pitted brake disc

enotslim · Post by **enotslim** » 10 Feb 2019, 12:41

New rear brake pads (Autozone ceramic) 6 weeks ago. Felt mild pulsation I thought was rust that diminished but did not entirely disappear with time. Now about 1 week of increased (but still pretty mild) pulsations. Yesterday I found pitting of the LR disc as shown in the attached photo. Clearly need new discs. Do I also need new pads? I will probably install new pads regardless but just wondering if the pad is likely damaged from mating to the pitted disc.

Plan Akebono pads and AKE discs.

Thanks

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WhatAmIDoing · Post by **WhatAmIDoing** » 10 Feb 2019, 13:14

Inspect pads for uneven wear. Also possible (I have never used Autozone ceramic pads), but they may be too hard for the brake disks and are chewing them up. IMHO, Akebono ceramic pads are the best and a worthy upgrade.

Post by **misha** » 10 Feb 2019, 13:15

Did you "bed-in" new brakes and pads?
Every time you install just pads or both...disc & pads...you need to perform "bedding-in" procedure...or to use brakes carefully and gently for first few hundred miles.

enotslim · Post by **enotslim** » 10 Feb 2019, 13:19

I did the 5 stops from 40 to 5 mph without cooling, then 5 from 20 to 5 with cooling. Didn't smell resin though. Driving is all city so there is some unpredictability, but I also usually drive when few are on the road (4:30 am and 7-8 pm) so it is pretty tame.

greg850r · Post by **greg850r** » 10 Feb 2019, 13:37

Rotor is doing it. Whenever I put a used pad that's grooved or glazed on a new rotor I lay a piece of sandpaper on a table and rub the pad on it until it has a new flat surface. Been doing this for years and never a problem.

enotslim · Post by **enotslim** » 10 Feb 2019, 14:34

The pads were new, not the rotor.

Post by **oragex** » 10 Feb 2019, 14:38

I have the Akebono pads and my genuine discs don't wear like this. Maybe it's the discs, but I also have another rather wild idea.. when installing the new pads, did you push the pistons back without releasing the caliper bleeder? There is a small chance this would get the solenoids inside the ABS valve body slightly stuck and reduce the rear braking pressure which may cause such wear as well.

Post by **misha** » 10 Feb 2019, 15:11

I always push pistons back in without loosening bleeding bolt...that's how they supposed to push back..otherwise you will let air in the line.

Post by **oragex** » 10 Feb 2019, 16:14

When loosening the bleeder bolt, I put over it a small plastic tube sitting tight, about 50cm long going into a can.

Indded, most of the times nothing will happen, but it is possible the back pressure to lock a solenoid inside the ABS body. But in any case, I like to open the bleeder because it's a good moment to bleed the fluid and it also makes pushing back the piston easier. It also helps keeping this bleeder 'removable', when left in there for long time it can get badly stuck.

enotslim · Post by **enotslim** » 10 Feb 2019, 16:52

greg850r wrote: ↑10 Feb 2019, 13:37 Rotor is doing it. Whenever I put a used pad that's grooved or glazed on a new rotor I lay a piece of sandpaper on a table and rub the pad on it until it has a new flat surface. Been doing this for years and never a problem.

The pads were new but thanks for that suggestion. Makes lots of sense.