Front subframe threads stripped out.

[BN00249]

Appears as though someone possibly cross threaded one of the front subframe bolts. Drivers side I would hear a clunk when braking hard or upon acceleration. I went and tightened bolts. 1 was not quite tight and the other one when I tightened ended up just pulling threads out. I’m referring to the bolts that bolt the subframe to the actual body of the vehicle.
So my question is, what’s the best plan of attack? Drill and tap oversized to M14, timesert, helicoil, or the worst of all cutting a small hole and put a nut on the backside of that bolt..?

[BuddySpeed3]

Originally Posted by BN00249 Appears as though someone possibly cross threaded one of the front subframe bolts. Drivers side I would hear a clunk when braking hard or upon acceleration. I went and tightened bolts. 1 was not quite tight and the other one when I tightened ended up just pulling threads out. I’m referring to the bolts that bolt the subframe to the actual body of the vehicle. So my question is, what’s the best plan of attack? Drill and tap oversized to M14, timesert, helicoil, or the worst of all cutting a small hole and put a nut on the backside of that bolt..?

Try re-tapping with the same size first. If that doesn't work go a bit bigger with a helicoil. That's a pretty crappy situation though. Is it possible to gain easy access to the top of the hole and use a nut on the top side?

[BN00249]

I think I’m going to helicoil it and jb weld the helicoil in place. I don’t have correct pitch tap as it’s m12x1.25 and finest I have is 1.5. But for sure there’s not much point in trying.
There’s no access behind unless I’m cutting a hole into unibody frame rail. I found a pic of which one I’m talking about. Luckily other 2 are holding very strongly.




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[PlatinumCore16]

We use helicoils in our shock and vibe lab. I'm not sure they use adhesive though.

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[GroceryGtr]

no need for adhesive on helicoils. that being said a small access hole in the body to get a nut in there won't be the end of the world. Cut it on 3 sides and fold it out of the way. When you're done touch up the edges with paint/under coating, bend the flap back in place and use some black rtv to seal it back up.