on me.
So my vote would be for the Bilsteins on a dual purpose car.

 

On 'normal' roads no you are right this is NOT the case, I don't get excessive stiffness. However on UK bumpy b-roads non-sport PASM is only 'just' tolerable at -15mm drop front and rear. Sport PASM is only good for really smooth roads or tracks.

So perhaps the roads you drive on are just a lot smoother than they are here? Or perhaps the -13mm rear setting you have Cannga helps with better traction. Or even perhaps the Porsche PWIS printout I took the factory number from is specific only for European spec cars and US spec cars have a different starting range than:

F=132 +/-10
R=153 +/-10

Or perhaps we all need to sell our Porsches and just buy Ferraris?!






(taken from a drive I did yesterday)
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I would never turn down an F car (so gorgeous) but it can't completely replace the Turbo. Torque is missing in action in comparison.

Kidding aside, re. the coilover, it's hard to establish a frame of reference for "stiffness," or what's considered "tolerable" by different individuals by writing on the internet. Let me try by giving some examples:

1. Assuming the pot hole is 1-2 cm deep and you are traveling at 40-60 mph. In my car, with the Tarett drop link, I would try to avoid this; without the Tarett drop link, I would be ok until oh, maybe 40-50 mph.

2. For a second "frame of reference," I test drove the following car back to back: Ferrari F430, Gallardo, Ford GT, and I've driven the GT2 on a second occasion, this is a very very rough estimate (no flame please guys ) based on 15-20 miles of driving, up to 100 mph: In those cars, in order of soft to stiff: Stock Turbo, F430, Bilstein Turbo, Gallardo and GT2, Ford GT.

3. With bigger bumps, say 2-3 inches or above, all these cars will jump no matter what.

So basically the Bilstein Turbo is in the middle of the pack when it comes to "stiffness"; it should NOT stand out one way or another. If anything, perhaps some of the more hard core track people think the Bilstein is too soft.
The only difference between my car and yours is the rear toe link and rear upper links (right now I am testing my car with the Tarett off). I am suspicious of the rear upper control links as the cause of your car's seemingly excessive harshness but I am not sure and have no direct experience with them.

 

UK roads do have pot-holes but they are easily avoidable. It's the actual road surface that is very uneven...

 

Sure. 2-3 years I drove a bit around southern England for a 2 week period (London, Cotswolds, Salisbury, Canterbury, Stratford upon Avon, Oxford, Windsor, etc.). I used the GPS and it did take me to some small roads a number of times, so I think I have some idea of what you are talking about. That kind of road undulation as shown in your picture should not cause much trouble, at reasonable speed.
At any rate I remain quite puzzled (and I trust your findings). I assume your tire pressures cold are around 31-32 front, 36-38 rear?

 

I do some high speeds over such terrain so my cars needs to feel extra planted ie. all 4 tyres need to be hugging the road surface at all times for which I need extra compliance. This is why I also run GMG front sways at softest setting as otherwise it can make the car too stiff when twisting and I loose traction.

My tire pressures are set to OCD levels (with nitrogen in) so certainly no issues there.

Who knows, perhaps it is the GMG rear toe-steer kit or the GMG dog bones stiffening things up further.