[greggers]

Was trying to install my saddlebag brackets on my g5 today, ended up being kind of a pain. As has been noted here before, these bikes don't always have everything lined up. Installing the brackets I got required me to remove the rear shock bolts to fit the mount in directly inside the bolt head. The left side came out and back in quite easily, the right took a bit more coaxing but finally came loose. However at that point, it was clear the fender subframe and the frame mount points didn't line up well at all. I spent the next hour yelling and cursing as I tried to reinsert the bolt. I was close to giving up, took a break, and when I came back 30 minutes later I decided to give it one last try. Somehow in a matter of minutes I had the bolt through. Huzzah! However I'd been at it most of the afternoon at this point, and was hoping to finish up. I didn't have a torque wrench handy. I'd even asked on these boards about torque for those bolts. But rather than go borrow one, I wanted to finish. Classic mistake I suppose. Stripped the threads right out of one of those domed nuts. I suppose it could have been worse, but now I'm out of commission until I can get a replacement  And a torque wrench

[Arizoni]

If I were in your shoes I would remove the thru bolt and take it to my local hardware store to see if I could match it up.

The Ace hardware nearby has a large selection of metric nuts including some that are the matching "acorn" style.
If I couldn't get a acorn nut I would opt for the best grade of regular hex nut they had.
Being somewhat weird, I would get two of the regular hex nuts so that both sides of the bike matched when I was finished.

[prof_stack]

Get some blue threadlocker and you won't have to worry as much about getting the nut on too tight.  Torque wrench is good, if you can get the bit to fit.

[greggers]

+1 for thread locker. Was definitely one of those "trying to force something in a rush that you know better than" moments.

Get some blue threadlocker and you won't have to worry as much about getting the nut on too tight.  Torque wrench is good, if you can get the bit to fit.

[Maturin]

I prefer tooth washers or, for heavy duty, snap rings. Two reasons: the less I´m dealing with chemistry the better and - even more important - these are much cheaper. Using these you can keep an easy wrist when tightening,  just retighten again a little bit after your next ride.
But it´s absolutely clear: as the quality of threads wherever you find them can vary much at a RE, you´ll sometimes will destroy them even with torque wrenches.
There is a German saying for mechanics: after fast comes off - after off comes new