Brake piston retaining plates?

[radley]

I recently purchased a pair of rebuilt front calipers that the piston retaining plates from my old calipers do not fit on. The piston seems to be rotated 180 degrees so the plates will only fit upside down. Since it took a while to get the calipers I'd rather not send them back, so my question is: what is the purpose of the plates, and is it ok (i.e. safe) to use the calipers without the plates?

[jamcleod]

? check and verify that the piston is installed correctly... it could be the piston is 180 out

[Dave at Pelican Parts]

The purpose of the plates is to keep the pistons from rotating in the caliper. The pistons have specific shapes to their ends to make sure that the brake pads wear evenly. With them turned around, I would expect a fairly significant amount of "taper wear" in the brake pads. I don't think they'll be unsafe to use, but it would be preferable to have them in the correct orientation.

Check the pads more often than you would otherwise. Look at the inside edges as well as the outside edges of the pads.

Hmm, I wonder if the pistons could simply have been swapped, left for right? If so, the pads might wear OK...

--DD

[mskala]

You can just rotate the pistons to the correct position yourself.
They can rotate freely, just stiff. You probably could take off
the dust cover and grab it with something soft to protect it.

[radley]

Thanks guys. I was able to roate the pistons so that the plates fit on now. Better safe than sorry!