Subframe bolt fell out?

[David Conner]

Ted wrote ...
" ... 1990 Audi 100 (non quattro) 
 ... the left rear subframe bolt has fallen out. ...   the replacement bolt
no longer draws tight in the threads."

Ted,
Ooops!
I doubt that it just "fell out".  How long have you owned the car?  I
suspect someone had the subframe off and stripped the threads upon
re-install.  Then they either left the bolt out altogether or else left it
in the stripped threads with not much to hold it in place which led to it
falling out later.  OTOH, if you owned the car since new and know the
subframe has never been off then I have no idea how it could happen.

Yes, I've BTDT...  right rear on an 89 100.   I stripped the threads myself
so there was no big mystery in my case.  The nut that stripped is a captive
nut ... captive inside a body cavity.   There was a cutout opening in the
body that gave me limited access otherwise I would have had to cut a hole
in the body.  I drilled out the captive nut and place a new nut on top the
remains of the drilled out nut.  The standard subframe bolt is long enough
to do this.  I dropped the subframe to do it but I'm not sure it's
absolutely necessary.

HTH,
Dave C.