I am in the process of changing the brake pads on my 87 4-Runner. It has the S12+12 calipers (4WD IFS 4-piston). I got the driver's side completed so far. However, the top front piston on the passenger's side will not go back into the caliper. It moved in only a fraction of an inch and will not move any further. The other 3 went in fine. I tried removing brake fluid from the system and then tried taking the caliper off and using a C-clamp however that did not work either. I pulled the cylinder boot and set ring and tried to remove the piston but I can't figure out a good way to pull it out. Any information on this subject would be greatly appreciated. Anyone have any experience rebuilding these calipers? This happen to anyone else? I need this thing back on the road by tomorrow.

Got an air compressor? I rebuilt my 88's brakes this last winter and I used air to force the pistons from the bores. When it was down to just one being stuck...things got interesting- but with some penetrant and about 100 PSI and the other pistons clamped inplace it finally came out.

I'll never buy a caliper again after realizing how easy they are to rebuild. Only about $8 per kit available at almost all parts stores.

Watch your fingers when doing this...broken finger tips hurt!

~Darin <img src="/forums/images/graemlins/baby.gif" alt="" />

do you just hook up the air where the brake line connects?

Yea, use air pressure, but put something soft in the caliper where the piston is going to be fired into so you don't damage it. Whenever I've done this in the past I've just popped them out with hydraulic pressure. You probably have that piston slightly cocked in the bore, hopefully you didn't groove it.POC <img src="/forums/images/graemlins/patriot.gif" alt="" />