Rear brakes are wearing out every couple of thousand miles. What am I missing

probably rust. can you give us a detail of what was replaced at what mileage?

 

The brakes are most likely dragging, wearing out the pads prematurely, and decreasing your mileage. Get them checked/serviced.

Jack up the rear of the car, release the parking brake, your rear wheels should be able to spin freely with minimal, if any drag from the brake pads.

 

Who's doing the replacement? If you: are you positioning the calliper piston cross pattern correctly?

 

I had a seized caliper on my 2010. Brake drag was awful.

I ended up sourcing a used caliper from a salvage yard, replaced it myself.

So....this could be your issue

 

are you lubing the slide pins?

 

I understand. Just wondering: are you positioning the cross pattern so that the pin on inner pad backing plate falls between the spokes of that pattern. This is critical to avoid drag, uneven wear and premature pad wear out.

 

mendel has a whole library. hang on...

 

Hah was going to say can do, later, then look down the the page at the linked threads and what do I find:

New rear pads and rotors 2010 prius-DIY-Here's how | PriusChat

Here's a repeat of pic from above link. Red dot represents pin on pad back:


Red dot shown at 6 o'clock, might actually be at 12 o'clock, but you get the picture: that's how piston must be oriented, and the pin needs to stay solidly locked into the pattern thus. You want to get it well seated by brake pedal application, take a test drive, and only after apply the parking brake. To test: raise the back end and see that the wheels spin semi freely.

 

Make sure the pads are sitting on that red nipple.

 

Here's an inner pad, cleaned and reassembled. You can still see the imprint of the piston spokes, and pin on back of pad. The pin the prevents the piston from rotating. If it does manage to rotate, and the pin rides up on a spoke, then you no longer have uniform pressure:



Here's a pulled off caliper, with the piston in the wrong orientation:



And what the inside pad can look like after a few months of the pin riding up on a spoke. The outer edge of pad (and the pin) are near my thumb. Note the wear is all on the outer 50%, constanly dragging too. The rest of the pad, on the inside, is picking up rust from the unused portion of the rotor:



And how the inside face of the rotor looks:



Basically I messed up when I first looked at the rear brakes, paid no attention to the piston orientation, and this is how it looked about 6 months later. What I did then was take the rotors right off, burnish them well with steel wool. New rotors would be good, but I'm cheap, and they had plenty of thickness still. Then installed brand new pads, and made really sure the piston pattern was oriented correctly, and locked in.

They sounded like heck at first, very noisy every time brakes were applied, within a week or two you'd never know, back to normal.

 

I think you found your cause.