My MKZ has 46,000 miles on it, and probably 20,000 or better of those are highway miles. I've put 16,000 miles of those on it myself, and since I bought the car from in the family I know the history of it going back to new.
A few months ago, I had all the wheels off and saw what I'd consider normal wear on all four sets of brakes, and also even wear across both axles. That was on factory pads all around.
The car is riding on Michelin Primacy MXM4s that were installed about 14,000 miles ago. I had the car aligned when I had the tires put on, and have had two alignment checks since. The last was back in June and it was in spec.
Two weeks ago, I was on the road and started hearing a faint scrape from the right rear every time I stepped on the brakes. I stopped and looked at it, but didn't see anything abnormal. About 50 miles from home, another stop showed a groove about the width of my thumb in the rotor, but I kept on trucking since I was so close and just parked the car until I could attack it. BTW, by the time I was home, the rotor was grooved pretty much the whole width of the pad. I had to move the car in the driveway a few times, and it made a pretty viscious sound when moving with moderate brake pressure, but would go away if there was only light pressure.
What I found when I pulled the pads on that side concerned me...I'm attaching a photo of them. As you can see, the outside pad is down to the metal backing, while the inside is worn pretty unevenly. The wear on the rotor matches these.
The left rear pads looked what I'd consider perfectly normal for ~50K miles, and probably had about 40% life left with even wear across them.
I've been warned of the potential of a sticking caliper, but it doesn't seem to fit here. For one thing, I'd think I'd have heard a constant scrape once it started to act up. As I said, it took moderate brake pressure to make any sound at all. The car tracked straight-that was one of the things that I checked when it started acting up, and I'd expect a sticking pad to cause it to pull.
Also, with new pads and rotors on the rear axle, the car continues to track straight. I have about 200 miles on them now, mixed city and interstate driving. When I first installed them, I did several stops with the handbrake only(the handbrake uses the main brakes, it's not drum-in-disk) and it both came to a stop fine and again tracked straight while braking(whether foot brake or hand brake). I've not seen any evidence that anything is amiss.
Does anyone have any ideas about what could have caused this, and if so what I should be on the lookout for?
As a side note, I borrowed the rear brake retractor tool from Autozone to do this job. After using it and seeing how easy it makes things, I'm never again going to mess around with channel locks or even the cheap "cube" retractors again. For the first one I did, it took me longer to find the right die and get the tool set up than it did to actually get the piston back in...
A few months ago, I had all the wheels off and saw what I'd consider normal wear on all four sets of brakes, and also even wear across both axles. That was on factory pads all around.
The car is riding on Michelin Primacy MXM4s that were installed about 14,000 miles ago. I had the car aligned when I had the tires put on, and have had two alignment checks since. The last was back in June and it was in spec.
Two weeks ago, I was on the road and started hearing a faint scrape from the right rear every time I stepped on the brakes. I stopped and looked at it, but didn't see anything abnormal. About 50 miles from home, another stop showed a groove about the width of my thumb in the rotor, but I kept on trucking since I was so close and just parked the car until I could attack it. BTW, by the time I was home, the rotor was grooved pretty much the whole width of the pad. I had to move the car in the driveway a few times, and it made a pretty viscious sound when moving with moderate brake pressure, but would go away if there was only light pressure.
What I found when I pulled the pads on that side concerned me...I'm attaching a photo of them. As you can see, the outside pad is down to the metal backing, while the inside is worn pretty unevenly. The wear on the rotor matches these.
The left rear pads looked what I'd consider perfectly normal for ~50K miles, and probably had about 40% life left with even wear across them.
I've been warned of the potential of a sticking caliper, but it doesn't seem to fit here. For one thing, I'd think I'd have heard a constant scrape once it started to act up. As I said, it took moderate brake pressure to make any sound at all. The car tracked straight-that was one of the things that I checked when it started acting up, and I'd expect a sticking pad to cause it to pull.
Also, with new pads and rotors on the rear axle, the car continues to track straight. I have about 200 miles on them now, mixed city and interstate driving. When I first installed them, I did several stops with the handbrake only(the handbrake uses the main brakes, it's not drum-in-disk) and it both came to a stop fine and again tracked straight while braking(whether foot brake or hand brake). I've not seen any evidence that anything is amiss.
Does anyone have any ideas about what could have caused this, and if so what I should be on the lookout for?
As a side note, I borrowed the rear brake retractor tool from Autozone to do this job. After using it and seeing how easy it makes things, I'm never again going to mess around with channel locks or even the cheap "cube" retractors again. For the first one I did, it took me longer to find the right die and get the tool set up than it did to actually get the piston back in...
