Since my car is a rally car I decided to swap some washers for NordLock washers at certain parts of the suspension, just as extra security against loosening from the vibrations of driving on dirt.

I was torquing the top rear suspension mount that connects the aluminum end plate of the torque tube to the chassis, when I felt that horrible feeling of the bolt tension go from tightening to loose again. I wasn't even giving it all that much torque yet so I'm thinking maybe it was over torqued previously and this time just took it over the line. Either that or the new washer and Racers Edge aluminum mount spaced the bolt too much and I was torqueing only at the tip of the bolt. These bolts being one of the factory m10 bolts that has the self tapping style slot cut in the tip (what for?).

Now the bolt is stuck and won't back out and I'm at a bit of a loss as to what to do. I'm sure with some fiddling I can get it out but how do I repair the threads? I don't think helicoils are built for that type of load and I'm not sure how much material is inside the chassis for me to step up a bolt size.

Any ideas?

 

Honestly, although Time-serts would be my first choice, a Helicoil would do fine. In fact, it'll be a stronger fastening point than before. Back in auto shop we were given the assignment to test this, and sure enough, it's true. Many years later at work at a research lab all critical fastening points have either Helicoils or Keen-serts as part of new production.

 

the slot cut in the end of the bolt is sort of a thread chaser in case there's any burrs in the nut as the bolt goes in the first time.

thread insert should do fine, or tap that thing to 7/16UNF or M12 coarse.

 

Awesome I'll give the time-serts a shot. I'll measure and pick up some new hardware that doesn't have the slot cut in it and make sure I'm getting proper thread engagement too.

Can anyone verify what the torque for those bolts are? I don't have a haynes but another thread said 52ft-lbs.

 

The torque sounds reasonable for that diameter class 8.8 bolt.

 

I have a feeling that spec you saw was 52 nm. That would be 38 or so ftlbs which is more reasonable for an M10 bolt (and more consistent with other M10s on the car)