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Old 09-05-2017, 07:21 PM   #7
jakeru
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Join Date: May 2015
Location: Greater Seattle, WA
Posts: 534
Thanks for the words of encouragement and appreciation, 78f350, Deserion, and nine8six! I hope this is useful to other forum members who are considering doing repairs & improvements themselves.

Anker - I also appreciate you weighing in, but must respectfully disagree about sharing your personal opinion that this repair "doesn't make sense", and your assertion that the "forces are so great" [that] "it won't hold".

Obviously, the forces are pushing the limit (if only, by just a a bit!) on what "new" design bearing would hold, or otherwise the factory joint wouldn't have developed any slop, even the small amount I observed in my joints (I'd guesstimate only one of my two 120k miles joints had only about .005"-.010" play - althogh it is enough to hear going over pavement joints in the cabin of the car).

However, the likely weakest material involved in these joint is the white plastic balljoint liner, which is probably teflon (PTFE) or something similar, used for reduced friction.

Teflon-lined aftermarket spherical bearings or "heim joints" are readily available for applications like camber plates, as are metal-on-metal spherical bearings, which give more static friction AKA "stiction" than the teflon-lined variety. The teflon-lined spherical bearings generally need more surface area (larger dimensions) to deal with the same load as a metal-on-metal joint. So, I'll bet it's the plastic liner that's first piece to deform in these Porsche 986 joints...

Anyhow, I think it most likely that the factory teflon liner probably got pounded a bit (.005"+ very plausible compression, as given the piece is probably .065" or so thick, that's only ~10%+ thickness reduction) after this sort of high miles, 100k+ mile use. Even if the aluminum housing gets pounded, forced a bit more into a shape which conforms with the inner metal spherical bearing, I'd surmise that rebuilding in the way I describe (by tightening up a "seasoned" or "broken in" joint like this evenly, while also ensuring the lubrication and sealing from the outside elements is "as good or better than new"), stands more of a chance for going longer than the original design ~100k than simply buying a "new", unseasoned, not broken in plastic-lined joint, and simply replacing with that. That's because the softer surfaces which get deformed in use, after being brought closer together after being "broken in", may then be more resilient against further deformation or wear.

But then again, that's just my theory. If a new joint lasting only another ~100k is good enough for your needs, the several hundred $ parts cost doesn't matter, you or your mechanic aren't required with necessary equipment or skill to repair (which I attempt to help you decide and facilitate by detailing here), then by all means, replacing with new is probably your best bet. Hope that information helps!
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Last edited by jakeru; 09-05-2017 at 09:30 PM.
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