Rear caliper inner piston help needed, I did search and found some threads, but could'nt nail it Options

[Root_Werks]

Searched and couldn't nail exactly the help I was looking for. So figured I would ask in a new thread.

My rear brakes I let the pads wear waaaay to far. Well, I've only driven the car a few hundred miles and I thought they had more meat on the pads. Nope. Long story short, both pistons on the outer sides pulled in via the adjuster just fine but both inner appear to have gone past the threads. I can't seem to get them to catch back onto the adjuster. Anyone have any tricks?

[davep]

IMHO the venting clearance on the rear brakes (0.004") should be done about every 5 to 10 thousand miles. As the pads wear, the piston is hydraulically forced out, but the internal mechanism does not necessarily follow. If the pads wear 0.125", then the mechanism can be pulled out of the groove in the piston and are thus disconnected. If the clearance is never adjusted from new thickness to worn completely away then you can wind up in the situation you find yourself in. I have, many times, received calipers where the mechanism is not connected; I'd guess 60% of the calipers. In many cases I turn the adjuster CW to force the mechanism out until it snaps back into the groove; about 80% success rate. However, to retract pistons in a rusted caliper you almost always need to apply pressure on the face of the piston. My spreader tool gets an awesome amount of service in these situations. My rule of thumb is that if the adjusters do not move the pistons by themselves, then it is time to rebuild.