Heated frozen brake pucks -- Uh Oh

[RossKean]

If it was my braking system, I would be verifying things with precision measurements. Your brakes, your call.

If it was your braking system, I expect that you wouldn't have used a torch in the first place.
Anyone else share my recollection that one (or both) piston pair(s) in the right caliper are a distinctly different color than pistons in the left one?

 

[torch]

If it was your braking system, I expect that you wouldn't have used a torch in the first place.

Touche.

Although neither did the OP. IIRC, he did it in the second or possibly third place. There was mention of an ultrasonic cleaner and penetrating oil.

But before resorting to heat, I would have tried the old grease gun trick at least. Fabri-cobble an adapter and use a grease gun to pop the stuck pistons out. You do have to clean the grease out afterwards, but then if the piston(s) are that stuck, things probably needed a good clean anyway.

 

[Whooshka]

OP hasn't been back since he made this post days ago.

 

[RossKean]

OP hasn't been back since he made this post days ago.

Same individual posted over at FJRowners and hasn't participated in that discussion either.
https://www.fjrowners.com/threads/heated-frozen-brake-pucks-whuh.160439/

 

[Fred W]

I know it doesn’t apply directly to the OP’s question, but I had the “opportunity” to work on a friend’s FJR front calipers that were completely seized. In his case it was caused by the seals having become swollen, most likely from being sprayed with fork oil when his fork seals leaked previously. The swollen seals got jammed between the bores and pistons and would not budge.

Managed to get them out using compressed air. After one of the pistons blew out, I stuck it back in its bore without a seal, and using old brake pads and sockets, rigged up spacers to retain the 3 pistons that I wasn’t blowing out, if that makes sense. 100 psi was enough to get them all out eventually. No heat required.

All he needed was new seals. And for the record, never put any oil or grease on brake seals. Pure silicone grease might be ok, but I would stick with brake fluid for assembly lubricant.

 

[torch]

You gotta use what you have available. That said, compressed air tends to release violently (witness "one of the pistons blew out") compared to an incompressible medium (such as grease). Extra precautions (enclosure, safety glasses, etc.) are warranted to prevent injury.

 

[Fred W]

When they “blew out” it’s because I was “blowing in”. There was nothing explosive. As each piston blew out there was a little pop and it hit the opposite side of the caliper. I wrapped the caliper in a rag mostly to prevent being sprayed by residual brake fluid.

Not sure how you’d ever get enough pressure out of a grease gun to push the pistons out. And then how would you get all that grease out of the inside of the caliper? Because you really, really don’t want any grease inside your calipers.

Brake fluid would be better, but just for the first piston, and even that makes a huge mess.

 

[Panman]

Air and a little thought works for me.

 

[torch]

When they “blew out” it’s because I was “blowing in”. There was nothing explosive. As each piston blew out there was a little pop and it hit the opposite side of the caliper. I wrapped the caliper in a rag mostly to prevent being sprayed by residual brake fluid.

Not sure how you’d ever get enough pressure out of a grease gun to push the pistons out. And then how would you get all that grease out of the inside of the caliper? Because you really, really don’t want any grease inside your calipers.

Brake fluid would be better, but just for the first piston, and even that makes a huge mess.

Sorry, I had envisaged a hard-piped connection. Still, some precautions such as safety glasses are probably warranted. I had a friend lose half the skin on his face under similar circumstances. When things let go, dirt inside acted like a sandblaster.

A grease gun can easily generate a couple of hundred psi (when hard-piped). Yes, the grease needs to be cleaned out afterwards, but that's probably a good idea anyway. A caliper in that seized condition is probably full of spooge to begin with.