I've got a 2013 CR-V. During a recent service, I asked a tech to take a look at what might be causing a weird smell to come from one of the rear wheels. During the initial look, he noticed that there was a lot of heat coming from that same wheel as well, and after inspection, recommended new pads and rotors for the rear. I do brakes at home because of the cost, but I did get a brake fluid flush done there.
When I started replacing the pads and rotors, I saw that the wheels that didn't smell (both fronts and one rear) all had pretty evenly worn down to 8-9 mm, while the other rear wheel (the one with the smell) had both pads between 4-5 mm. For each pair, the wear was fairly equal for both pads, and that wear was even top to bottom as well.
The rear rotor that didn't smell still had some of the grinding scores still visible on the inside (top right of image). All pads and rotors were new as of June 2019.
Due to the even wearing within all pairs, I determined the slider pins were not sticking. On inspection, this was correct. Due to the flat wearing of each pad, I determined that the pads were not frozen within the bracket shims/hardware. On inspection, this was also correct.
I put the new pads and rotors on, and went for a 15 minute drive. Immediately after, I checked the temperature of each rotor. The rotor that smelled didn't smell any more, but it's temperature was around 340F. The other rotors were all between 80 and 90F. So more work to do.
My limited experience with brakes told me that the next logical place to look was the calipers. But which one/ones? Here's what I was thinking:
- The caliper for the brake with the excessive heat and smell was able to float, but somehow was squeezing much more than the other calipers.
- The other rear brake's pads were hardly worn -- perhaps it was seized?
So I was initially thinking that at least both rear calipers were probably damaged, though in different ways. The caliper across the severely worn pads probably had a seal failure, meaning it's piston wouldn't retract after the brake pedal was released; and the caliper across the hardly worn pads was probably corroded in the cylinder to the point of seizure so that it was never able to significantly engage the pads against the rotors. (Note: since the service tech didn't mention the front brakes, I wasn't thinking about them too much at this point, but as I write this up, I'm not sure why I wasn't applying the same logic to the fronts, based on the equal pad wear with the lesser-worn rear pads.)
In the end, I decided to first replace the caliper across the severely worn pads. I did that, bled the brake line, and went for the same drive again. This time, all four rotors were around 120F. I'm calling that mission accomplished as the even temperatures seem to suggest even pressure across all four calipers.
But, and this is the point of this post, I don't understand why I don't now need to replace the other caliper(s). It seems like the other sets of pads and rotors were barely used at all in those 11 months. Is it possible that a single rear brake has been doing the lion's share of slowing the vehicle down for 11 months? (Note: we haven't noticed pulling to either side when braking.) Or is it more likely that all the brakes have been working equally when the pedal is applied, but the one set of pads just hasn't been able to meaningfully disengage from their rotor for 11 months?