GL Class (X164) 2007-2012: GL320CDI, GL420CDI, GL450, GL550

Replaced rear brakes and rotors. Did I screw up?

Old May 9, 2021 | 07:58 PM
  #1  
majorchamp's Avatar
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2011 GL450 VIN: 4JGBF7BE8BA706134
Replaced rear brakes and rotors. Did I screw up?

So just replaced my rear brakes and rotors. Went with Brembo rotors and Akebono pads.

The rotors came with what appeared to be a blue/grey'ish powdered coating on them. The videos / recommendations I had seen regarding rotors in the past involved cleaning them with brake cleaner to remove any residues or greases that are sometimes used to prevent rust (I assumed from sitting around).

So upon doing this to these rotors, I realized the coating was getting wiped off revealing the shiny metallic rotor. So that is problem #1...I don't know if that itself IS a problem and I need to fix immediately, or it's more of an appearance issue and doesn't affect the performance or quality of them. The way the coating wiped off and looked "cakey" make me think that is similar to what I might see with the brake pad over time.... You can see the new rotor on the left (and the residue I didn't wipe off) https://i.imgur.com/xoOU8RL.jpg

Problem #2 was I didn't use blue loctite liquid on the screw that you put into the rotor. I actually don't remember if the Brembo rotor screws came with anything on them or not, it is possible.

Problem #3 was I added the brake grease Akebono sent me with the pads on the side grooves and caliper pins, but didn't add any to the back of the pad or to the track in the brake harness. Realized I should have wirebrushed/sanded/filed the track as well, but didn't.

Do 'any' of these problems represent the need to jack the car up and address any issues immediately? I just am experiencing some self doubt on it now.
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Old May 9, 2021 | 08:42 PM
  #2  
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Originally Posted by majorchamp
So just replaced my rear brakes and rotors. Went with Brembo rotors and Akebono pads.

The rotors came with what appeared to be a blue/grey'ish powdered coating on them. The videos / recommendations I had seen regarding rotors in the past involved cleaning them with brake cleaner to remove any residues or greases that are sometimes used to prevent rust (I assumed from sitting around).

So upon doing this to these rotors, I realized the coating was getting wiped off revealing the shiny metallic rotor. So that is problem #1...I don't know if that itself IS a problem and I need to fix immediately, or it's more of an appearance issue and doesn't affect the performance or quality of them. The way the coating wiped off and looked "cakey" make me think that is similar to what I might see with the brake pad over time.... You can see the new rotor on the left (and the residue I didn't wipe off) https://i.imgur.com/xoOU8RL.jpg

Problem #2 was I didn't use blue loctite liquid on the screw that you put into the rotor. I actually don't remember if the Brembo rotor screws came with anything on them or not, it is possible.

Problem #3 was I added the brake grease Akebono sent me with the pads on the side grooves and caliper pins, but didn't add any to the back of the pad or to the track in the brake harness. Realized I should have wirebrushed/sanded/filed the track as well, but didn't.

Do 'any' of these problems represent the need to jack the car up and address any issues immediately? I just am experiencing some self doubt on it now.
# 1 is a non issue, there ain’t no brake cleaner in the world strong enough to dissolve metal brake discs

2 is a non issue, you have 5 lug bolts also holding that brake disc on when the wheels are on.

3 well hopefully it won’t migrate out on the pad or disc

just bed the pads in and you’ll be fine. Back brakes are mostly along for the ride anyway.

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Old May 9, 2021 | 09:28 PM
  #3  
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Originally Posted by Max Blast
# 1 is a non issue, there ain’t no brake cleaner in the world strong enough to dissolve metal brake discs

2 is a non issue, you have 5 lug bolts also holding that brake disc on when the wheels are on.

3 well hopefully it won’t migrate out on the pad or disc

just bed the pads in and you’ll be fine. Back brakes are mostly along for the ride anyway.
Thanks. I added the grease to the red dots in this picture (I added the red dots) https://i.imgur.com/Tsiz8Jv.png (and then the surfaces of the pins: https://cimg3.ibsrv.net/gimg/www.mbw...cdc37361bb.jpg) (not my pic, just for reference).

Regarding #1, just to be clear, I wasn't sure if I was "supposed" to leave that coating on. Browsing around, it sounds like some rotors (like zimmermans) are intended to be left on, and the pads will just wear the surface contact area clean after a few uses. The fact brake cleaner took it off so effortlessly on the Brembos made me think that material wasn't super important.

Though...I looked at the paperwork (after the fact, dumb me) and the Brembo instructions did make a mention of not using aersol brake cleaner on them and just using soap and water. So hell if I know at this point. I just want to make sure removing the coating isn't going to turn them into **** or somehow harm the pads....
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Old May 10, 2021 | 07:25 PM
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GL550 X164
Originally Posted by majorchamp
Thanks. I added the grease to the red dots in this picture (I added the red dots) https://i.imgur.com/Tsiz8Jv.png (and then the surfaces of the pins: https://cimg3.ibsrv.net/gimg/www.mbw...cdc37361bb.jpg) (not my pic, just for reference).

Regarding #1, just to be clear, I wasn't sure if I was "supposed" to leave that coating on. Browsing around, it sounds like some rotors (like zimmermans) are intended to be left on, and the pads will just wear the surface contact area clean after a few uses. The fact brake cleaner took it off so effortlessly on the Brembos made me think that material wasn't super important.

Though...I looked at the paperwork (after the fact, dumb me) and the Brembo instructions did make a mention of not using aersol brake cleaner on them and just using soap and water. So hell if I know at this point. I just want to make sure removing the coating isn't going to turn them into **** or somehow harm the pads....
I left the coating on and the pads cleaned it up. It's probably used to prevent the rotors from rusting when in the box and waiting for their next home.. Imagine buying a brand new rotor, opening the box and seeing rusty rotors. So yeah... marketing.

Like Max said, nothing to worry about.

Re: 3, I apply a thin coat to the ears which you marked in red. All sides. Also a thin layer on the back of the pads, especially the one(s) being pushed by the piston. If you did not, no big deal. You can do that the next time you change wheels. Remove the bottom bolt from the sliding pin, flip the caliper up, prop it in place with a screwdriver or hold with one hand, with the other hand apply thin layer of grease on the back of the inside pad. Reverse steps to get the caliper in place.

I've never used locktite on any of my replacement rotor screws over 20+ years and have had no problems at all. You can also add some locktite on the screw when you have the wheels off at the same time, if you wish.
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Old May 10, 2021 | 09:04 PM
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2011 GL450 VIN: 4JGBF7BE8BA706134
Originally Posted by expl0rer
I left the coating on and the pads cleaned it up. It's probably used to prevent the rotors from rusting when in the box and waiting for their next home.. Imagine buying a brand new rotor, opening the box and seeing rusty rotors. So yeah... marketing.

You can do that the next time you change wheels. Remove the bottom bolt from the sliding pin, flip the caliper up, prop it in place with a screwdriver or hold with one hand, with the other hand apply thin layer of grease on the back of the inside pad. Reverse steps to get the caliper in place.

Just to make sure I follow. Do you mean the bottom caliper pin...what he is removing at 1 minute in?
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Old May 10, 2021 | 09:32 PM
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From: Yeast Coast, Canada
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Originally Posted by majorchamp
Just to make sure I follow. Do you mean the bottom caliper pin...what he is removing at 1 minute in? https://youtu.be/9pOv5jYFve0?t=59
Yes. The upper bolt may need to be loosened a bit to rotate the caliper on the bolt's axis, but does not need to be removed. I save time with this approach. I use it to also avoid any extra strain on the brake lines from twisting, or dropping the caliper accidentally.
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