Broken Wheel Bolts

[Dan Cordon]

Kneale wrote:
> Anybody faced this before:
> http://www.pbase.com/kneale_brownson/image/39122017  Those holes you can't
> see through have broken-off ends of wheel bolts in them.   The broken bolts
> are at    http://www.pbase.com/kneale_brownson/image/39121870

Bummer Kneale! There's many ways to extract broken bolts. Some are 
better than others, but they all depend on what you have available.

You mentioned screw extractors. Those may be okay, and the larger the 
better. You don't have to be super precise about being on center, but if 
you end up drilling/tapping, you'd be happier if you were. If you have 
access to some heat (even a propane torch), do heat the area around the 
threads to help it expand.

Also, (I'm not looking at my car now, so I could be wrong) you should 
have the option to thread the bolts through the hub (as opposed to 
pulling them out the way they came in). I don't know if either will have 
an advantage in this case.

Other options may be:
If there's enough thread exposed on the back, locktite a nut (correct 
thread diameter and pitch) on the back side and use that to thread through.

Weld a nut to the center of the stud, and use a regular wrench to pull 
it out.

Use an impact screwdriver to help break it loose.

Pull the hub off and find a replacement (expensive, but you can replace 
the bearing while you're there...)

I'm sure there's more options as well.

As to why they broke....I don't know. Actually, looking at the failure, 
it appears that there's a fair amount of material that was broken (rust 
colored) prior to the final break (clean part). It looks like a crack 
started some time ago, and has been propagating inward. Perhaps 5 years 
ago they were torqued (or untorqued) pretty harshly?

Still, there was a lot of material left on the clean break surface. 
Probably had to hit some pot hole (or equivalent) pretty well to break 
the remaining area. Perhaps it may not be a bad idea to inspect the 
other bolts and replace any that seem questionable.

Wish I had more useful info to share-

-- 
Dan Cordon
Mechanical Engineer
University of Idaho - Engine Research Facility





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