Oddjob

Spring is rubbing the shock body. Seems to be a new problem, did not do this in the past. Possible that it started occuring with the most recent spring change.

This side (driver side shock) is significantly worse than the p-side shock. It is somewhat worse than the picture shows, the threads are galled nearly to the thread root in spots. The p-sde side has just a slight "brushing" in a small area.

Gap between the coils and the shock body is about 3/32" to 1/8", so quite a bit of distortion taking place for it to contact. Assuming the spring is buckling somewhat when compressed. Looks to be seated ok, not uneven on the perches.

Possible the rod bearings are going, and the rod is tilting when compressed?

Matt Romanowski

Lots do it. It's from the side load the spring makes when compressed. It also puts side load into your shocks. That is why Hyperco made the hydraulic perches.

Oddjob

Thanks Matt - I knew the hydro perches existed, but never really looked into it before.

I had thought these and the TRB (torsional release bearings / torrington needle bearings) were primarily for strut applications where the strut body pivots with steering, but the upper spring seat is stationary w/ the car body - causing the spring to twist.

The video is interesting to see the movement and rotation of a spring when compressed. [EDIT: video apparently no longer is attached to this page, and can't find it again]

http://www.hypercoils.com/spring-perches.html

Also thinking about trying a shorter spring, and lower the upper seat (so less of the shock body is inside the spring coils).

JoshuaB

I had the same problem (on a non-Pcar with Motons) and it was a result when the car was lifted (jacked up/on a lift) and the springs becoming unseated.

I was able to fix the issue with tender springs that kept the main springs located…

Oddjob

Joshua,

The suspension is actually at full droop in the top picture, so the springs never come unseated. They do on my front struts so I know exactly what you are talking about, but not on these rear coil overs. The rubbing here is occuring when the car is driven, which concerns me somewhat more.

EDIT - added pics after pulling the shock.

Matt Romanowski

You could use these to stop it too. http://www.hypercoils.com/bellows-springs.html

JBreckeen

Hey.

I had the exact same thing happening on our 951 race car with custom front stuff. My mechanic (who knows race cars) wasn't too worried as the very hard steel spring was rubbing on the soft aluminum threads - the threads were losing. It hadn't even taken the paint off the coil springs.

And like yours, the area of mine that was rubbing was nowhere near where the perch would be.

Now saying that, I recently rebuilt the front struts and found the damper rods were warped from track abuse - I will see if the rubbing stops. . . .

J richard

^this. A little rubbing is typical as Matt said, yours is excessive. You may have a bent strut rod.

Matt Romanowski

Not that it couldn't be, but that would be unlikely on the back of a 911. These are the shocks, not struts. Could be the top bearing is worn though. On shocks, it's the spring that puts most of the side load into them and kills the bushings. On the struts, it's the actual side load on the tire that gets them.

J richard

Oops, Matt you're right didn't pay attention, these are rears, not likely. Still that much wear is too much. The tender/shorter spring would be the solution but you may not have the treads left to do it!

Oddjob

I've got the shocks out. Its only happening on one of the shocks, not the other. The bad side shock does not appear to have bad bushing/bearings, but that is only checking by hand. Since they are out, I may send them in for rebuild as a precaution.

Also, the compression of the spring from free length to ride height is about 1.5". So I am a little surprised the spring will buckle/deflect that much under that limited compression range.