Burn Meter

Car cracked 30K miles over the weekend and the suspension is due for a refresh. I'm to get opinions from folks who have recently used the Bilstein service. Did the result meet your expectation? Do you consider it a good bang for buck?

I've found some older threads, but I'm hoping to get some fresher perspectives.

My car is under no circumstances a track car. Weekend drives and spirited mountain drives. Living in New England, even the desolate mountain roads are very bumpy. Current OEM setup does not play well with those roads.

modoz61

You don't mention whether or not 997.1 or .2

But for what its worth and the driving you describe, have the Bilsteins checked, refurbished if needed.

Then add DSC module to replace the OEM PASM module.

that will take care of the bumpy mountain roads in New England nicely. (I live in Boston for 3 years and know what you mean for road conditions)

Burn Meter

My car is a .1

The other issue is the according to the Bilstein Service site the lead time for revalve work is now 12 weeks.

Tom@TPC Racing

As far as I know, Bilstein USA no longer services OE PASM shocks. Perhaps because not wanting to compete with OE PASM shock sales or for OE contract reasons or some other reasons. They do service the B16 Damptronic which is their own aftermarket variant. May be now the OE contract has expired or something...

I have found the OE PASM shocks to be very durable in general. You could simply do the old fashion bounce test with the ignition turned off. Its not very scientific but it'll let you know if there's a bad seal or cavitation in the shocks. With the ignition turned off the internal bypass valve defaults to closed position making the damping full stiff. If it doesn't bounce or sink down then the seals are holding and there's no cavitation. The bounce test will let you know if you have a blown shock. Most drivers can feel if there's a blown shock by driving. Its not as easy to determine by bouncing if a shock's damping has gotten a little weaker rather than completely blown. You'll need a shock dyno with some sort of DSC simulator to do such a full test. Due to the complex nature and time of such test, the cost will be half way there of buying new shocks. We do have a DSC simulator on our shock dyno but we only use it for development projects, not for service.

For what its worth, I have driven many cars with OE PASM shocks that has >50K miles of combined street and track use. They work fine. I agree with Modoz61 that DSC is a good option to have control over the damping for your liking. Without a DSC simulator on a shock dyno, the technician can add or subtract shims but doesn't have a way to test the results at the different PASM command ranges. The technician can apply a fixed amount of electrical current but this presumes the shocks only operate on the car with this particular fixed current. If you want the shocks to be permanently softer or stiffer then adding or subtracting shims will achieve this same as in any non-electronic convetional shocks but having electronic control makes this more than a conventional procedure.

Burn Meter

I'm somewhat inclined to believe the OE maybe on their way as there seems to be a distinct clunk sound when a bump is it. I'll message Bilstein and see what they say.

Tom@TPC Racing

If the clunk is from a front shocks its likely the bearing that goes between the inner and outter tube, which is external of the valving. The valving is concealed inside the inner tube(aka cartridge). If clunk is from the rear check to see if the bump rubber is still in place. If not, then the rears are likely bottoming.

Burn Meter

Tom - is there a diagram or part number I can reference to view that bearing? I hear noises from all 4 corners, so I'm inclined to believe the entire suspension need form of refresh.

Tom@TPC Racing

Google search Inverted Strut Bearing.

Burn Meter

Tom you are correct - they do not rebuild OEM parts.

Protocav

FWIW, I previously worked a block from the Bilstein USA HQ in Poway, and I went over there to chat with one of the engineers regarding the rebuild. They said that the OEM shocks are not rebuildable (which I think is false) and that I would be better off buying new. They actually thought I was mistaken that I heard they did this type of work, so I got the impression that they were not at all interested.

Additionally, I had a clunk in my suspension twice. one time it turned out to be a loose sway bar end link, and the second time it turned out to be the spherical bearings in the OEM upper strut mounts. These are not rebuildable, so I went with the Tarett solution, and have been very happy ever since. high quality parts that can be rebuilt for very cheap:

http://www.tarett.com/items/996-997-...lta-detail.htm

sfo

thanks, very helpful

Tom@TPC Racing

Welcome. Here's our shock dyno station and our custom made DSC simulator. We this equipment and race engineering experience we damn near nail down the damping before the shock goes on a car.

Gadsby

Glen-yee in California is option to consider, rebuilt my 6gt3 last year to include Dyno before and after and verify spring rates.

cheers

RAudi Driver

I'm looking at these Tarrett's also and wondering, what do they do to the ride quality on the street?

I've got the front end clunk ut only hear it when i leave the house for about 1 block, then it appears to go away for the remainder of the day.

Protocav

The ride quality is exactly the same as stock, since they both use a spherical bearing design. The Tarett is rebuildable, however, and the new part is 20-40 bucks (each side).

To check the sway bar end link you need to jack up both sides of the front to make sure that the sway bar is not loaded, then jiggle both links to see if they are loose. If it's not that, check the upper spherical bearing mounts by lifting up on the wheel or brake rotor while the car is lifted. I could actually see movement (and definitely feel it) at the upper strut nut where it meets the spherical bearing. Just pull the frunk platic to see the strut tops.