Bilstein Struts - When to Replace??
 

Having finished my project replacing all the suspension bushings with the Elephant rubber ones, I am getting ready to dial in ride height and get the car aligned. But I am pondering whether I ought to replace the Bilstein struts and shocks first. The car had Bilsteins originally, and in 1988 I had the front inserts and rear shocks replaced with (as I recall) the standard Bilstein parts, or whatever would have been "stock" at the time. That was at about 100,000 miles, give or take.

The car now has about 160,000 miles, and all of that has been routine street use (sometimes sporting), on generally decent roads. The old "push on the fender" test shows each corner rebounding and stopping - no oscillations - and the struts and shocks are still pressurized, based on my handling of them during the bushing project. But, especially at the rear, the force needed to depress the corner of the car seems light, as though there is not a lot of resistance.

The car drives fine and I don't notice any bobbing/swaying that I think you normally would have with a bad shock/strut. The ride is great on a smooth road but still harsh on the lousier roads around here (e.g., the atrocious pavement on I-5 around Seattle, and most of Seattle surface streets for that matter). So, I am wondering if there is some damping that has gone away in the 23 years those Bilsteins have been on the car. :confused:

If anyone has suggestions for a better way to test the struts/shocks and decide whether they ought to be replaced, I would love to hear it. The job does not appear to be too hard, and the parts (looks like ~$600 or so for all 4 corners) not too bad, but on the other hand if the ones I have are still OK then I would just as soon leave them on.

If you can stand not driving the car for a bit the Bilsteins can be rebuilt and while in there can be revalved to more precisely match your torsion bars and speed. Cheaper too.

http://forums.pelicanparts.com/porsche-911-technical-forum/628415-bilstein-revalve-shop.html

The old "push the bumper" test will not work on the 911's...

if you are the original purchaser of the shocks(and I suppose still have the sales receipt- i kept mine) you can send them to bilstein(they have a lifetime warranty for the original purchaser) to have them tested. I sent mine out after 120,000 miles of owner ship. One front shock was slightly out of spec and the replaced both fronts free of charge. The rears tested out perfectly and supplied me with a dyno print out and returned them to me. Jerry

Thanks for all of the above feedback. I am not so concerned about cost - though less is always better - as much as "do they need replacing"? Amazingly enough, I do have the original receipt for the rear shocks (which I installed myself) and also the one from Meaney West for parts and labor on the front inserts, so maybe getting ahold of Bilstein is the next step. :)

When i replaced the rear shocks, the left rear ended up about .5" higher and i could no longer adjust my rear swaybar easily. The left rear was shot but the right was ok. Now it needs to be recorner balanced.
IMHO
Since youve gone this far, do the shocks ans struts and avoid doing the cb twice

Thanks VFR, I was wondering about ride height effects from new shocks and struts, and was leaning towards just doing them now, and be done with it, before spending the $$$ on the full alignment and corner balance - your experience supports that game plan.