Hey All

Trying to replace the rotors and pads on my 2nd gen. Front are done, no major issues.

But having a big issues with the rear passenger side. Can't push the piston back down into the caliper so it will fit over the new pads.

The fronts i could either push down with my hands or use some adjustable hand grips. The rear drivers i did have to resort to a clamp but it went down fairly easy once i got the clamp on it.

But this final one just won't budge. I even opened the bleeder and bled some fluid to see if i would let enough pressure out but made no difference. If I turn the car on and pump the brakes the piston does push out but even with the clamp it will only go back into a certain point but then no further.

Any one got any ideas?

(ps: thought i should put this thread in this section since its a generic brake question)

Something seriously wrong there. Normally they slide in nicely right to the bottom of the bore using a "G" or proper brake clamp. I'd pop the piston right out by pumping the brake pedal. I did this for all of the calipers on the first TS I owned, figuring they would be full of wear material from the brake master cylinder rubber components, etc. Brakes were a lot smoother afterwards.

Examine and clean out the caliper bore and look for damage to the bore and piston. If there is a wear ridge or any other damage, replace it. Does mean you need to bleed all your brakes though.

Yeah I thought a full bleed was gona need happen when i decided to loosen the bleeder to see if it would help. Already got some new Dot 4 in the shed.

I did push the piston right out by pumping the brakes so it was loose but still sealed in the rubber boot. Wasn't sure if it was a good idea to pull it right out of the boot but I spose thats the next thing to try so I can inspect it.

Work the boot down the piston as the piston comes out. Once the piston is out of the rubber boot the boot itself can be removed too. When you put it back together, put the boot on the piston first, with the rim that fits in the caliper overhanging. Work that into the groove of the caliper, then slide the piston in, moving the boot back up the piston to the original position. Don't forget to remove the bleeder valve completely and clean it out while it's all apart.

Ditch the grips and get a brake caliper piston tool for about $15 from your local repco - much easier than trying to brute force the piston back in with grips or by hand.

Might be a basic question, but have you removed the cap off the brake fluid master cyclinder/reservoir? If that's still shut then it could be very hard to work against the pressure in the lines, especially if its overfilled.

Otherwise as Nem says get a proper tool to push the piston in with. Personally I use put the old brake pad against the piston and tighten using a massive 40cm concreters G-clamp. Hasn't failed me yet.

Otherwise you brake piston may have rusted shut. If you're going to rebuild the brake assembly/piston then spray some WD40 in there to try loosen it up.

All fixed. Pulled the piston and boot right out and re-seated it. Cylinder looked perfect on the inside, no damage at all. Seems you do need to get the piston in completely straight to get it in, took a few tries but once i found that sweet spot it slid in easily with the G clamp. Think i will invest in a proper piston clamp if i ever do this again, hard to get it straight with the G clamp.

Tested by starting the car and pumping the pedal until fluid was in the caliper again. Both rears are locking up with the pedal held in then releasing normally so all seems good. Obvioulsy going to do a full bleed now but that will have to wait until tomorrow, you would think it was new years eve or something crazy like that with all these social engagements getting in the way.

And yes i did remove 2/3 of the fluid and left the cap off before i started as suggested in the workshop manual and other threads i found on the topic.

Thanks for the help guys.

Bleed finished. Only hitch was one of the bleed valves being a bit stubborn to open. Test drive successful, brakes feel good. Only strange thing was warning light came up on the dash when i first started the car but went away about 30 seconds driving down the road.

Bleed finished. Only hitch was one of the bleed valves being a bit stubborn to open. Test drive successful, brakes feel good. Only strange thing was warning light came up on the dash when i first started the car but went away about 30 seconds driving down the road.

People generally overtighten the bleed valves, or leave the cap off and moisture from the air attracted by brake fluid rusts them in. Can snap off if not careful.
Low fluid level in the reservoir will set off the hand brake light, if it gets stuck down when you top up.

Yeah the caps were missing of both the front bleed valves. Will get some replacements when I am at the wreckers next. But it was actually one of the rears that was being stubborn. Also its strange that the front twin pistion calipers have smaller bleed valves than the rears even though they are physically bigger :confused: