The car is a 2012 Gen three with 250,000 miles on it. I bought the car with a blown head gasket about 14 months ago, and I put 20,000 miles on it. When I bought it I replaced the rear pads and rotors with some nice Bosch ones from rock auto. While replacing one of the wheel bearings this weekend I took a look at the pad wear and did not like what I found. The inner pad on both sides was almost worn down and was about to start squealing, but the outer pads had a lot more material on them. I have not looked at the front pads recently, which were replaced around the same time. When I bought the car it had been a similar situation, the rear inside pads were very worn and the outer pads were almost untouched. The slide pins had been very frozen. I was sure to remove the slide pins, clean them up and replace the ones that needed to be replaced. I also swapped out any boots that were torn or really swollen. Yesterday I took the two outer pads from the old set and put them on the inside and reassembled the brakes. I will not have the squeal now, but at least it lets me use up the old pads. When reinstalling I took the pins out again, and clean them off as well as using the right sized(?) drill bit to drill out the slide pin tubes to get rid of any corrosion built up in there. The pins on both sides still moved pretty well as far as I would think, and if not for the uneven wear I would have not have touched them again. The caliper on the driver side was a little hard to compress, and a drive around the block confirmed that it was getting stuck. It was literally smoking after driving a couple thousand feet. I had a junkyard caliper for that side already, and I removed the seal from the one on the car and applied it to the junkyard one and put that on the car. The junkyard piston looks really clean on the part that slides in an out, but the one that came out of the car had some corrosion on it. Here is what they look like. On the side that was not stuck accidentally unseated the seal while compressing the piston, so I had to be reassembled as well. That piston looked very clean on the sliding surface. I hear stories of these cars going for more than 50,000 miles without having to touch the brakes. Any idea what is going on here? When I reinstalled the pads I made sure that they could slide very easily in the bracket so hopefully I have covered all my bases. Both of the dust shields on the back are rusted away, but I really would not believe that their absence has caused this much of a difference. The back surfaces of the rotors look comparable to the front surfaces. Unfortunately it looks like Bosch only warranty is there a brake pads for 12 months. Here are the pads I used, BOSCH BC1423. This just seems like such a short time for them to wear out, and on the rear no less! I have driven most of those miles, and I am a light hypermiler, so I have a soft foot on the brake whenever possible. My wife has been driving it more the past few months and she would be fall more in in the normal driver category. I have heard that most cars start to apply the brakes in the rear and then the front once you are on the pedal more.
I only have a foot on the brake when......I brake. I put over 150,000 miles on two of these cars that were owned by my employer. The brakes were never 'touched' (worked on?) on either of these two cars - but I live in the habitable zone of our nation, and we only use salt in the kitchen. OK.... Maybe not habitable in the summer months....if you have the 'olds' and you're intolerant to heat and humidity that are both in triple digits before lunch. There's a LOT going on here, but I think I would check your work. Maybe replace the pads again and check the wear rate, since they're only $30-40 a set. The Googles say that these are ceramic discs, BTW. If Priuses came with ceramic discs - this is the first I'm hearing about it. They DO come with dust shields for a pretty good reason though! I'd think about replacing yours while you're in there.
Might be misaligned caliper piston; it's got a pattern that HAS to mesh properly with the pin on the pad backing plate. More info in my signature. (if on a phone you'll need to hold it landscape oriented to see signatures)
In the interest of science, about a month ago I took the bearing back off and put a new dust shield on. In theory I will see in 12 months if the inner and outer pads are worn the same. However, I may be selling it to a friend before that time. And I did make sure to have the caliper pistons aligned correctly.
