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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Suspension | Brakes | Chassis > Pad contact on rotor after new install?



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      01-08-2023, 03:16 PM   #1
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Pad contact on rotor after new install?

Hey guys,
First post here. I just replaced pads and rotors on my E91 328xi wagon. I bought this exact kit from FCP euro: https://www.fcpeuro.com/products/bmw...6ktfr4#fitment

I installed the rear pair yesterday, everything went smooth enough. However after going for the initial drive I noticed the coating has not been removed from the inside part of the rotor. My guess is the pad is not fully contacting the rotor?





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I don't imagine the pads are in wrong as the tabs seem to only fit one way, and I copied how the previous pads were set in the caliper. Did I do something wrong? Is this typical? Note it is like this on both sides, so if I installed correctly I did the same on both sides.

Thanks
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      01-08-2023, 03:30 PM   #2
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So you have uneven wear….
Did you check the guide pins move nice and easily and smooth?
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      01-08-2023, 03:53 PM   #3
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Quote:
Originally Posted by Runnin'Rich View Post
So you have uneven wear….
Did you check the guide pins move nice and easily and smooth?
I neglected to check, but I did put some lube on them before sliding them back and and tightening them down when re-installing.

I think my next step will be to go back and re-lube everything.
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      01-08-2023, 04:07 PM   #4
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Silicon brake grease is what I use.
However I’ve seen on TIS before to only clean the guide pins and not apply any grease.
You may not have hit the brakes hard enough to rub off the coating. I imagine one pad would contact the disc first and then the other side. The less friction in the caliper and guide pin system the more even the wear will be.
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      01-26-2023, 12:02 PM   #5
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Quote:
Originally Posted by Runnin'Rich View Post
Silicon brake grease is what I use.
However I’ve seen on TIS before to only clean the guide pins and not apply any grease.
You may not have hit the brakes hard enough to rub off the coating. I imagine one pad would contact the disc first and then the other side. The less friction in the caliper and guide pin system the more even the wear will be.
That's what I was thinking. Maybe you need to hammer the brakes and really set in the pads. It's part of the brake in process (pun intended). I've seen most guys to 30, 45, and 55mph FULL brake stop. I want to know it's installed correctly before I actually panic brake in traffic.
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      01-26-2023, 01:04 PM   #6
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I would not "hammer" the brakes hoping to get more pad contact with the rotor. I have always done about six passes at about 35MPH and not come to a complete stop, overheating the brakes during bedding may warp the rotors. If the install is correct, the pads will soon wear that area of the rotor.
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      01-27-2023, 09:46 AM   #7
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Quote:
Originally Posted by Jaronbwall View Post
That's what I was thinking. Maybe you need to hammer the brakes and really set in the pads. It's part of the brake in process (pun intended). I've seen most guys to 30, 45, and 55mph FULL brake stop. I want to know it's installed correctly before I actually panic brake in traffic.
This is not the right procedure for bedding brakes. Do not come to a full stop!

I normally do 8 repetitions of 60mph then brake without engaging abs down to 15mhp, then accelerate to 60mph and repeat.

I do warmup the brakes first with light braking and then do the procedure.

Do it at night with no traffic. Make sure you have a nice clear stretch of the road.

Never at any time during the bedding procedure should you come to a full stop with brake pads engaged to the rotor.

Last edited by Wolf 335; 01-30-2023 at 07:09 AM..
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      01-27-2023, 09:55 AM   #8
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Quote:
Originally Posted by adracing View Post
Hey guys,
First post here. I just replaced pads and rotors on my E91 328xi wagon. I bought this exact kit from FCP euro: https://www.fcpeuro.com/products/bmw...6ktfr4#fitment

I installed the rear pair yesterday, everything went smooth enough. However after going for the initial drive I noticed the coating has not been removed from the inside part of the rotor. My guess is the pad is not fully contacting the rotor?


I don't imagine the pads are in wrong as the tabs seem to only fit one way, and I copied how the previous pads were set in the caliper. Did I do something wrong? Is this typical? Note it is like this on both sides, so if I installed correctly I did the same on both sides.

Thanks
Give it a bit of time, it will level off.
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      01-27-2023, 08:34 PM   #9
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Sliding calipers brakes will always do this. People don’t notice because most rotors don’t come coated on the brake surface. Nothing wrong. Continue using your car without worry.
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      01-29-2023, 02:04 PM   #10
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Quote:
Originally Posted by Wolf 335 View Post
Give it a bit of time, it will level off.
+1

Fitted new discs and pads myself recently and for a few weeks only about the third of the braking area was being swept. But eventually the pads fully bedded in and all's well...
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      01-31-2023, 07:25 AM   #11
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I shouldn't use the term "hammer" but yeah you need to set in the pads.
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      02-03-2023, 10:35 AM   #12
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Does this same procedure work for all pad materials (i.e. ceramic) or should ceramic pads be bedded differently? I don't like dusting and want to consider ceramic style pads on existing rotors.
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      02-08-2023, 06:32 PM   #13
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Make sure these two prongs are seated at the holes they are supposed to go into and not sitting proud:
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      02-08-2023, 06:35 PM   #14
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Quote:
Originally Posted by BlackNight28 View Post
Does this same procedure work for all pad materials (i.e. ceramic) or should ceramic pads be bedded differently? I don't like dusting and want to consider ceramic style pads on existing rotors.
No that's kind of the thing about everyone saying how to bed pads. I would just refer to the instructions of your brakes pads. In fact some pads even have no bed in, the Akebono are like that I believe although they do have a "break in"/not go super hard on them for X miles.
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