Strange Rotor Wear/Spots

[Steve Tanner]

Just did the front brakes for the first time on my '17 EL at 95k. They were ready - 2-3mm left on the pads, but no issues at all in terms of brake performance. No pulsing, steering shake, or anything odd, just smooth braking like the day we got it with 49k on it back in 2019.

We're in the AZ desert, so we don't really have moisture or rust issues. The caliper pins still slid in and out perfectly. I would have been 100% comfortable putting them back exactly as they were if I didn't want to change the pin boots, as the AZ dry heat does bad things to rubber. No evidence of stuck calipers or anything wrong with the overall system. The rotors were a little bit reluctant to let go of the hub, but that's to be expected after 8 years and almost 100k miles.

I've done a fair number of brake jobs, and I've never seen rotor wear spots like this on brake systems that did not have any obvious issues. All 4 pads were within 1mm of wear, no funny angles or anything. As far as I know, these are the factory pads and rotors. We mostly use the Expy for family highway travel and occasional trips to Costco, so it wouldn't surprise me if these were original.

Have any of you seen wear like this, or know what caused it?

 

[JamaicaJoe]

Do you routinely drive off road or on gravel? Use brakes on long downhill runs?

 

[JamaicaJoe]

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www.ebcbrakes.com

 

[Yupster Dog]

Have any of you seen wear like this

What does the pad's surfaces look like?

 

[Taekwondad40]

Was maybe a lubricant got in there, or the caliper leaking slowly? Really interested in what the brake pad surface looks like.

 

[Steve Tanner]

Hey guys, sorry I didn't get notifications of your replies (guess I needed to click the box). Anyway, I didn't take pics of the pads themselves, but they were smooth with some minor cracks in the friction material on one of them. The cracks were very small, like maybe a sheet of paper or two thick and 1/2" long. Looked normal to me.

I did notice that the pads were worn down to the point that there was no "gap" in the surface anymore. They were solid from end to end, whereas the new pads have a 1/4" space running vertically through the friction material. So maybe that didn't allow heat to dissipate correctly?


This is mostly a family trip vehicle, about 6,000 mi/year. We very rarely drive anywhere that isn't paved (suburban Phoenix area). Sometimes my wife drives it 2-3 miles to the store if none of the smaller cars are here.

I did tow a ~5500lb (with stuff, 4000lb empty) trailer last summer up to Flagstaff and back, but that's not a particularly tough run up I-17. I didn't notice the spots until last fall when I did my usual quarterly maintenance stuff (air, oil, fluids, etc.). That's when I ordered the brake parts but didn't get to it 'til now as there was still more than 1/8" of pad left and it felt ok.

The link JamaicaJoe posed looks like the right answer, the question is why it got hot enough to do that. There were no caliper leaks, when I pressed them back the fluid level went exactly to the reservoir full line. The slide pins were good, everything feels (and felt before) perfect. I don't think my wife is riding around with her foot on the brake (I have the opposite problem, she likes that ecoboost power too much ).

For now I'll just keep an eye on it, maybe check with the thermal gun for a few drives to see if there is any imbalance in temperature.