deltawedge

After pushing the pistons back into the calipers to change pads, the outboard set of pistons (front left) will not extend when the brake pedal is depressed (only the inboard pistons move). Needless to say, I'm a bit stuck. Anyone encountered this and what was the solution? Thanks.

kkim

If you have really pumped/stood on the brakes with the engine running and the pistons still won't move, I'd say that the inside of the caliper is most likely rusted/corroded from water and the pistons are seized in the bore. I had this happen to me on another car. I disassembled the caliper, cleaned out the rust and gunk, sanded the rusted parts a bit, then reassembled everything and it still works great to this day.

Another thought... have you tried flushing the fluid recently?

Totally unrelated to your problem, but since you're working on the brakes... water cleans up brake fluid really well.

deltawedge

Is it possible to push the piston too far back into the caliper? I did a flush at the same time, and there was a significant amout of water in the fluid (cloudy looking but not dirty). I'm going to try to extract the piston as mine first plan of attack.

viperbob

Ge careful when removing the pistons. I use some small pieces of wood between the sides of the pistons. Then a little compressed air (small blow gun with rubber neck) in the inlet to the caliper. DO NOT GET YOUR FINGERS ANYWHERE NEAR THE PISTONS, and use glasses as there will be some spurting brake fluid. It just take a small amount of air to push out the pistons so go SLOW. If the far side does not come out, remove the cross tube and use the compressed air on that side. Simple huh? I have seen the remnants of pistons removed with pliers and such. Not a pretty site. If you have to do it this way, be REALLY careful, use rags to protect the pistons. Any scratches and you can have a leaky piston.

deltawedge

How about using a battery terminal spreader pliers with some rubber hose to fill the gap on the inside diameter of the pistons and pull them out? Is there a good chance of breaking the pistons? What material are the pistons made of?

Thanks.

kris

I suppose the pistons are the same as on my 964, they are some kind of hard plastic. I renewed all 8 pistons and seals on mine last month because of a similar problem. No visual damage to the pistons was noticed but the seals were worn. Pretty easy job to do, I used air pressure to pop out he pistons. I blew the air in via the entry for the copper tube while sealing off the other openings with a large piece of cloth. The sets (Brembo) are quite expensive. Make sure to give everything a good cleaning while you're in there.Just like Bob said be very careful with your fingers, use plent of protection.Better safe than sorry.