Removing a Stuck Caliper Piston


by Vic Whitmore and Carter Shore

Jeff McNeal wrote:

One of the pistons is stuck and I can't seem to get it dislodged from the cylinder no matter what I try.

Jeff, you have two options to get the piston out.

If you have compressed air, you can hook it up an blow out the piston. Do this with considerable caution because the pressure can build up significantly and when the piston frees up, it will shoot out of the cylinder. Place a rag around the caliper opening to catch the piston.

The safer alternative is much messier. Fine a grease nipple that fits the caliper threads and screw it in finger tight ( so as not to distort any of the threads or damage the seat). Pump the caliper full of grease and the piston will be forced out. Since the grease isn't compressible, only the trapped air inside compresses and the piston just pops out with little force.

Go for it!

Vic Whitmore
vicwhit@home.com

Here's another (messy) way to extract the piston from the caliper:

Connect it back up to the hydraulic system (loose, not mounted), wrap it in towels, and push/pump down on the brake pedal.

This will create about 1000-1500 psi (the design working pressure of the brake system), and pop the piston out.

If the piston will not come out this way, you can pretty much forget it.

Have you already removed all the other brake components? No problem as long as the clutch master cylinder is still mounted:

1) Unscrew the fitting where the metal clutch line connects to the MC, bend it slightly out of the way.

2) Screw the caliper flex hose end into the hole in the MC where the clutch pipe was. They are both 5/16-24 threads. Of course, be careful not to bugger the threads, be CLEAN, and do not overtighten.

3) Thread the other end of the flex hose into the caliper.

Proceed as above, wrap caliper, push/pump clutch pedal, etc. You may have to add more brake fluid to the resevoir.

Good Luck!

Carter Shore
clshore@yahoo.com

baddogracin@gmail.com


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