Inner brake Piston in Caliper is concave

Hi I have a weird one here I am rebuilding front brake caliper and was removing the pistons I have the easy one out but the rear piston is concave actually appears to be bent in the middle inward. I have tried to blow it out with compressed air but it wont budge. has anyone ever seen this before. Mystified Drummer99

A bit late to the party but you could restrain the outer piston and pump the inner out with the master cylinder worst case. (I had to do that with one piston on a Brembo P4 last year)

I put the stainless (RGM ?) pistons in with threaded internal bosses for the next person to do in 2061.

Drummer99 said:

Hi I have a weird one here I am rebuilding front brake caliper and was removing the pistons I have the easy one out but the rear piston is concave actually appears to be bent in the middle inward. I have tried to blow it out with compressed air but it wont budge. has anyone ever seen this before. Mystified Drummer99

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A few options:

Get a nice thick suede glove on, then heat the caliper up and repeatedly smack it down on a piece of wood laid on a solid floor.

Carefully drill through the centre of the piston, then tap a thread in it and screw in a bolt which should force the piston outwards.

Buy some brake piston pliers like these which will enable you to get a purchase on it and twist it out.

I always dribble brake fluid around the piston as it helps release the seal once it's moved.

If it is really distorted for whatever reason I doubt it will come out. A picture or two would help though.

Hope that helps,

cliffa

Can't see them ever distorting , but all of the above , order in new seals and S/S pistons whilst you work on the remaining piston. Work clean on this .

probably some one stood in front of a lathe like I used to do....$50 labor to make a $10 part. Mine looked good and worked good. Stainless not rusty chrome
Lookie here...for disassembly
caliper

Drummer99 said:

Hi I have a weird one here I am rebuilding front brake caliper and was removing the pistons I have the easy one out but the rear piston is concave actually appears to be bent in the middle inward. I have tried to blow it out with compressed air but it wont budge. has anyone ever seen this before. Mystified Drummer99

Click to expand...

Picture please.