Thread: Damaged Shock Mount

I've got a '70 KO that I've been tinkering with since last fall. When I bought it was missing nuts and bushings on the lower rear shock mounts and was ridden with the eye of the shock banging on the threads. I've got new bushings installed but can't get the nuts on because of the damaged threads.

Any ideas would be greatly appreciated. Sears has a thread repair tool set. Anyone tried it?

I'm not sure what the sears kit looks like, I have a metric thread file to tuch up the threads. You can get one off of e-bay for around $10. The one I have covers a metric pitch from 0.75 mm up to around 3.0 mm pitch. I don't know the exact pitch on the lower stud if you can't measure it, let me know and I'll double check for you.

Just buy a cheap metric die and run it over the threads. I'm at work now but I think they are 10mm x 1.0

Thanks for the feedback, I'll try to clean it up with a thread file, and if that doesn't take I'll run a die over it.

A photo would be a big help. The best repair method will depend on the type & extent of damage. Anything from file & die work to replacing a damaged stud may be necessary. IMO, since shock mount nuts require a good bit of torque, the less metal removal the better. Solid threads are essential here, no way around it. It may be possible to partially straighten some of the garfed threads using a hammer & screwdriver (or small chisel) before breaking-out the thread file and/or die (used with a generous application of Tap Magic or oil). That extra prep would be my first choice, if it's applicable. For now, we're making reasonable, but blind, guesses. FWIW, I've nothing against using a thread file, it's a useful tool. That said, it works by removing metal and that's cause for concern in a high-torque fastener application.

Makes sense... I'll try to post a picture tomorrow.

This is the best picture I could get. You can sort of see how it's rounded off a bit on the end. I tuned it a bit with a sharp chisel. The nut will now sit square on the stud where it wouldn't before, but still won't turn on. Might have to try "Plan B".

Your photographic skills appear to be more than good enough. How's about a second shot from a 90-degree rotated perspective. That should better show what the threads look like. If the thread damage is limited to the end, as it appears to be, this should be a relatively easy fix. Have to have a little better idea what you've got there before I go rambling on any further.

Thanks, I'll give it a try. The flash was reflecting off the top and giving me a blurry shot.

The thread file isn't really a bad idea, as long as you use the right pitch. It's extremely important to get that right. If you do, then the thread file should only remove material that isn't supposed to be there anyway. Because of the matched pitch, the thread file shouldn't remove any of the good thread.