96 Mercure Sable Wagon Brake repair

I am repacing the read brake pars on my 96 Mercure Sable Wagon. I cannot get the caliper pistons to recede. I tried pressing with clamps etc with a LOT of pressure, but they do not retract. They are not frozen because I can rotate the pistons. I s there some secret to get the pistons to open far enough to accommodate the new pads? John wrote:I am replacing the rear brake pars on my 96 Mercury Sable Wagon. I cannot get the caliper pistons to recede. I tried pressing with clamps etc with a LOT of pressure, but they do not retract. They are not frozen because I can rotate the pistons. I s there some secret to get the pistons to open far enough to accommodate the new pads?
These caliper pistons do not push in. They will rotate clockwise into the caliper to allow for installation of the new pads. Rotate inwards only as far as needed to allow installation of the new pads with the proper clearance to the rotor. Make sure the little “tits” on the pads line up with groves in the caliper pistons.

Just a side note and I say this only because I am a professional technician. This is the most important system on any vehicle, please do the job properly. If you are unsure the investment in a service manual will save many hours, dollars and lives in the long run.
Sorry but I am by the book when it comes to brake work.

Thank you for the information. I have been turning the piston clockwise, but is is still not receeding. Could the threaded section inside be turning? Any way to lock it? Should the Parking brake be set? Unset? Should I open the bleed vent to get this to receed? Thanks again[/b] The parking brake should be off.

What are you using to turn the piston?

As far as I know there is no way to hold the internal threads while depressing the piston. I use a screw type tool which turns the piston while applying inward pressure on the piston. I think AutoZone or Advance auto parts have the tool set for about $50.00. Other wise you will need to find a way to exert inward pressure while turning the piston. Perhaps try turning the piston as you apply pressure with the clamp.

If the brake pads were badly worn (no pad left at all) the caliper pistons may have been hyper extended and may not go back into the caliper. If this is the case you will need to replace the calipers.

It is not uncommon to find bad calipers or bad brake flex hoses on these cars. As a last resort, if the piston will not turn in, open the bleeder valve and try retracting the piston again. If the piston then retracts into the caliper the brake hose is most likely bad.

Good luck, let us know if you have any more questions.