Stripped bolt threads in steering knuckle?

Basically was trying to remove the brake caliper to replace my rotors, and when I took out one of the two bolts that keep the rotors in place, the thread got striped.

Would a thread repair kit be able to take care of this? I am pretty scared of drilling into it worried I’ll just make it FUBAR. Wondering if anyone else has had to do this.

 

Helicoil kit will work. How did that strip though?

 

Always make sure to hand thread a few turns before just going HAM on the impact.

Can you run the bolt in from the other direction to straighten out the threads? Looks like it could still have come good engagement further in.

That's a pretty bad place to mess threads up. Can try using a Helicoil as the other poster said, but sounds like it might be a good time to grab those boxed knuckles you know you've been wanting

 

Really not sure. I didn’t use an impact to remove anything. Had to use a breaker bar

 

What's the factory torque recommendation? That's one of the bolts holding the caliper? Not sure I want helicoils there.

Only used a helicoil once. A lot depends on how much original thread is left for it to bite into.

 

A brake calipers bolt stress is in shear while braking the forces are trying to break the bolt is two (vs pulling the threads out). Brake caliper bolts aren't typically high torque either compared to something like a head bolt (which are in tension).

I would not be worried about repairing it with a helicoil as long as any replacement bolt is the same strength as the original bolt.

 

You don't need threads left, you drill it oversize, tap oversize, install helicoil.

Done right you're better than new and good to go with a helicoil or other thread repair. I'd get the kit and do it. Good news is a whole replacement upright isn't hard to come by if you screw up.

 

Out of safety concern and since you asked I would recommend replacing the whole knuckle/spindle. Might seem overboard, but if that bolt ever walks out or comes loose you are asking for trouble.

 

Weird. I can't say I have ever heard of those holes stripping before. Usually it's aluminum you need to worry about not cast iron.

A word of advice though. When removing bolts an impact is less likey to strip threads than a breaker bar. Like drizzoh said it's really easy to strip threads if an impact is used to start a bolt.

 

In all actuality, the Helicoil is a stronger thread than the cast iron. However, if there was an accident, because of failure of that steering knuckle, the Helicoil just made it a modified part.....not good in a legal battle. I am sure that most any reputable shop would tell you same .

Replace the knuckle, have peace of mind.

 

You don’t use any original threads with a helicoil… it’s drilled out then new threads are cut and the coil is threaded in. The ID of the insert is the nominal size of the original bolt.

Plus brake caliper bolts are under shear strength not tension, so a helicoil done properly is perfectly acceptable repair

 

Machinist here for 50 years, Helicoils are actually a stronger thread, however you aren't considering the fact that the original hole has been enlarged diminishing the cross sectional thickness, potential for something breaking.
Plus, it is against the law for shops to alter Steering and Brake components.
If there's an accident, for whatever reason, that points back to that modification, you're in trouble.
Nuff said.

 

i doubt there's much force on those threads if it's just to hold the rotor in position. isn't that what the spindle threads on the hub do anyway?