Rear shock mounting bolt stripped.

[Johnhaley]

1982 GS550L. The rear shock mounting bolt has completely stripped. Just found it on a recently purchased bike. Not sure if I’m missing something but it appears to be welded to the frame. I can re-thread it, but I’d rather replace it and keep the stock rounded nut. As far as I can tell it’s welded. It is, right?

[Nessism]

Yes, the stud is welded. There are a number of older threads on this topic where people have performed a variety of different fixes. Some guys thread to a smaller size, some guys chop off the threads and then drill and thread the stud for a bolt. I'm sure there are other options too, including cutting out the damaged part and welding in a new one that's been fabricated with a lathe.

[bwringer]

Drilling the whole thing out so it's a tight fit and then tapping in a 12mm shoulder bolt from the inside of the frame seems to be about the best fix I've seen and done.

I don't remember the length of shoulder bolt needed, but you can get them from (where else?) McMaster-Carr

https://www.mcmaster.com/shoulder-bolts/metric-alloy-steel-shoulder-screws/shoulder-diameter~12-mm

IIRC, a 15/32 drill bit gives a nice snug fit with 12mm. If you can, run a weld bead to secure it and you can grind off most of the head.

The only issue is that you'll need a different nut -- the 10mm threads have a 1.5mm thread pitch instead of the original 1.25mm:

https://www.mcmaster.com/94000A040