KRA993tt

I just got back from VIR where I broke a right rear Pss9. This is the second one and this has happened with about 4 hours total time on the car after I had monoballs installed and the alignment changed. The work was done by an experienced Porsche shop but I can not understand what is happening. Both breaks are near identical, right where the upper shaft comes out of the shock. The shaft looks like it is pulled apart no bending at all. Open porous metal on the end of the shaft. The first one (Watkins Glen) we assumed manufacturer defect but now with a second failure I think it may be something in my set up.



I have the rear alignment at about negative 2.5 degress with RS type ride height, sway bars/droplinks. I drove the car on the street for about 1.5 hours before this latest failure and did not hear any rubbing or odd interference noises. One the track I never had any idea of a problem until I came off the track (after two 25 minute sessions and no off track four wheeling) at low speed 5mph and went over a jarring type bump and heard a rattle.

I can not imagine the force it take to brake these shafts so cleanly.

Any thoughts or comments are appreciated??

Mike J

Do you have a picture of the break? The shaft should be stainless and not pourous. Maybe Bilstien had a bad batch of shafts. Even with lowered and negative camber that should not stress the shock...but it does change the static shock position. Mabye its bottoming out? Regardless the shock shaft should be able to take a lot of stress. Since the weight of the car is through the shock body and the springs I can't see the shafts breaking...very wierd (and a bit scarey)!

I would take both shocks to an engineer and get an opinion on what kind of breakage it is and then take that to Bilstien. If its their fault (likely) and it happened twice they should own up to the mechanic's bill for the installation at the very least, never mind the hazards that it could of caused.

Keep us up to date since the PSS-9's are pretty popular (including the ones on my car).

Cheers,

Mike

KRA993tt

Sorry I don't have a picture of the broken shaft. The first one is on its way to Bilstien and the second one is at the shop. I had a guy that works with metal (Jeweler) at the track tell me it should not be porous as well. He said part of the shaft looked ok (20%) but (80%) was porous. I don't know but I could see the difference in the metal he was talking about. I will see if I can get a picture. Other than the rattle I am not sure I would have noticed the failure.

dwe8922

You might not have spaced spring collar on the shaft down far enough from the monoball, which can cause binding at some point during shock movement. That can cause the shaft to break at the base of the monoball mount, which I think is what you're describing.

KRA993tt

I had the same basic set up prior to the camber plate monoball setup. I don't think anything would have really changed when the camber plates were installed but maybe they were not right before. Thanks for the input I will have it checked out.