Removal of seized caliper pistons.

[Neil Spooner]

I am currently restoring my Elan S3 and found both front and rear caliper pistons almost immovable.
I came upon this idea that worked very well.
I cut off a brake hose end that goes in to the banjo fitting at the caliper, drilled it out and tapped it to accept a grease nipple. By using a high pressure grease gun I was able to push out both pistons to their limit by placing a thick piece of steel in the middle of the caliper to arrest the maximum movement of each piston. Warming the caliper helped.

[Craven]

Works well but make sure the cross drilling between the two halves is clear of grease.

[bitsobrits]

An old trick I learned some 50 years ago. It is effective, but does require you do a really effective job of cleaning out the internal passages of all the grease. Note that use of any kind of solvent may compromise the internal O ring between the caliper halves. Probably time for a disassembly and re-plating, with subsequent replacement of the O ring.

[2cams70]

It's a bad idea to use grease unless you plan to split the caliper halves and replace the cross seals. The grease will attack any rubber in the brake system. Normally the cross seals last indefinitively if there's been no mineral oil contamination. A better and easier method is to pump the caliper pistons out naturally on the car before disconnecting the brake lines. By strategically removing and replacing pads one at a time you can direct the hydraulic force to whatever piston you want to force out. Once the pistons are mostly forced out it's usually easy to knock them out the rest of the way once the caliper is unbolted and removed from the car. To knock them out the rest of the way you can knock the caliper on a block of wood on the opposite side to the piston you wish to get out.