Here's a potentially VERY BAD thing that can happen if those bolts get loose.
 I know because it happened to me.  This was on my '73 Westy (I don't know
what years/models could potentially be affected by this problem, but check
yours out.  On my bus, two of the bolts on the left CV had come loose.  One
of them eventually fell out leaving the locking plate free to move around on
the other bolt.  The locking plate actually cut through the brake line and I
had no brakes!  Luckily it happened as I was pulling into my driveway which
is at a slight incline and I stopped before driving through my house, but it
could just as easily happen driving down some huge hill.  I can't believe
they routed the brake lines that close to the CV's!  I check my bolts very
often now because I want to make damn sure that never happens again.  When it
happened, I raplaced all the bolts and all of the locking plates and used
thread lock and torqued the bolts to about 5 ft-lbs. above spec.  I haven't
had any problems since.  Check yours and make sure they are cool.  It could
save your life.

Sean Stueber
'63 Kombi
'73 Westy