Contour Enthusiasts Group Archives Forums Modifications Brakes Rear brakes

Just curious about something...I was changing the rear pads and noticed something. The piston turns when it moves out to press against the pad. Now after you put the pads in and you lower the caliper cover down to lock it all in, you have to put the little tab on the inside pad inside one of the 4 grooves on the piston. So when its closed up, and that tab is in one of the grooves, how is that piston supposed to turn in order to move out against the pads? The piston will try to spin but that tab thats in one of the grooves will stop it. The only reason I'm thinking about this is because my rear passenger side pads (only that side) are always loosening up and rattling when I go over bumps, so I have to go in there, turn the piston a quarter of a turn (about), and then the sound goes away for about two weeks before returning again. And yes the pads are tight when I first put them in. The piston is backed off just enough for the top to close. Can anyone clearify this for me?

The button that contact the pad on the rear piston may want to turn on it's way out but it's prevented by doing so by the raised bumps on the backside of the pads. This phenomenon may be just the fact that is has this thread that you use to srew in thepiston and on the way out it will want to follow that thread again, but what actually happens is that the piston inside will spin instead when the outer button sees resistance.

Unlike the front calipers there is a button mouned on to the actual piston, at least this is how I assume it works.

so is there a reason why the pad would continue to loosen up in a short period of time? Seems like after a while, the pad has play and will rattle around when I go over bumps. Is that a sign of a bad caliper?