Trying to change pads on a 93 lumina with rear disk brakes, and I can't seem to get the piston to compress in the caliper. I know I'm supposed to be turning it with a spanner tool, but no matter how much I turn it goes no where. I am putting pressure on it at the same time as well. The manual clearly say to rotate the piston, but it doesn't say which way. I found out by trial and error that clockwise (facing the piston) makes the piston come further out, but counter-clockwise just spins but won't compress. It seems to me like I'm using enough pressure, but from what I read it requires a pretty large amount of force to do. I read about a better tool, a combination of c-clamp and spanner tool, that will compress and spin the piston. I'm wondering if this tool will work for me since my pistons need to be spun counter-clockwise, which seems like it would be loosening the c-clamp? Any additional advise on doing this?

 

my 84 fiero had f-up rear calipers like that. I believe for that design you have to remove the ebrake lever on the caliper to allow the internal screw in the caliper to retract when the piston is turned.

 

Yeah come to think of it my 87GT Fiero is the same way as well, just been so long since I messed with the rear brakes I'd forgotten about it. Got the pistons compressed back in the calipers finally today after figuring out a creative way to do it. Thought I would post the details in the event someone finds this thread in the future with the same problem.

The manuals all say to rotate the pistons, but don't bother to tell you which way. The drivers side piston needs to spin counter-clockwise, and the passenger side spins clockwise in order to compress the piston. I used a large C-Clamp that had a pivoting plate on the screw end. Tighten it down snug, but don't force it. Then get a pair of channel locks and grip the lip of the piston, and turn it the correct direction for the wheel your working on. As you spin the piston it will compress, so you will need to tighten up the c-clamp as you spin the piston under it. Worked like charm without needing to rent any special tools.