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E90/E91/E92/E93 (2006 - 2013)
The E9X is the 4th evolution of the BMW 3 series including a highly tuned twin turbo 335i variant pushing out 300hp and 300 ft. lbs. of torque. BMW continues to show that it sets the bar for true driving performance! -- View the E9X Wiki

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Old 05-20-2013, 10:43 PM
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Mk23 Mk23 is offline
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Can you get rotors resurfaced? And if so do they need new brake pads after?

I essentially have what appears to be a brake pad burn in on my rotors (which are fairly new too). I think the local dealership did it as I was told the service manger test drove the car and applied lots of braking to heat up the brakes for an issue I was having once the brakes were hot. So I think he braked hard down to a dead stop on brand new pads and it burned into the rotor. At least that's what it looks like. I have the etch in on both front rotors and if you run your fingers along the rotors, the rotors are smooth and then when you hit the spot it is rough. I've been having a squeal problem and I got ceramic pads and just happened to notice this on the rotors when cleaning the hubs.

Anyone know if I can get rotors resurfaced? And do I need new pads after it is done? Or can I re-bed in the brake pads I was about to put on? I can wait to put on my new brake pads if need be.

P.s. Sorry for the typo in the title, don't know how to correct it. Mods, any help?

Quick off-topic question, do the inner wheel hubs need grease? (the one that the wheel goes around and the cap covers up) I just cleaned up my hubs and am wondering if I cleaned off grease and if it needs it. FYI I get a lot of rust living in Florida, if that helps.
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Last edited by Nordic_Kat; 05-21-2013 at 04:51 AM. Reason: request of OP
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  #2  
Old 05-21-2013, 03:17 AM
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CALWATERBOY CALWATERBOY is online now
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Quote:
Originally Posted by Mk23 View Post
I essentially have what appears to be a brake pad burn in on my rotors (which are fairly new too). I think the local dealership did it as I was told the service manger test drove the car and applied lots of braking to heat up the brakes for an issue I was having once the brakes were hot. So I think he braked hard down to a dead stop on brand new pads and it burned into the rotor. At least that's what it looks like. I have the etch in on both front rotors and if you run your fingers along the rotors, the rotors are smooth and then when you hit the spot it is rough. I've been having a squeal problem and I got ceramic pads and just happened to notice this on the rotors when cleaning the hubs.

Anyone know if I can get rotors resurfaced? And do I need new pads after it is done? Or can I re-bed in the brake pads I was about to put on? I can wait to put on my new brake pads if need be.

[1] Just sand paper or, better, emery cloth them boys. There. Your brake pad residue, result of dealer bedding in your brakes, is gone. Now you start over, conditioning the brakes. Didn't take off one rotor.

[2] You mean grease on the outside surface? Good Lord no! All you need for poor brakes is migration of grease to the swept area. And wasn't there a thread on rotor rust resolution just yesterday right here in the forum? Check it out....
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Old 05-21-2013, 04:01 AM
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You can use anti-seize on the hubs. Follow CWB's advice...or just drive the car and it will smoothe out after a couple of weeks. This thing is common with tracked cars that don't use track pads once they get fast enough.

It sounds like the tech didn't cool the brakes off before applying them for an extended period.
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Old 05-21-2013, 06:04 AM
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"Anyone know if I can get rotors resurfaced? And do I need new pads after it is done? Or can I re-bed in the brake pads I was about to put on? I can wait to put on my new brake pads if need be."


Yes, you certainly can get the rotors resurfaced. All rotors come with two specs, one is the minimum thickness to which they can be machined and the other is the discard thickness. Any thinner than that and they go on the scrap metal heap. Anyone who tells you BMW rotors cannot be machined is wrong. Including the dealer. Of course they have to be in machinable condition and that may be a small judgement call. When they are machined they must be done to a non-directional finish of the proper RMS smoothness.
If you change the rotors you absolutely should change the pads.

Note: Your squeal is NOT being caused by the etching on the rotor, that'll only cause a pulsation from grip/no grip/grip. The squeal is caused by what's happened to your pads. For the record, squeal rarely results from the contact of the pad with the rotor*. It is caused by the vibration of the steel back of the pad against the brake frame/caliper assembly. Knowing that is step one to getting rid of squeal.
*Certain performance brake pads come with squeal built in. Every time you apply the brakes it lets a little bit of squeal leak out. This tells you that you are not braking hard enough often enough. Ask ///M-rated.
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Old 05-21-2013, 08:40 AM
jburke4689 jburke4689 is online now
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I replaced the pads and rotors on my 335i. I noticed the the rotors appeared to be constructed from 3 separate pieces. Essentially a one piece rotor with the surfaces that the pads clamp on attached somehow. The brand new rotors OE rotors were very, very close to minimum thickness and the one's I replaced were below minimum thickness so I couldn't resurface them. The car had 82k miles on the original pads and rotors. I guess my point is that if you use up the entire pad you are unlikely to have enough meat on the rotor to resurface it. If they are fairly new, be careful on how much you remove so that you don't get below discard thickness.
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Old 05-21-2013, 01:32 PM
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Just to clarify I had new rotors installed about 4 months ago. I have just finished cleaning up my hubs and calipers from rust, and was concerned that a possible burn in from the pads on the rotors was causing a squeal that has been ongoing for the better part of a year. Dealership finally gave up and told me tough luck after my warranty ran out. They did throw new rotors pads and greased all the suspension. I also specifically asked them to take off the rotors and check and clean any rust behind them where they might contact the brake dust shield. I now have new ceramic pads I am about to put on but was concerned I might have to resurface the rotors first.

So just use sandpaper or emery cloth? Should I sand them in a circular pattern (with the grooves)? Could I just sand the area that is rough or should I do the whole rotor surface?

I also forgot to add that the calipers kind of grab the rotors when they come around to that rough spot. (when jacked up)
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Last edited by Mk23; 05-21-2013 at 03:23 PM.
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Old 06-03-2013, 09:05 PM
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Would just like to give an update on what I did and the effect it had.

I sanded the rotors with 120 grit sandpaper using lots and lots of brake cleaner while doing it. It seems to have worked too. No more squeal, and brakes feel great!

Thanks for the help guys!
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