I’m replacing the rear pads and rotors on an 06 grand prix. I’m trying to compress the caliper cylinder back to be able to slide it over the new pads. Are these calipers supposed to retract the same way the front calipers do? I removed the emergency brake return coil spring thinking this was preventing me from retracting it but it won’t budge using a C- clamp.
If the e-brake system uses the caliper to apply the brakes, the piston must twist in on a screw bolt the e-brake system uses. The face of the piston should have two indentions, groves, or slots that line up with pins or dimples in the back of the brake pad. These are to prevent the piston from rotating when the e-brake is applied and the screw turned. I’ve used a screwdriver and needle-nose pliers opened to fit the indentions to reset these pistons in the past. Be careful to determine which direction pushes the piston in. You don’t want to accidentally pop the piston out. The local auto parts store should also have one of these tools to make it easier ($6.99 at my local Autozone):
http://contentinfo.autozone.com/znetcs/product-info/en/US/otc/4589/image/2/
Darrel, The Piston Must Be Turned Into The Bore Until Seated, But You Must Also Align The 2 Cut-Outs On The Piston Face So They’re At The 6 And 12 O’Clock Positions After They’re Bottomed.
Note: I’m going by what my information says, but if you look at the pistons and look at the pads you shold be able to see why these cut-outs have to be oriented a certain way to allow the pistons to go over the pads.
My infomation states that after the piston is bottomed into the caliper bore you should gently lift the caliper rubber boot’s inner edge (piston edge) and press out any trapped air.
When the pads go on, position the wear sensors (outboard pads) downward.
That’s about all I’ve got.
CSA