2 Strokes Down Under

I've got a stuck caliper piston. I've tried 100psi of air pressure and zilch.

I now have it soaking in WD40 before the hydraulic pressure treatment.

Before applying the hydraulic pressure treatment I was thinking of putting the caliper in the freezer to chill everything including the alloy body and the steel piston and then heating the alloy with the heat gun immediately before the hydraulic pressure treatment.

The different expansion rates should help to crack the seizure shouldn't it?

Ive never found a piston that didnt shift with a master cyl connected to it and then play a heatgun over the caliper. works for even the nastiest (and ive had some beauts) of calipers...

Yes that should work.

Other option is to heat the whole lot, then spray the pistons with some freezing spray.

honestly.... Ive never needed to freeze any, even with really badly rusted pistons and oxidised bores and ripped and bulging seals... just sayin.

Me either... but just sharing the options.

A compressor is not the best option, because 100PSI is really nothing as far as brakes are concerned.

As usual Jeff, we are in agreement. Ive never found a compressor, let alone a foot pump to be any use with brakes, and lets face it if (when) it comes out the volume of air will send the piston off like a missle, denting that freshly painted tank on the bike you parked the other side of the shed, or taking your mates eye out... not ideal on a wet wednesday in Warrington, let alone in Sunny Sydney.

I use a usable but grubby 5/8 front master cylinder and a bit of old 7/8 bar clamped in my vice. With the master connected and some fluid pulled thru with a bleeder (or syringe) it will be bled enough to get you going, if not play the heat over it and soon it will move. Two people helps as well. One to work the brake lever and one to do the heat and mess with the piston.

But... if it takes this much work then the seals, piston(s) and maybe the caliper body will be trashed anyway. few come back from this amount of neglect.

If you use normal pliers you will kill the pistons... probably not a problem, they are obviously rusty anyway. using the internal special brake ones will brankrupt you tho. If anyone knows of a cheap set id be interested.

I've never seen a compressor work either, and I'm with the rest of you, pump it the master cylinder.

It off the LC - twin disc. One popped with air; the other didn't.

The reason I used air was because the the hydraulic wouldn't pump up, because the caliper was leaking, which is why they are being pulled apart.

Now I might also have a prob with the master cylinder which is why I'll use the rear master of my GTR1000 as the master. Either way I still sus it is going to be 'an issue' which is why I'm going belt and braces with the prep.

hmm, well you will have to pull it if you can get pliers on it then. usually even leaking they pop out with heat.

Done

Cool... and, which method?

JonW wrote:Cool... and, which method?

Freezer, heat gun, GTR rear brake master cylinder

High steady sustained pressure to start with, once it popped just kept pumping the rear brake.

Now I have to figure out how did it get this way.

Jon, check your PM.

it got that way thru neglect...

er, no PM...

JonW wrote:it got that way thru neglect...

er, no PM...

The other one is perfect - same bike, same resto, same storage.

PM take two sent.

such is the life of brakes... dirt/salt/water... it all makes its way under the seals and stays there

PM recd!