Installing Light Bar - Bumper mount bolt threads marred

I'm installing a light bar purchased from Pelley, and while removing the nuts holding the bumper on, I guess I marred up the threads because the nut will not go back on. The nut will catch for about 1/2 turn, then slip off when I try to tighten it. Anyone have suggestions how to clean up the beginning threads a little without removing the light bar bracket? It will be a big PITA if I have to remove everything to run a die over the bolt, so I'm hoping that's not my only answer. A ratcheting wrench will barely fit over the nut with this bracket installed.

 

I can think of a few ideas, but they both require you to remove the bracket. Can you post a pic or two so I can see what you are working with exactly. I think I understand, but want to confirm!

The right thing to do it yes, run a die over it to clean up the threads. There is not a lot of room in there, so you will probably have to take off the bracket.

The other option I can think of, is to try and get in there with a file and clean up the threads by hand. You might be able to do this with the bracket still in place depanding on where the threads are goofed up...

 

Here's the best picture I could get...you can kind of see the first few threads look a little messed up

 

Get a thread file and clean them up.

 

I agree, a small triangle file or something similar should do the job, if not, bad news is the die...