Mangled threads on Rear lower shock mount.

[kelkins]

I have no idea why this happened, but the first 3 or so threads on my passenger side rear lower shock mount are absolutely buggered. The bolt will thread in a bit, then stops dead in its tracks. The rest of the threads look just fine, and the bolt looks fine, except for the very end of the bolt. The bolt came out fine, but will not go back in. Very odd.

I'm thinking that running an M12x1.25 tap through the hole should clean things up enough. What should I do if that doesn't work? I would rather not drill it out for a larger bolt since only the first 3-4 threads are buggered.

Suggestions? I do have a torque wrench and the bolt was previously torqued to spec at 75 ft/lbs.

 

[jk24runner]

You could try notching a little on the tip if the bolt like cut a line down the middle 3 or 4 threads and pinch it together a bit.

 

[kelkins]

You could try notching a little on the tip if the bolt like cut a line down the middle 3 or 4 threads and pinch it together a bit.

Ah, the poor man's tap. The shock bolt already has one small notch in it. I have seen several videos of this type of fix, and it seems to work well. Unfortunately, I don't have all of the tools needed to try this.

The bolt will thread in a few turns, then it starts going sideways. I'm hoping a proper tap will fix the issue. Of course, no one has the correct tap in stock, so I am waiting for Amazon to drop one off this Sunday.

 

[fkheath]

Ah, the poor man's tap. The shock bolt already has one small notch in it. I have seen several videos of this type of fix, and it seems to work well. Unfortunately, I don't have all of the tools needed to try this.

The bolt will thread in a few turns, then it starts going sideways. I'm hoping a proper tap will fix the issue. Of course, no one has the correct tap in stock, so I am waiting for Amazon to drop one off this Sunday.

Since the end of the bolt is buggard, you should replace it with new or clean it up with a die.

Also, when you use a tap to clean up the threads, can you start it from the back side? That would insure a clean start.

If all that fails, you may need to renew the threads with a TimeSert; ++ TIME-SERT Official Threaded inserts for stripped threads, blown out sparkplugs, Be sure to use a TimeSert and not a helicoil which is inferior.

 

[kelkins]

Problem solved.

The bolt was pretty bad at the very end, so I cleaned up the threads with a 12mmx1.25 die. The die essentially removed the final 2 threads form the bolt, which is fine given the length of the bolt. This was the most difficult part of the fix. The damaged threads are not sheared off, but are shorter than the remaining threads.

I then ran a 12mmx1.25 tap through the lower shock mount. This worked very well, given the state of the final 3 threads.

The bolt when in just fine using hand pressure, and torqued to spec (72 foot pounds) without issue.

I hope this helps someone in the future, as most threads had solutions involving drilling the hole, tapping to a larger size (14mm - Good luck finding a bolt that works in that size), or installing an insert. If you have just a few damaged threads, chasing the threads should work for you.