Bilstein shock info

[Bill Verburg]

I am utterly confused

I have communicated w/ Bilstein US technical dept. twice now

once in 2019 and once this past week looking for confirmation

In both, Bilsteins asserts that all 911 b6 & b8 for street use are digressive and that only the motorsports shocks like the 993 Cup shocks are linear.

I don't know what to believe any more as all the dyno plots for street b6 that I have ever seen indicate linear

[r lane]

I would think that Chuck at Elephant Racing would have a shock dyno as he sells different shock setups in the Von line which I think are Bilstein and he would have applied info. Why would you go digressive for a street setup. Bob

[Bill Verburg]

Originally Posted by r lane

I would think that Chuck at Elephant Racing would have a shock dyno as he sells different shock setups in the Von line which I think are Bilstein and he would have applied info. Why would you go digressive for a street setup. Bob

digressive gives better low speed(maneuver) control and doesn't have the virtually unlimited high speed resistance of linear valving

I trust Chuck to be straight w/ info and he says linear for all

I just don't know what to make of Bilstein Technical's response as it makes no sense and totally disagrees w/ what I've seen

My 993 Cup Bilsteins were certainly linear and revalved to digressive by Bilstein San Diego before installation

Bilsteins also say that they no longer service shocks and recommended
Performanc Shock
for any service or revalve

[r lane]

To understand digressive and maybe I don't. In what I think is rebound, as the car is lifting on that corner, the more aggressive that move, the stiffer the shock becomes during that action. My understanding. Bob

[Bill Verburg]

Originally Posted by r lane

To understand digressive and maybe I don't. In what I think is rebound, as the car is lifting on that corner, the more aggressive that move, the stiffer the shock becomes during that action. My understanding. Bob

Just for discussions sake, here a 2008 RSR front, digressive in both bump and rebound

the characteristic are early ruse and then a nice flattening as piston speed increases



here are 2 linear and 1 digressive for comparison, not the unlimited increase in damping force w/ increasing speed associated w/ linear, only Ohlins to my knowledge, adds a blow off valve to limit this


here' s MCS 2way




the thing ,I don't like about these curves is that they all use the computer to zero out the gas preload


here's one w/o the base preload zeroed out, it better shows what's going on

[nickelplated5s]

BV, I happen to have a quote from Chuck here. Von level 2's per Chucks advice along with bushings and such, waiting for input from a shop I'll probably use. Might go for new spring plates as it will be quicker than sending mine out to replate. Give me a few months and I'll post. Bil rears now. PeteKZ will probably come drive it and give a third party opinion.

[ericwitte]

FWIW, I installed Chuck’s Vons shock on my 72 years ago as the sport and HDs were progressive and Chuck’s were digressive.


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[Bill Verburg]

Originally Posted by nickelplated5s

BV, I happen to have a quote from Chuck here. Von level 2's per Chucks advice along with bushings and such, waiting for input from a shop I'll probably use. Might go for new spring plates as it will be quicker than sending mine out to replate. Give me a few months and I'll post. Bil rears now. PeteKZ will probably come drive it and give a third party opinion.

I did ask Chuck if the Vonns were digressive but didn't get an answer, we got distracted by something else

did you?

[Bill Verburg]

Originally Posted by ericwitte

FWIW, I installed Chuck’s Vons shock on my 72 years ago as the sport and HDs were progressive and Chuck’s were digressive.


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To the best of my knowledge all 911 Bilstein hd and sport f&r have linear valving
I base this mostly on this sort of shock dyno chart

again gas pre load has been zeroed out and I wouldn't be happy w/ the exhibited digressive curve, though it is better than the comparison linear curves


I do believe that Bilstein non Porsche 911 b6 may be digressive and suspect that the tech reps just didn't really investigate deeply enough even though I was inquiring specifically about '70s thru current Porsche 911 g body shocks

[nickelplated5s]

Part # for the B6?

[fanaudical]

Originally Posted by Bill Verburg

I did ask Chuck if the Vonns were digressive but didn't get an answer, we got distracted by something else

did you?

I have Von's Level 1's on my '75 Targa. I can only find the charts for two of them, but they are digressive (though not by much - the curve looks similar to the above post).

I will scan and email the charts to you, Bill - It will be an honor to provide you with a chart/data for once. I wish I had your database...