Second set of rear brakes on 2016 EB done at 6K miles?

[Mr981]

In late 2019 I had the brakes inspected on the car by an Indy; the car had 48K miles.
His work included a disassembly of the fronts, lubed moving parts and kept the OE front pads because they were within wear tolerance.
The rears had more wear-- strangely--down to 3mm on the pads and the rotors were marked up.
He replaced the pads and rotors and all was good.
This year the braking performance seemed to be a bit off and had a bit of pulsation with it.
Took it back to the dealer for this and other work and got a call saying I needed rear pads and rotors.
I was surprised to say the least, given there was only 7k miles on the those new rotors and pads.
I told the dealer to skip it until I had a chance to get the car back and eye ball the rotors and pads, then chat with the Indy about how these parts could go south in 7K miles.

Questions:
-Regarding stock pads and rotors--any preferences as to which brands should last the longest in mostly city driving?
-Also, the rotors used had their hats rust--any decent coated rotors out there for the rear brakes?
-Last, I also surprised the fronts continue to wear well, considering that handles most of the braking effort; any reason why these rears should wear so quickly?
thanks for any help in advance.

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[EFI]

why these rears should wear so quickly?

One of two things come to mind. Either the parking brake is sticking and causing continuous friction on the pads and rotors even when you're cruising and the brakes are not in use, or the ABS/traction control system is malfunctioning and once again applying excessive pressure to the pads keeping them in contact with the rotor continuously and wearing them down.

My stock rear pads lasted me well over 30k miles and 20 track days, so 6k miles on the street is definitely an issue.

 

[Brian@BMVK]

You have a stuck/seized caliper or parking brake. It may need to be rebuilt or replaced.

 

[Mr981]

Thanks for the replies.
BTW, do you know what the stock thickness of pad material is on new rear brakes?
Also, what's the thickness of of the rear rotor (non-PP)

 

[Brian@BMVK]

BTW, do you know what the stock thickness of pad material is on new rear brakes?

Don't know exactly, but about 10 mm, maybe a tad more.

 

[Cobra Jet]

One of two things come to mind. Either the parking brake is sticking and causing continuous friction on the pads and rotors even when you're cruising and the brakes are not in use, or the ABS/traction control system is malfunctioning and once again applying excessive pressure to the pads keeping them in contact with the rotor continuously and wearing them down.

My stock rear pads lasted me well over 30k miles and 20 track days, so 6k miles on the street is definitely an issue.

I would agree with the above analysis for sure.

The only way pads will wear excessively and prematurely (aside from use in racing events or severe use) is that the bias to the calipers is off, a binding caliper piston, malfunctioning ABS or the e-brake which is causing pressure on the pads against the rotor while driving.

Have you noticed any smoke or burning odor (like clutch burn) from the rear of the car after parking? Or if say going on a night drive for a few miles and parking, do you see anything glowing?

 

[Mr981]

I would agree with the above analysis for sure.

The only way pads will wear excessively and prematurely (aside from use in racing events or severe use) is that the bias to the calipers is off, a binding caliper piston, malfunctioning ABS or the e-brake which is causing pressure on the pads against the rotor while driving.

Have you noticed any smoke or burning odor (like clutch burn) from the rear of the car after parking? Or if say going on a night drive for a few miles and parking, do you see anything glowing?

I haven't smelled anything after driving but I'm going to take off a wheel and measure the rotor thickness and pad thickness for myself. The rt rear rotor--the one with the pad at 3mm reportedly--visually doesn't look worn and doesn't have much of a lip on it that I can see with the wheel on. If the measurements from the dealer are real, I'm going back to the Indy and let him explain it.

 

[cmxPPL219]

I haven't smelled anything after driving but I'm going to take off a wheel and measure the rotor thickness and pad thickness for myself. The rt rear rotor--the one with the pad at 3mm reportedly--visually doesn't look worn and doesn't have much of a lip on it that I can see with the wheel on. If the measurements from the dealer are real, I'm going back to the Indy and let him explain it.

Even if you don't smell anything, after a decent drive, get out and feel the temp of the wheel around the lug area. The rear should not be hotter than the front, as the front does most of the braking. If both of the rears or one of the rears feels extra hot, this is a tell-tale sign. (If you have a temp gun, aim it at the rotor faces, use this to compare fr and rr temps.)

Also, look for more brake dust on the rear wheel compared to the front, as this can also be a tell-tale sign, depending on the pad compounds.

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