DWS964

The Bilstein shocks on my C4 have at least 70K on them, and I thought I would have them rebuilt while I'm in there with rebuilding the axles, control arm bushings, ... etc. I thought/assumed they were aftermarket Bilstein HD, installed sometime around 2000, yellow painted body on fronts and plated finish on rears.
- has anyone had experience with having the shocks rebuilt
- however, when contacting the rebuild service at Bilstein, and after struggling to find part numbers on the shocks, the tech said that the shocks must be OEM made by Bilstein and they cannot/will not rebuild them. These part numbers do not match any listings for current Bilsteins (B6), as they no longer list the "HD" or "Sport"
Front right - 99 064 0385H000
front left - 99 064 0384H000
rear - 3211547 (?)

Any thoughts or suggestions? Yes, I'm (always) on a budget (cheap). Planning to keep this car until I'm dead. Do not daily drive it anymore. LIkely will be used for fun at DE's and instructing. I'm tired of trying to be faster than the guys with cars 26 years newer than mine. And, I'm having way more fun with it.

Blu RS

Clearly those shocks are not OEM so they may in fact be rebuildable. Suggest you contact Performance Shock Inc. out in Sonoma, CA since they are factory authorized to rebuild Bilstein and other major brands. You'll want to speak with Thomas Haugg at the number below. I have no affiliation with them but may eventually use them to rebuild my old Bilsteins as well. Good luck!

Performance Shock, Inc. (PSi)
Dealers and Service Center for Öhlins, Koni, Penske, AST, Moton, Bilstein, Sachs and JRZ Shocks.
Dealers for Eibach and Hypercoil and Goodridge Fluid Transfer Products!
http://www.performanceshock.com
Phone (707) 938-5664 ext. 102
Direct (707) 934-4187

1-800-965-5664

Slow RSA

if you're interested in an upgrade at all, and if the c4 shocks are the same as a c2, I have a set of Bilstein RSR's sale:

https://rennlist.com/forums/parts-ma...-and-more.html

Bill Verburg

Only the mono-tube Bilsteins are rebuildable, The oe Bilstein fitments on 964RS and 993RS were twin tube, as are some aftermarket versions

DWS964

Thanks Bill, always a wealth of information. So with this in mind, would the shocks installed on my car be rebuildable?

DWS964

What is the definition of "RSR" ? Thus, what springs could/should be used, recommended ride height, do these use monoball upper mounts or can stock mounts be used, ...? I'm interested.
I have used the HR reds (too low in front with the current shocks), and RoW Turbo S springs (blue+orange marks) that allow me to run RS spec +5mm with plenty adjustment on current shocks.

Blu RS

Is it possible Mr. Verburg is not always 100% right?

I'm been running Euro 964RS front struts on my RS America and have been in communication with Performance Shock (PSI) about rebuilding them. I've sent them pictures for corroboration even though at first they said they probably couldn't refurbish them. Upon further consultation with Germany here's the response I got back from Thomas Haugg of PSI several months back.

"These should be serviceable. The only issue we may run into with them is due to a shaft diameter that Bilstein went through a while ago. However new shafts are pretty inexpensive. Once we get them here and inspect them, we’ll let you know the full cost before we proceed. Estimated cost is $275 each including replacement DU bushings in the strut housing, revalve and service.
The dampers are all monotube, with the fronts being inverted monotube dampers. The revalve to limit dive should also be straight forward.
Our current turnaround is 2 weeks."

So my question is just how much trouble can it be to call a company that actually rebuilds Bilsteins and get an answer from people who do it for a living? If your aftermarket Bilsteins are in fact monotube then there's a good chance they will be rebuildable.

DWS964

Blasphemy!

Bill Verburg

It's possible that he's wrong, but not this time

The 964 & 993 RS both certainly used twin tube Bilsteins in the front.
If you think I otherwise I refer you to
Porsche Information Technik '92 '911 Carrera RS' WKD 497 610
Porsche Information Technik '96 '911 Carrera RS' WKD 499 620

The relevant RS parts #s end in .80 for 964Rs and .81 for 993RS
I know for a fact that these are not rebuildable or revalvable by Bilstein

The Cup versions of both however use mono-tube Bilsteins, I know for a fact that these are rebuildable and revalvable because I use a custom revalved version on my car

John McM

I can add a data point here. I have RUF Bilsteins. During a spring change the mechanic sheared the top off the shaft of a front shock. Rather than go new I had the full set rebuilt. The cost however exceeded the set of new B6.

The only reason I refurbed rather than replaced is because my car has the RUF suspension pack and I wanted to keep it intact (springs excepted). I doubt refurbishment is economically better than new.

Bill Verburg

There are tw reasons to rebuild shocks
1) damage/wear
2) change the valve character

as to #2, stock Bilsteins like b6 or b8 come w/ a generic linear valve pack, these used to be called hd. They work well w/ stock springs in street use on smooth roads. A digressive valve pack w/ custom valving matched to the springs and car weight and use can change 'work well' to work great. When they are right they are almost as good as really high end adjustables, w/o having to go through the adjusting process.

All the modern adjustable that I know of come w/ digressive valve stack, and adjustable rates, the really high end ones move beyond that.

Blu RS

I suppose it's possible that the Euro 964 front struts I've had for years are in fact Cup struts rather than RS struts, which is what I thought I was buying. And by the same token it may well be possible that RUF Bilsteins are Cup based as well. So in the end, it may well be possible that once again Mr. Verburg is correct in his guidance regarding the non-rebuildability of certain Bilsteins.

In any case, I'm just glad to know that my Bilstein set is rebuildable although the economics of doing so is questionable. Further, the logistics of dealing with a "beached" vehicle for weeks while awaiting a rebuild of shocks should be enough to give most people pause about the whole process anyway, unless one has a spare set lying around to serve as interim props. The combination of those two factors is why I'm still on the fence about doing a rebuild versus going with much newer technology shocks.

Bill Verburg

The bigger shops get an expedited turn around, mine only took a few days including transcontinental shipping 2 ways

Viperbob1

I love it when he talks dirty like that