Frozen Rear Brake Caliper Bolt Dilemma

[69Shark]

Hello All,

Does anyone have words of wisdom regarding loosening frozen bolts?

I am attempting to replace the left rear brake caliper. I was able to remove the back caliper mount bolt with a great deal of effort, but the other mount bolt will not come loose.

I've sprayed and soaked the culprit bolt and threads with "PB Blaster" and have been struggling with this for two days. I'm using an impact driver at approx 120 psi. My Vette-owner neighbor suggested that I also use MAP gas or an acetylene torch to heat up the caliper and then strike the caliper with a hammer... and as a final resort to cut the bolt! Not sure how I would go about doing the latter... and it sounds like that option would result in big bucks in repairs (i.e., new trailing arm, etc.).

This resto project is a constant one step forward; three steps back... so ANY help is appreciated.

Thanks!

69Shark

 

[JonM]

You can buy MAP gas in your local Home Depot (plumbing)...comes in a yellow bottle for about 6 bucks. Map Gas burns hotter then propane

 

[69Shark]

You can buy MAP gas in your local Home Depot (plumbing)...comes in a yellow bottle for about 6 bucks. Map Gas burns hotter then propane

Thanks Jon,

I am familiar with both map gas and acetylene -- I was not clear (or comfortable) with the cutting option.

 

[bradfordsvettes]

heat would be your best friend in this situation. you may have to get it pretty hot but it will come. always good with exhaust systems too . keep a fire extinguisher around just in case steve

 

[JonM]

Thanks Jon,

I am familiar with both map gas and acetylene -- I was not clear (or comfortable) with the cutting option.

I don't know if thats a typo...you don't want to cut...just heat

 

[The73vetteman]

I avoid letting gas torches anywhere near my car. Fiberglass is too willing to burn, and the left rear wheel is way too close to the gas tank.

My experience with these things is that PB Blaster is the best there is, but 2 days of soaking isn't that long. Stick at it for a week before getting any more drastic. Also see if you can get any more leverage on the bolt. Those caliper items are supposed to be torqued to about 80 pounds, if memory serves, so they're tight even when not siezed. I slide a 2' length of pipe over the handle of my socket wrench-thing to get enough force to loosen those buggers!

 

[Culprit]

69Shark,

Please don't take this the wrong way, but if I were you I would double check to make sure I was working on the second caliper mounting bolt, and not on one of the bolts that holds the two halves of the calipers together.

The bolts holding the calipers together are torqued a lot higher than the caliper mounting bolts - and would appear frozen if you think you're working on a bolt that should be around 80 ft-lbs. I only mention this because I made that mistake on a different make of car once.

That being said, I vote for PB Blaster, time, a hammer (gently on cast items), and a cheater bar.

Good luck with it.
Semper Fidelis,
Culprit

 

[brusso]

I was thinking the same thing as Culprit. The bolts that hold the caliper halves together are torqued to some rediculous level of torque. When I removed my mounting bolts, I was able to use a combination wrench and a lite ball peen hamer to tap the wrench around. I want to say that the mounting bolts were about 5/8" or 11/16" and the caliper assembly bolts were much larger.

Edit: Oh, if your going to use a torch on something as explosive as thing that contains brake fluid, get some face protection and a flack jacket. Okay that's a little dramatic, it's just not a good idea to heat up brake fluid because it can explode.

 

[GTR1999]

Rear caliper half bolts should be torqued to 60 ft/lbs, fronts are 130 ft/lbs. I believe they are 7/16-20 threads but an impact gun "should" remove them if it's a good one. I have an import gun I used once that has about 250 ft/lb of torque and is total chinese junk.

 

[69Shark]

Thanks for all the responses and recommendations.

Consistent resoaking of the bolt with PB Blaster for three days, some patience, alot of muscle, and a big wrench, the bolt finally came loose! I installed new calipers, rotors amd brake lines - and the car stops on a dime.

Thanks again --- this forum is the greatist!

69Shark

 

[George Black]

69 Shark: You have identified some of the most important items needed to work on C3s: Patience, PB Blaster, Muscle and a Big Wrench!
Always glad to hear of good results. PB Blaster continues to amaze me at times. I have seen it work on bolts when I thought it was hopeless to remove them with a wrench.

 

[75DropTop]

69 Shark: You have identified some of the most important items needed to work on C3s: Patience, PB Blaster, Muscle and a Big Wrench!

LMFAO

 

[Culprit]

Glad to hear you were successful!

Anybody know where I can buy stock in PB Blaster?

 

[KANE]

If you have frozen callipers, whatever you do:
- DON'T ATTEMPT TO THAW THEM IN THE MICROWAVE (no metal in the microwave)
- DON'T ATTEMPT TO THAW THEM IN THE OVEN (they tend to explode when they come in contact with flames)

You would be better off if you placed them in the sink and let them soak in warm water.






I would say you should strike the mounting bolts with a hammer. Then, let them sit for a day or two with penetrating oil. If that doesn't work.... GRIND THE HEADS OFF THE BOLTS!!! Once the caliper is off, the pressure is off the rest of the threads, consequently they come out easier. You may just need to twist the threads out by hand.... or.....get an easy out!!