Question on my revalved Bilsteins (Is Wil around?).

[David]

I just got my got my rear Bilstein sport shocks back from Bilstein. Considering one was noticeably worn, I think the $65 each is a great deal. I sent them the following info and asked them to revalve them for my car. I don't have a feel for what the damping force should be so I'm curious if any of you (like Wil Ferch) have any comments on the data. I just eyeballed the data from the two data sheets and plotted it, so the data is rounded and averaged.

Car details:
2800 lbs without driver
2970 lbs with driver
38/62% weight distribution
22mm/31mm front/rear torsion bars
22mm front & rear sway bars
New Bilstein sport front strut inserts.
Euro ride height
275/40-17 front tires
315/35-17 rear tires
~550 fwhp
Car used for track days, autocross, and weekend street driving.

[johnsjmc]

I have a very similar setup with a 3.6 in an Sc . 23/30 hollow torsions,21/22 Carrera sways and 215/45x17 and 255/40x17 tires. I am revalving my front and rear and Jack French at Bilstein recommended 235/120 fronts and 360/140 rears ( ratio of rebound to compression)I use the car 99% on the street . I think he said these setting would be between HD and sport on the compression side and closer to Sport on the rebound. His reasoning was that the stiffer than stock torsion bars would take away some of the need for compression control but the rebound needed to be controlled better or more.Do you have any numbers quoted like this?

[Noel]

For my stock SC with 22/28 torsion bars and Carrera Sways Jack French recommended 365lbs/125/bs (Rebound/Compression) for the rear and 220lb/110lb (Rebound/Compression) for the front.

I love the setup!!!

[David]

After converting to lbf from N it looks like the shocks are valved about 760/320 rebound/compression. This should be interesting. If it's too stiff, it's only $65 each to try something else.

[David]

Another thought, with shocks this stiff I guess I should go ahead and add gussets to the shock mounts. Anyone think it won't be needed?

[Noel]

Originally posted by 125shifter
Another thought, with shocks this stiff I guess I should go ahead and add gussets to the shock mounts. Anyone think it won't be needed?

It definitely wouldn't hurt. Plus, it is easier to do this now than deal with a broken mount later, IMO.

[Wil Ferch]

I'm occasionally back on this board ( since you asked...still in Germany on assignment...still very busy and squeezing a few minutes on this board)...

Rebound / jounce ratios of 3:1 or so are common...that just speaks to the ratios...the absolute force values can still be stiffer / lighter overall. These numbers also represent the "peak" values and we can't see the "curve" generated by the shock dyno. This is very much like knowing the peak hp and torque of an engine without having it graphed to show the "other" numbers along the way...still very useful information.

Mercedes used to stand out among production cars in using close to 4:1 ratio ....and I think they know a thing or two about shock valving characteristics.

Find my other post about the Road & Track article of (?) Oct or Nov '74 where this topic was covered in great detail. Never saw something as good since. Perhaps some folks can find that post ( to zero-in on the right article)...and scan the graphs and text ??

- Wil

[David]

Since I've finally driven my car with the new suspension setup, I thought I'd revisit this thread.

I haven't driven it that hard yet, but so far I'm very pleased with the shocks. While the numbers would make you think they'd be very harsh, they're not too harsh on the street.

I lowered it to 25/24.5 (so I guess I'm lower than Euro height) and the bump steer has gotten worse so I guess I can add something else to the to do list.

I'm planning to use 255/40-17 front tires instead of the 275's I originally planned. I figure it'll be more street friendly. If it doesn't work on the track, I guess I'll go wider and/or get different track wheels.

[len911]

I just went through this a couple of weeks ago... They sent me a dyno sheet and took me a while to figure out what I was reading. Your shocks are 340/142 (they show as 3400/1420, last numbers on the table) Seems that the industry obtains data in Newton/m but reports them in 1/10th the value. Search on Google for "Bilstein shock revalve" for some interesting articles... Lou

[David]

Well that makes more sense. They don't feel overly stiff. Of course I couldn't even compress them by hand.