Brake Calipers

[65_BRG_Sprite]

Froggy has been sitting for 10 years and I'm getting close to completing a full restoration. I started on the front brakes this morning, I believe the pistons have seized on the dry seals and do not want to 'pop out. By removing the hose I could use that aperature to gently persuade the piston out. The other side has no such access. 135 psi air has no effect. The pistons that I've removed are shiny and smooth and the bores look great. Any ideas to remove the two holdouts? And yes new or rebuilt calipers would be nice but unaffordable- that's why I'm 10 years into a planned 2 year restoration. It has been a lot of fun though! I've learned to weld, to paint, and patience.

 

[Jim_Gruber]

So what have you tried soaking the caliper in.

 

[65_BRG_Sprite]

Been shooting/soaking it with PB Blaster, next thought was soaking it in mineral spirits over night.

 

[nomad]

If you can fit a grease zerk a grease gun will push anything out!
Barring that you can try driving the piston in a bit to break it loose then apply the air for a little exitement! Also a special plier that fits on the inside of the piston that you may be able to use to turn it and break it loose. Pay close attention to where the cutaway's on the pistons are when you reassemble.

Kurt

 

[HealeyRick]

Replace the removed piston and hold it in place with a c-clamp. Use a lever-arm grease gun to inject grease through the brake bleeder hole. You may be able to screw a zerk fitting in the hole to make it easier. The hydraulic pressure should pop it out.

 

[65_BRG_Sprite]

Will give it a shot first thing in the morning.

 

[65_BRG_Sprite]

Soaking and healthy dose of grease did the trick- thanks. Cut-aways on the pistons?

 

[Jim_Gruber]

I seem to recall they go down but better get another answer here.

 

[65_BRG_Sprite]

I'm obviously missing something.... one piston on each side was dished slightly on the inside at bottom, but they were not uniform side to side as inside/outside position in the caliper. Previous owner's error?

 

[Jim_Gruber]

Back to the top on this one. Dish on caliper pistons, which one goes where Inside/Outside of caliper and I seem to recall Dish being on the bottom.

 

[PeterC]

Yes..... the cut out should be on the leading edge as the rotor rotates. It allows the pads to tilt a little as noise reduction. Not critical to the operation.

Peter

 

[Jim_Gruber]

See I knew someone would have the right answer. Thanks Peter.

 

[Gerard]

The cutaway portion of the piston should be facing downwards.

 

[nomad]

Not quite sure what you are calling a "dish". The piston's where they contact the pads will have a side that is milled a little shorter than the other. The milled away section should face the direction of rotation of the disc when slowing down or, in other words, aproximatly down. If they are not that way you will have trouble with the brakes binding and generally being a headache. I learned the hard way!!

Kurt.

 

[65_BRG_Sprite]

Ah-so! Now I'm understanding, thanks.