Noise from RR shock tower

Zeke · 03-23-2008, 03:33 PM

I have a loud noise like a broken sway bar mount coming from the upper region right behind the passenger's head. I have checked things like motor mounts, links, the sway bar itself and the coil over ass'y and can't find anything obvious. This leads me to believe it's internal to the shock itself.

The nature of the noise is not a rattle but a single knock each time the car hits a seam in the road or other light bumps. Normal suspension travel either driving or bouncing the car will not make the noise. In fact, I can't reproduce the noise in the garage no matter what I do and I've experimented a lot. I've even suspected the door, but for now I'm convinced it's behind the door. Tapping on the pinch seam at the top of the rear fender well does locate the direction of the noise when my wife sits in the car and I experiment. She knows the noise as she is the primary driver.

So, I turn to your thoughts on this. Take the shock out and have it tested? OH, BTW, she was forced over on the street by another driver and curbed the RR wheel. It's still straight, just has some rash on about 1/4 of the surface. I can't imagine this ruining a shock, but maybe it did.

What do you all think?

Flieger · Flieger's Garage

Same problem occurred on my 2002 Boxster S. The clunk would happen especially over speed bumps. I took it to the dealer under warrantee and they diagnosed a broken right rear strut mount. I am not sure how "broken" it was as far as pieces coming off etc.

The strut mount was replaced and problem solved.

Zeke · 03-23-2008, 06:43 PM

Thanks for your reply. I can say that a speed bump would not trigger this sound. A waffle iron road would.

BT911 · 03-27-2008, 06:38 AM

have you checked the ball joints for the rear trailing arm? seen these ball joints go bad

Zeke · 03-28-2008, 12:29 PM

Quote:

Originally Posted by BT911

have you checked the ball joints for the rear trailing arm? seen these ball joints go bad

I had the car up on stands and I tested the wheel for movement. I didn't get any, but that is not a very good check. Before I pursue this thought any further, I'm going to assume that a bad BJ would make noise all the time, not just when the car is lightly rattled.

Remember, I don't get any noise in turns, under braking or acceleration and not over dips and bumps. Only the smallest suspension movement makes the noise like when I hit the seams in the road at any speed.

BT911 · 03-28-2008, 03:34 PM

swap the rear trailing arm from side to side and see if the noise moves to the other side. the trailing arm is the one that attaches to the lower control arm and goes to the body right behind the fire wall

Zeke · 03-28-2008, 05:03 PM

The noise is on top at the tower.

Flieger · Flieger's Garage

#11, the strut bearing was my clunking noise over bumps.

Zeke · 03-30-2008, 08:04 AM

Thanks for your PM and correction that your front bearing was the culprit. Now that I know about these bearings, I'll check all four.

Zeke · 06-09-2008, 05:27 PM

Still there and worse. Only at low speeds on rough surfaces. Sounds like it's coming from the door sometimes, but I've opened the door and shook it as much as I could. Nothing. I even had the side vent out yesterday reaching and tapping everything all the way to the fan. All is tight.

This is really getting annoying.

Zeke · 12:50 PM

Noise always stops over 20 MPH. I feel like I can touch it, but I can't. The rear doesn't have a "bearing" such as no 11 above. I guess I'll give up and turn it in to the dealer for repair.

Robman · 07-06-2008, 11:29 PM

I think my 99 has the same issue. Driving over markers on the drivers side it sounds like normal bumps on the road. Drive over the pass side and it sounds hollow and becomes intermittent at different speeds.

I'm pretty sure its in the suspension somewhere because I've tried to rattle everything stopped, took off the rear tire and inspected, and found nothing.

We'll see if it goes away when I step up to PSS9s.

By any chance do you run 18s?

Zeke · 07-07-2008, 07:56 AM

17's.

zoomie · 07-21-2008, 07:54 AM

Replace the rear control arms. The ones from the rear firewall to the strut. Easy R&R in the driveway. This is a common issue.

Zeke · 09-18-2008, 05:14 PM

zoomie, you were right on the money. they are actually called links and I would have found this sooner if I knew the vernacular.

DCinVA · 06-22-2009, 11:25 AM

I am chasing this same issue. Could someone identify the that part that corrected Milts problem.

Sboxin · Sboxin's Garage

Part # 8 is the link Milt is talking about -- the bushing on the body connection end is what fails and sounds like it could come from the top of the strut tower.
You might find a good used part at a Porsche parts recycle place...

Good luck and take care,

Ed

patkeefe · 08-24-2009, 02:32 PM

I seem to have this same issue. Is it the bushings at the end of the rod gone bad? It really is annoying. I had the car checked out when I bought it, and it has been deemed track-worthy, but this noise is hideous. Especially over low speed bumps, like holes or uneven surfaces in a parking lot.

patkeefe · 07:52 AM

Well, I can't stand the noise any longer. I seems to do it at higher speeds now, and I'm getting worried about it. I suppose I should change them as soon as I get the SC back together.

Can someone verify it is is a 986-331-043-04 which seems to have been superceeded to -07? Edit:
I verified it by actually crawling under the car. I jacked it up, took the wheel off, and cannot duplicate the sound. I can get the suspension to clunk when it is fully extended, but that is obviously not the problem.

Wayne 962 · Wayne 962's Garage

You know, I would check the convertible top cover first - drive around with it slightly raised. On one of the book's project cars, this was making a huge rattle that disguised itself as a suspension rattle.

Other than that, you need to get the car on a lift and just ferociously "wiggle" everything to find the problem. The Boxster rear suspension can be difficult to diagnose in this manner...

-Wayne