I'm trying to troubleshoot a crunchy noise when going over speed bumps and other large bumps in my front right suspension. I've eliminated many things: sway bar bushings, drop links, upper and lower ball joints, tie rod end...

So today I compared my right (noisy) struts to my left (good) struts and noticed a few differences. Could any of these cause a crunchy noise:

1. Right spring does not look seated properly in the top washer. It looks like it should be rotated another 10 degrees so the end of the spring stops in the washer.



2. Top of right suspension looks like it is missing the mounting (928 343 051 01) or something else. Note: Left side is higher than right side. Is there something missing on the right side?
Image orientation: Right side / Left Side


3. It looks like the right strut is missing the additional spring (928 343 527 02) between the strut body and the protective tube. Could this cause over-compression of the strut when missing?
Image Orientation: Right side / Left Side





Could any of these differences be causing a crunchy noise on the right side during large movements?

4. Side question. Are these Koni Red struts adjustable with this tool?
https://928motorsports.com/parts/shocktool.php

Thanks

 

Probably best to remove and inventory all the pieces in the coilover assembly. It isn't really a "strut". The spring, once unloaded by lifting the car, can be rotated to get the coil end seated in that upper saddle. There's obviously a difference between the two, but it's hard to tell exactly what's not in the right place. The rubber bump-stop (#5 in the PET diagram) is visible in your left picture/right shock but not in the other; That may be because the bumper is up inside the plastic shield/collar -- you can probe for it with a piece of wire. If it's truly missing and you car has sagged on the springs, it would make some noise at full shock compression.

AFA adjusting Koni's, on other cars I had to do all adjustments with the shock fully extended, Then turn the rod while holding the body and I felt for the detents. Call Carl at 928 Motorsports and ask him directly about the tool. He'd love to help you.

 

Is part number 10 from the diagram above installed upside down on the right side?

 

In picture 3 above, the secondary bumper pad on the right side could just be stuck up higher under the dust boot, whereas the left side one could have slid down.

 

Thanks Dr. Bob. I will pull it out and get this sorted. I checked for the bumper inside the dust cover. It is not in there. I just ordered it.

That seems to be absolutely correct! I found this image on 928motorsports.com. It looks like when the mounting is installed upside down, the shock can over-compress, especially when the bumper is missing in my case.



I bet the shock is bottoming into the adjustment mechanism on the bottom.





It's not there. I just ordered it.

I hope to get some time to pull it apart this weekend. I'll report back. Thanks.

 

I agree the problem is most likely in the top mount (item #10 in your Porsche diagram).

We have started to see these failing, allowing the suspension to collapse. I punched my first one out during Pikes Peak in 2007.

It caused me to come back and make this billet replacement part:
https://928motorsports.com/parts/front_spring_perch.php
NOTE: this part will only work with 2.5" diameter springs.

 

The secondary bumper pad probably got mashed flat and destroyed itself. Sad to say it gave it's life to save the shock when it did bottom out.

 

Thanks Carl. I'm not yet ready to change out springs, but this looks like a great option.

Do you think your koni shock adjustment tool will work with my koni shocks:
https://928motorsports.com/parts/shocktool.php

Thanks

 

John,
I have Konis on all my cars. That is the exact tool I use to adjust mine. I just got mine from a different supplier.

 

As long as your Koni's have a 5mm or 6mm Allen-socket head in the top, yes. Let us know which size you have when you order.

 

I've learned an important lesson. Don't tackle a job unless you know you have the parts you need to complete it within the allotted time. Anyway, I took the coil over shock out to flip the top mount which was installed upside down. I thought that this job would be easy with the "Just remove the fender liner method", but this did NOT work for me.
https://rennlist.com/forums/928-foru...ml#post3066741

I notice in the pictures on that thread that the lower mount is removed despite the text saying that its removal is not necessary. Next time I will move the adjustment collar to raise the ride height to try to get the top of the mount enough room to move aside. My front ride height is currently at 165. It looked like I needed more than 15mm (0.6") to clear the top of the assembly so I ended up pulling the lower "wishbone" off to get the coil/shock assembly out. Disassembly ended up being a major PITA.

After compressing the springs, I flipped the top mount (which was installed upside down by the PO) and reassembled without the missing rubber bumper between the shock and the dust cover (shipping not due til later this week); hoping that would solve the problem. Bad call. I should have waited for the part, or left it disassembled. I still have the crunchy noise when going over large bumps.

Now I wonder if I should be replacing the spring[s], the next time I tear it apart to put the rubber bumper in. I have a feeling that the "crunchy" noise that I hear may be the coil spring bottoming out on itself (because the rubber bumper is not there). Dr. Bob got me thinking about spring sag. It's a 31 year old spring with 140k miles on it. There are no other obvious signs that the spring is bad.
How do you know when to replace coil springs? Where do you get them? I'm not ready to change everything to the 928motorsports setup.

 

Coach --easiest diagnosis on springs is whether you can get the car to your desired ride height. The adjusting collar on the front threads over an amazingly tiny (maybe 8 threads tall) sleeve on the shock, so it's possible to screw the outer adjustment collar up so it's sitting on the inner sleeve with no threads engaged. Watch at the bottom of the adjuster, making sure that you can't see any of the little sleeve. You can use a thin pocket scale to find how much room you have inside the adjusting collar.

I found a set of GT/sport front springs after the originals (at 90k at the time) were having trouble adjusting to keep the front at the original factory ride height.

 

Coach,
If you determine that you need to replace your springs, I'm pretty sure that 928 International in Anaheim has all the springs you could ever want.

 

Im back to square one in diagnosing this crunchy noise. I reinstalled the top mount in the correct orientation and I installed the rubber shock bumper. Noise is still there. Other facts about the noise. It starts out very noticeable, but as I drive a bit (15 minutes) it get quieter. They lead me to believe that I might be rubber loosening somewhere.

I notice that my lower control arm bearing rubber has been pinched by the mount. See the circled prt



Could this be causing a noise? Is there anything to do to lubricate this rubber? As far as I can tell, the rubber is not replaceable without replacing the entire lower control arm.

 

^^^ thats normal.