Caliper Sliding Pin bolt Fused itself to the caliper??

[MaddShadez]

Maybe someone here knows some metallurgy and can explain how this happens. I was removing my brakes and had a seized caliper bolt that just wouldn't budge. Note, the sliding Pin was just fine, it was the bolt that screws into the pin itself that was seized. I took off the caliper and tried the usual tricks with penetrating oils and such to no avail. I eventually used a dremel to cut the top of the bolt off, then the bottom, but the damn thing is still in there? Whats crazy is this part of the caliper isn't even threaded, in theory there should be no reason it doesn't just pop out. It looks like the metal from the bolt has become one with the caliper. I spent hours drilling a hole through it and tried a bolt extractor and it just won't move at all. It looks like I'm going to need a new caliper. Has anyone else seen this?

You can see in the picture the center hole i drilled, and around it the outline of the hole the bolt is supposed to slide through. It's like it was welded or something.

 

[NickT88LSC]

some heat might have worked before you cut it down

 

[pragmatic]

Shouldn't have cut it. I've heated them with propane torch, put the end (with the flat) in a vise and slowly twisted the caliper to remove.

 

[hite337]

Um....just drill the hole out bigger so the bolt fits thru. You already have the pilot hole. Or put your bolt extractor in the hole, use some heat to get whats left of the bolt to spin.

Basically what you have is two dissimilar metals reacting to each other and the environment. They seem welded together but I assure you they are not. No way the caliper could get that hot and still work. The brake fluid would boil first.

 

[Telco]

There is another explanation too. As they are used caliper bolts will distort, pit, expand and go funny shapes, which is normal for the uneven heating plus pressure they see every time the brakes are applied. I've even had one that kinda drooped in the middle causing the caliper to hang. In other words, caliper bolts are a wear item. They should be replaced every time the pads are replaced.

 

[embe]

'Heat treating' can happen unintentionally when stopping/starting a high speed drill bit, then you never regain the rate you had since the drill bit dulls on the part that was overheated and gets duller and the heat rises (repeat). Heat also causes expansion which will make the stub of your bolt a tighter interference fit and it just goes downhill from there. Galvanic corrosion shouldn't be underestimated either, anode vs. cathode =

A new caliper is probably less frustration

 

[cammerfe]

This is the sort of problem that makes me stubborn. If you go back with a slightly larger drill, and then again, since the hole isn't quite on center, you will end up with a piece of bolt on one side of the hole. You'll then be able to use a punch to tap the piece to one side and then get it out.

Massive self satisfaction!!!

KS

 

[MaddShadez]

I forgot to post an update on this, my apologies. I was able to drill that hole all the way through after roughly 2 hours of trying, but with a screw extractor and a large tap wrench it still wouldn't budge. I tried to step up to a larger bit to drill through again, but as you can see in the photo i didn't make it very far until the bit just totally stopped cutting. Another hour of trying got me no where, so I gave up and ordered a new caliper from Rockauto. I agree with Telco, these pins should probably be replaced with each brake job. On the plus side, a clunk i swore was the sway bar bushings must have been from this as it has disappeared completely!

 

[1LoudLS]

yeah with them only being a couple of bucks each, I've started to replace the pins and especially all of the boots each time I do a brake job.