Worn Trailing Arm Mount Bolt Hole - Is this common?
 

The mount bolt must have been moving enough to imprint the threads in the edge of the hole. The bolt threads were flattened a little too.

Is this common? What I thought was a worn out mono-ball is looking more like the bolt joint loosened a little, enough for the assembly to move about. This could explain the odd straight-line instability I had. Just a hint of wander, that went away as son as I loaded up the supension in a turn.

http://forums.pelicanparts.com/uploa...1385494783.jpg
http://forums.pelicanparts.com/uploa...1385494796.jpg

Any good way to fix this, short of replacing the mount point? Enlarge the hole and put a sleeve in it? Flanged sleeve?

I saw the WEVO replacement, which would be nice, except the hole would still be a little loose.

Weld some thick washers on the outer part of each mount point and use a longer bolt?

I was thinking similar - weld up about 1-2mm of the elongation, then weld a hardened washer with the correct diameter hole in place on the outside, then use a drill to cut away any excess weld, then use 10mm longer bolts.. but it's easy for me to say.. :D

I looked at some stock washers, and they are not that close of a fit. The best fit was a washer for a 12mm bolt, and the hole would have to be opened up a little. The ther problem was the OD was too small.

So on a hunch, I cleaned up everything, relubed the mono-ball, and reinstalled the trailing arm. Torqued the nut to 72 ft-lb (100 N-m)

Now the joint is tight and all the play is gone. The mono-ball moves freely, with no apparent slop. I looked very closely at the bolt, and there was no sign of distress, other than the wear on the thread.

What is odd, is the washer used was a spring (wave) washer, and does not appear the washer was fully compressed. The marking indicate local contact. Porsche does not call out a spring washer in this location. I'm thinking maybe it is the wrong type for this location.

Anyone know if this is a wave/spring washer: N-011-534-04 PP does not list it.