help me understand brakes

umb2021 · 10-07-2023, 01:49 PM

Hello all

I removed some spacers that were really stuck and I had to use a screw driver and a hammer to get the spacers off the car. I finally succeeded but with scratches and small dents in the surface that faces the wheel. See the image and the black arrows.

The scratches are not visible on the image, but they are there and are about 2-3 mm deep.

Does this effect the driving dynamics and braking of the car?

Qsilver7 · 10-07-2023, 03:56 PM

The arrows in your pic are pointing at the wheel hub…not the brakes. The working part of the brakes is the shiny part (the brake disk) that the caliper (the red thingy with the M label) presses the brake pads against…which stops the vehicle.

dscabra · 10-07-2023, 04:21 PM

The scratches are in the rotor hat and will not affect your car's performance at all. In the future, apply a small amount of anti-seize when installing the spacer or wheel and you won't have any trouble getting them to come off.

umb2021 · 10-07-2023, 04:54 PM

Quote:

Originally Posted by Qsilver7

The arrows in your pic are pointing at the wheel hub…not the brakes. The working part of the brakes is the shiny part (the brake disk) that the caliper (the red thingy with the M label) presses the brake pads against…which stops the vehicle.

Correct, when you buy new brakes, you get a new wheel hub right?

dscabra · 10-07-2023, 07:09 PM

Quote:

Originally Posted by umb2021

Correct, when you buy new brakes, you get a new wheel hub right?

It's not the wheel hub. It's part of the rotor, so yes, if you buy new rotors that will replace the scratched ones.

Name: Screenshot_20231007_181253_Chrome.jpg
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Name: Screenshot_20231007_181253_Chrome.jpg
Views: 144
Size: 84.6 KB

Qsilver7 · 10-07-2023, 08:13 PM

Yes…it is the “rotor cap”…which is mounted to the wheel hub…but that part of the rotor doesn’t have anything to do with the active part of braking.

Thanks to the posts above that brought better clarity to what I was trying to say.

Opie55 · 10-16-2023, 10:15 AM

As you know, the picture you posted is so out of focus it does not do us any good. While it is true that defects in the rotor hat where the wheel mounts will not affect braking performance per se, that does not mean that defects will have no effect at all. That surface needs to be flat or your wheel may wobble a tiny bit. It does not really matter how deep a gouge or scratch is, what matters is where the material is that used to be where the gouge now is. If you hit a flat piece of aluminum with a hammer or chisel, you will typically raise up the edges around the resulting dent. It's the raised edges you need to worry about. You should put some sandpaper around something flat and sand any raised areas down.

10-07-2023, 01:49 PM	#1
umb2021 Enlisted Member 1 Rep 42 Posts Drives: BMW 530E Join Date: Dec 2021 Location: Denmark iTrader: (0)	help me understand brakes Hello all I removed some spacers that were really stuck and I had to use a screw driver and a hammer to get the spacers off the car. I finally succeeded but with scratches and small dents in the surface that faces the wheel. See the image and the black arrows. The scratches are not visible on the image, but they are there and are about 2-3 mm deep. Does this effect the driving dynamics and braking of the car? Attached Images
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10-07-2023, 03:56 PM	#2
Qsilver7 Major General 4448 Rep 7,489 Posts Drives: F06 650ix GC / F15 X5 50i Join Date: Oct 2016 Location: Indiana, USA iTrader: (0)	The arrows in your pic are pointing at the wheel hub…not the brakes. The working part of the brakes is the shiny part (the brake disk) that the caliper (the red thingy with the M label) presses the brake pads against…which stops the vehicle. __________________ 2015 F06 650ix Gran Coupe`(Moonstone/Cohiba Brown)\| 2014 F15 X5 50i MSport (Space Gray/Mocha) Become a BMW CCA member! Click HERE to join and feel free to use my BMW CCA member #191509 as a referral.
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10-07-2023, 04:21 PM	#3
dscabra First Lieutenant 4960 Rep 378 Posts Drives: GMC Denali Join Date: Feb 2021 Location: Missouri iTrader: (0) Garage List 1965 Shelby Cobra ( ... [10.00] 2023 GMC Sierra 150 ... [9.00]	The scratches are in the rotor hat and will not affect your car's performance at all. In the future, apply a small amount of anti-seize when installing the spacer or wheel and you won't have any trouble getting them to come off.
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10-07-2023, 08:13 PM	#6
Qsilver7 Major General 4448 Rep 7,489 Posts Drives: F06 650ix GC / F15 X5 50i Join Date: Oct 2016 Location: Indiana, USA iTrader: (0)	Yes…it is the “rotor cap”…which is mounted to the wheel hub…but that part of the rotor doesn’t have anything to do with the active part of braking. Thanks to the posts above that brought better clarity to what I was trying to say. __________________ 2015 F06 650ix Gran Coupe`(Moonstone/Cohiba Brown)\| 2014 F15 X5 50i MSport (Space Gray/Mocha) Become a BMW CCA member! Click HERE to join and feel free to use my BMW CCA member #191509 as a referral.
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10-16-2023, 10:15 AM	#7
Opie55 Colonel 1195 Rep 2,908 Posts Drives: '15 650i Convertible Join Date: Apr 2018 Location: US iTrader: (0)	As you know, the picture you posted is so out of focus it does not do us any good. While it is true that defects in the rotor hat where the wheel mounts will not affect braking performance per se, that does not mean that defects will have no effect at all. That surface needs to be flat or your wheel may wobble a tiny bit. It does not really matter how deep a gouge or scratch is, what matters is where the material is that used to be where the gouge now is. If you hit a flat piece of aluminum with a hammer or chisel, you will typically raise up the edges around the resulting dent. It's the raised edges you need to worry about. You should put some sandpaper around something flat and sand any raised areas down.
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