PBR Brake Piston Sticking

lonestar1 · Dec 23, 2011

Have a 2002 gt and just replaced the front brake rotors and pads. The piston or pistons are sticking on one side. Read in other posts that the PBR's will do that when the piston is forced back in. I've had the caliper off three times now pumping the pistons out and forcing them back in. Still sticks somewhat, a lot better tham before.

Am I going to have to pump the pistons all the way out and put in a new O ring and boot or will the pistons free themselves up. Replaced all brake fluid as I do about every 18 months and greased the pins. Irritating!

Thanks, Lonestar

GDawg · Dec 23, 2011

So, I'm guessing you greased them?

lonestar1 · Dec 23, 2011

GDawg said:
So, I'm guessing you greased them?

Didn't grease the pistons. I've never done that or had to.

Rusty67 · Dec 24, 2011

You may need to take the caliper off the car, disassemble the caliper and hone the cylinder bore. You can pickup a brake cylinder hone at most auto parts stores. Just lube with brake fluid when you hone it out. Clean the cylinder out and use fresh fluid occasionally. Check the cylinder for scoring, if it is too bad then you can replace the caliper body. Also, check the piston for damage as well. As long as the pistons were pushed back in evenly you should be ok.

It is possible you heated up the brake fluid during some hard braking and the fluid became a bit more like glue. If that is the case you will need to hone the cylinder out to clean the varnish out which is causing the sticky piston.

lonestar1 · Dec 24, 2011

Rusty67 said:
You may need to take the caliper off the car, disassemble the caliper and hone the cylinder bore. You can pickup a brake cylinder hone at most auto parts stores. Just lube with brake fluid when you hone it out. Clean the cylinder out and use fresh fluid occasionally. Check the cylinder for scoring, if it is too bad then you can replace the caliper body. Also, check the piston for damage as well. As long as the pistons were pushed back in evenly you should be ok.

It is possible you heated up the brake fluid during some hard braking and the fluid became a bit more like glue. If that is the case you will need to hone the cylinder out to clean the varnish out which is causing the sticky piston.

Didn't have any problem until I pushed the pistons in to clear the new pads. The old pads/pistons released just fine, could easily spin the tire with no binding. Haven't done any canyon driving particularly in Houston so fluid should have been OK. All new fluid replaced with the new pads and rotors and it was barely discolored. I haven't had to hone a wheel cylinder since drum brakes.

Rusty67 · Dec 24, 2011

What tool did you use to press the pistons back in ?

lonestar1 · Dec 25, 2011

Rusty67 said:
What tool did you use to press the pistons back in ?

Used a "C" clamp and a paint brush handle actually to span the piston. Pushed each one in individually. Mustang is the first vehicle I've had with dual pistons.

Lonestar

Rusty67 · Dec 25, 2011

Did you crack the bleeder valve on the caliper when you did it ? You bled the system after you pushed the pistons back in not before right ?

lonestar1 · Dec 26, 2011

Rusty67 said:
Did you crack the bleeder valve on the caliper when you did it ? You bled the system after you pushed the pistons back in not before right ?

I didn't crack the bleeder valve when pushing the pistons back in. I always bleed as the last thing with brakes. I've probably put about a pint through this caliper, wife is tired of the garage work on the pedel.
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