Help! Broken Bolt Removal??

[Donne Trav]

Well, I broke a bolt off replacing one the calipers.

What's the best/easiest way to remove the bolt.
It looks to be about 2 1/2" long with threads being
about 3/4 to 1". So most of the bolt fell out with
some of threaded end remaining, Thanks

 

[gmjunkie]

Well, I broke a bolt off replacing one the calipers.

What's the best/easiest way to remove the bolt.
It looks to be about 2 1/2" long with threads being
about 3/4 to 1". So most of the bolt fell out with
some of threaded end remaining, Thanks

Is it one of the bolts holding the bracket to the steering knuckle??
Got any good photos,If I can see it I may be able to help!

 

[Hib Halverson]

A bolt that's 3/4-1-in in dia can only be the bolt which holds the caliper mounting bracket to the steering knuckle.

OMG...breaking that bolt would be hard to do.

It's going to break because either it's bottomed in the hole (unlikely) or because the bolt threads seized.

The Junkie may have another idea but, if this was my problem, I'd remove the knuckle, take it to a machine shop and have them set it up on a mill then drill most of the old bolt out, then see if the remainder can be removed somehow. If the remainder cannot be extracted without destroying the very soft threads in the aluminum hole, you may be buying a knuckle.

One problem is the bolts holding the bracket to the knuckle are really hard. The bolt is obviously really big, too, so the problem may be such that trying to drill into that bolt with a hand drill will be a lost cause.

One might think you could heat the knuckle then get what's left of the bolt out but...will that destroy the aluminum's heat treating? If so, maybe that's not such a good idea with a steering knuckle.

I'll be interested to hear what Junk has to say.

 

[tankman]

Been a while since I've done brakes on a c4, but as I recall the only screws even close to that would be the ones that mount the caliper mounting bracket to the knuckle. If memory serves, it's the bracket that's threaded. Assuming that is correct, and the other mounting screw has been removed, the bracket is free and clear, off the car. Luckily the place where your bolt broke off is a thru hole. This way you can drill from the back side and with any luck the motion of the drill will remove the screw. Upon attempting this its important to start in the dead center of the screw. Even if you don't remove the screw with the drill, it will make a nice pilot for an ez out.
Considering those screws are generally hardened, a quality drill is imparitive. Even a grade 8 screw can be drilled with the correct equipment.

As junk says though, pics would be great!!!

good luck
Tank.

 

[93Rubie]

The bolt has to be broken off in the caliper bracket. That is the only part that is threaded and has a larger bolt. You must have worse luck than me, I've taken literally hundreds if not thousands of those out with a problem. In a salt state with lots of junk on the roads.

Yeah, stuff can be drilled but...HSS and the like are worthless. Cobalt bits, slow, and patient. If you get a drill/mill close to the hole size and they have a tap big enough, you might be able to save it. Drill as much out as you can w/o taking the remaining threads in the knuckle then tap it. CAREFULLY, you WILL NOT drill a tap out. If the tap breaks, your kinda pretty much screwed. They are very hard and very brittle. Go slow.

If in doubt........oxyacetylene torches. I've never had something I couldn't get off. How nice and clean stuff is afterwards is another story.

 

[Robertwav1]

Well, I broke a bolt off replacing one the calipers.

What's the best/easiest way to remove the bolt.
It looks to be about 2 1/2" long with threads being
about 3/4 to 1". So most of the bolt fell out with
some of threaded end remaining, Thanks

Broke one on my truck once. Drill and EZ out as recommended. Advance auto had a replacement bolt for the caliper that had a slightly larger thread and self tapping. I guess this happens quite often. Another option if the thread gets f'd up when trying to remove the balance of bolt...heli-coil thread insert. Ask me how I know. I believe it was an 8mm kit.