I did a brake job on a 06 Corolla with 37,501 miles over the weekend. I noticed that the left front brake caliper's dust boot was slightly distorted. By that I mean a 2-3mm section of the dust boot was sticking out very slightly once the piston was fully retracted. The dust boot wasn't cracked, but a slight edge of it was sticking out and covering the lip of the piston. It appeared as though once the piston was pushed out, the dust boot would pop back into place.

The pads that I removed from the left front caliper looked like this:


2mm

1.5mm

The pads from the right front caliper, which did not have any dust boot problems, looked like this:


3.5mm

2.5mm

Not as bad, but still nearly worn out. The difference in pad wear is around 2mm. However, BOTH rotors were badly grooved, even on the right front caliper for some reason. The rotors looked like this:



When you run your fingernails across the rotor surface, you can definitely feel the grooves.

I went ahead and installed Raybestos Advanced Technology ceramic pads and Raybestos Advanced Technology rotors. The new pads and rotors gave the pedal a firmer feel and greatly improved the braking performance. I'm guessing that while the dust boot may not be in greatest shape on the left front caliper, it isn't bad enough to warrant replacement. There's only a 2mm difference in pad wear between the LF and RF calipers over 37.5k. The driver of this vehicle is on track to wear out pads every 20-25k with her current driving style.(she bought this car used with 27k and wore out last 50% of the pads during the last 10k)

What do you guys think? Should I just tell her to not worry about it in the meantime and just replace both calipers at the next brake job as preventive maintenance? Or is there nothing to be concerned about?

Thanks.

 

Could have a stuck caliper its actually fairly common

The rotor looks normal to me. Those fine grooves are very normal and I would only be alarmed about larger grooves.

 

Does the car pull to one side while braking?

 

Not at all. Could it be just a slight stick?

 

I tried to make a drawing of the problem:



The black ring is your dust boot. The black shaded part is how the dust boot is contacting the piston "lip." Nothing is torn. It appears to me as though once the piston is pushed out, the dust boot will be normal again. However, this doesn't explain the strange pad wear. Perhaps that's a completely separate issue altogether?

 

Make sure the caliper slides are lubed too. But then again I doubt that the caliper's stuck if the brakes don't cause a pull. It could also be that one side is more worn than the other because the o-ring is worn, and not returning one piston properly but then I don't see that happening on such a low mileage car.

Kinda puzzled how one side would have more wear than the other but there isn't an induced brake pull

 

More wear on one side is either one side doing more of the braking or the caliper hanging up more on that side usually. The boot being bunched up may not be a issue. Did the piston compress easily without force?

 

As I recall, both sides compressed with about the same force.

Someone loaned me a c-clamp that was way too small, so I had to attach a socket to the end of it in order for it to be long enough to compress the piston. Therefore my perception of feel is a bit whacked.

 

I called the local dealership and spoke with a technician. He told me that the distorted dust boot was a the result of an air pocket. He told me to poke a hole in it and tuck it back in. I told him that I just pushed it back the best I could and reassembled it, he said that was fine.

As for the pad wear, he said some difference between the LF and RF caliper is normal. Unless one caliper was at 10mm and the other was at 3mm, there's nothing to be concerned about. He also told me resurface the old rotors and reuse them next time.

 

Look where the to long bolts that connect the caliper to the hanger. There should be small boots over those. Get inside there and grease it with a nice high-temp grease. Plus grease up the bolts themselves, but not the threads (the bolts should be long, and have a long area in the middle with no threads, grease that area).