Rear rotors wear

na, prius rotors rust from lack of use. and rear get less than front. you should pull everything apart and do a rear brake service though. the slide pins can bind up if not clean and well lubricated, which can lead to sticking pads and premature wear.

 

just cleaning and lubricating. there are some good threads here with pics and step by step instructions. check member 'mendel leisk'.

 

Brake Caliper Slide Pin Cleaning and Lubrication | PriusChat

 

Has anyone worked on your rear brakes? There's a pin on the back of the inside pad, that has to be in between the raised spokes on the caliper piston. If it mis-aligns, rides up onto the spoke, it'll cause the pad to press more on the outer edge (where the pin is), less or none on the inside edge.

A few things you can do for quick check, in order from simplest to more involved:

1. After an extended drive immediately feel the rear wheels, how warm they are. Then reach through the spokes and feel the disk itself. Compare sides, and front to back. If one or both rear disks are markedly warmer there could be an issue.

2. Crawl under the rear (there's enough room without raising) with a strong light, and check the inside face of the rear disks. There's a slim gap between the dust cover and caliper, just enough to see the inside face condition. If there's a misalignment of that pin, you'll likely see a rusty, unused zone, towards center of the rotor.

3. Raise the rear end and the parking brake released try turning the wheels. There will be a slight amount of drag due to the nature of the parking brake mechanism's auto adjustment, but it shouldn't be tough to turn the wheel. If there's real drag, they're hard to turn, there's an issue.

A few pics, #4 shows rusty zone on rotor, what misaligned pin can do:

(excuse the mis-rotation, IPhone jpeg format messing everything up)

#1, outer face of rotor, pretty scored:



#2, outer pad, kinda pitted:



#3, inner pad, note unused zone:



#4, inner face of rotor, note rusty (unused) zone:



#5, Piston face:



#6, chewed up pin:

 

I ended up deep-sixing the above pads, and replace with nice new, shiney clean ones. I suspect what happened was they got misaligned when a body shop replaced our rear suspension, the pin and spoke thing. I also took the rotors off, and opted to just clean them with steel wool. Better would be machining, but they seem to have bounced back. When I first put everything together and test drove, they sounded nasty, I guess the new pads burnishing the previously unused zones on the rotor. That smoothed out completely in a few days.

Shiney new pads :



You can see the pins, on all pads, but only the inner ones utilized (the pads with handles)

 

This is the same rotor you see in pic #1 above, looking thru spokes, just now. No machining of the rotor was done, basically the pads cleaned it up.

 

Barely warm is good, means none are dragging unduly. And how warm? If the front and back are about the same: also a good sign.