My dampers are also Bilsteins for the RSR model so I think they are the same. The fronts have a bumpstop inside the insert/struts. The rears need a bump stop on the outside. They were of the 3-piece type, so due to the ride height I cut of "one piece" of three.

Thomas

 

My concluded advise is no bump stop at rear and I need order bump stops. Considering C2 original bump stop and cut it shorter or RS bump stop which is already shorter.

 

Power_up, I did find this on Pelican . . .

 

See the third post in this thread.

 

Not to add fuel, nor contradict any information from Bilstein, but here are some words of advice from our friend Steve Weiner:
SW-BumpStops
Bilsteins have internal droop limiters, but still require the external bump stops to prevent the piston from striking the oil/gas separator.

RS's had single-tube struts slightly shorter than OEM & shorter shocks than regular 911's had; the RSR had shorter double-tube struts and shocks than the RS to maintain full suspension travel at low ride heights.

Its imperative that each person ensure that they have proper suspension travel otherwise they risk ruining their shocks as well as suffering a myriad of handling issues.
__________________
Steve Weiner
Rennsport Systems
Portland Oregon
503.244.0990

 

And an interesting technical article on the function and contribution of bump stops to the overall performance of the suspension. There are additional files with the charts and tables, but I need to figure out how to load them, as they are currently too large.
Beware: this article is about 996 suspensions but the first principles of physics still apply.

 

Yes yes, I read this too. Thats what make bump stop issue for rear is unclear.

 

Thanks Richard. I read that too. Thats why I get both answer. And your answer from Bilstein is authoritative of course.

 

Learn much more

 

this is the number I called in 2009. They were very helpful. Note that their Bilstein's website lists a HD shock (yellow) for the rear of my '93 964 C2 that doesn't look like the Bilstein HD (silver) that I bought from shox.com:

AFTERMARKET & MOTORSPORTS HEADQUARTERS - WEST
ThyssenKrupp Bilstein of America
14102 Stowe Drive
Poway, CA. 92064
1-858-386-5900

 

Thanks. did yellow is old version? Seems now all are silver.
BTW, about Shox, are they on holiday now? I submit the quotation form few times recently but no response. Because I am not in USA and not good speaking english, I just can contact them through email or web form. Anyone have idea?

 

Did you use dust boot at rear?

 

Update:
Finally put on the Bilstein HD and eibach pro kit springs.
For the rear bump stops as the subject stated, I ordered RS shorter bump stop and also original c2 dust cover for rear shocks.
The car is lowered but not as low as H&R greens. IMO, the stance is nice. From the photos, the front is the lowest setting I can set. Eibach spring not too stiff. For street use, they provide comfortable ride.

 

Hi Power Up,

Thanks for your post. Do you have the part numbers for the RS bump stop and the dust covers?

Thanks!

 

That stance looks pretty good to me my HD`s are lying on the bench waiting to be fitted, I put the old 3 layer stops back on, does anyone know the difference in length of the standard ones to the RS ones ? I may still cut them as Thomas has done as they slide all the way down the Bilsteins unlike the boge which retains them at the top of the piston (slight difference in rod diameter)

This is one of those things that bounces round various threads, lets get a decisive answer on this do we need bumpstops on rear Bilstein HD`s and if so what size.