At 04:39 AM 4/28/2010, Chris S wrote:
>You may also use a thin flat rubber washer inside that ball joint to
>help keep the mirror in place. If you tighten the nut too much the
>bolt will pull out of the ball joint. The rubber washer adds a bit of
>friction and reduces the amount of required tightening.

On my '84 I bottomed out the spring and pulled the shank out of the
casting; fixed it like Mr. Koerner did but used a roll pin or maybe
the busted shank of an 1/8" drill rather than a dowel pin.  Still had
trouble with the mirrors blowing flat at speed, so I bought a set of
aftermarket replacements from Bus Depot.  Same problem, no cure.  I
worked with them for a while until it occurred to me to disassemble
completely and compare them.  It was obvious that the VW mechanism
was much better than the aftermarket one; I did some fairly obvious
maintenance on the originals -- sorry, can't remember in detail but
it was to the joint itself -- and reinstalled them.  Ten years later,
still no problems whatsoever except that the housing was a bit weathered.

If you have to bottom out the spring, then the joint needs maintenance.

Yours,
David