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02-23-2015, 02:07 PM | #1 |
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Shaving Rotors
Do any of you guys shave rotors. It's about time for new pads and rotors but they are thick enough where they can be shaved. Anybody have an opinion on shaving rotors? Not sure what to do.
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02-27-2015, 06:09 PM | #2 |
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Advised from my local German auto mechanic "these rotors are not to be cut. If someone were to offer to do that run the opposite way fast"
I don't remember why but that's what I'm told... GL |
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02-27-2015, 06:14 PM | #3 |
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If BMW has a published minimum thickness I'd be fine with it.
You say "they are thick enough" but what leads you to that belief?
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02-27-2015, 07:09 PM | #4 |
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Just a thought... The front rotors are two piece and allow for thermal expansion. You can see the pins around the rotor hat (about the size of a dime) that hold the rings in place. Just the slightest amount of play between the ring and hat when resurfacing the rotor could affect runout. I'm guessing this is why it is not recommended?
I don't think you would have an issue with the rears since they are one-piece. |
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02-28-2015, 07:09 PM | #6 |
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Thinner Rotor= more prone to warping. They are cheap enough. Just buy new ones.
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02-28-2015, 11:00 PM | #7 |
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Pretty sure that's just to tell you when they are too warn to reuse, not a how much you can cut thing. Replace them if they are scored or too thin.
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03-01-2015, 07:47 AM | #9 |
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No German auto shop (in Germany) even offers shaving rotors here. Just replace them.
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03-01-2015, 11:18 AM | #11 |
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I understand where everybody stands on it but does anybody have first hand experience with it. They take off not even a half a millimeter. My rotors are all about 3mm above minimum thickness that BMW published. I say first hand experience because most of these replies are just hearsay. "So and so told me". I don't disagree with not going cheap on brakes but why spend 500 bucks on new rotors when you could shave less than a half a millimeter off and not be able to tell a difference?
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03-01-2015, 11:25 AM | #12 |
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In all honesty, pig farmers reply was the only reply worth reading, no offense... I will end up purchasing new brake rotors but I definitely think someone should look more into resurfacing brake rotors on our vehicles
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03-01-2015, 12:00 PM | #13 |
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Obviously it's recommended to replace rotors along with pads. But if you prefer to machine them make sure it's w/in spec.
There is usually a min thickness and a 'min. thickness to machine' |
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03-01-2015, 12:41 PM | #14 |
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I don't see why anybody would go to the effort. It's more hassle than just fitting new ones. Perfect chance to upgrade too. I just fitted ECS drilled & slotted rotors all round, with EBC Red Stuff pads & HEL Performance lines. I could not be happier, the improvement over stock rotors & pads is like night & day, and my old rotors/pads were not even worn out.
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03-01-2015, 11:38 PM | #15 |
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Guess I'm in the minority, but mine have been turned (same as "shaved" I guess). Less than $20 each and they still do great on the track. In fact, I have another set of fronts that go back on with the street pads when I change them; I don't have to bed either set anymore. I know lots of track addicts that have used turned rotors for years and I've never heard of a single issue. Nothing wrong with buying new ones, but I'd keep the tire/gas money!
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03-02-2015, 10:01 AM | #16 |
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Resurfacing rotors is in no way "ghetto."
If BMW publishes a minimum thickness I say go for it. That in my mind means a competent engineering team did the work to confirm a safe thickness from structural standpoint. Just realize they'll wear further from when you have them machined as you use them. If you'll end up hitting the minimum point before your new pads are worn it may not be worth the bother.
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03-02-2015, 10:32 AM | #17 |
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Awesome, thanks for the replies. Does anyone know the thickness of BMW rotors when they are brand new?
As of right now mine measures; Front drivers side-25.45 Front passenger side-26.17 Rear drivers side-23.79 Rear passenger side-23.73 Last edited by tglazed; 03-02-2015 at 10:37 AM.. |
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03-02-2015, 10:50 AM | #18 |
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95% of the time here at Acura we machine the rotors when we change pads. Unless the brakes are not serviced on time/properly, the rotors are usually still above min. thickness for nearly the life of the vehicle.
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03-02-2015, 11:06 AM | #19 |
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Different metal composition. Pretty much the opposite at BMW. Even under the 4 year 50K free maintenance program they chuck the rotors on a pad change.
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03-02-2015, 01:18 PM | #20 | |
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Rear nominal 22 mm, minimum 20.4 mm I think you measured your rears incorrectly. |
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03-02-2015, 01:20 PM | #21 |
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Its the pads not the rotors. BMW rotors stay nice and shiny because they are continually being polished and turned into dust by the pads. All rotors are cast iron, with some hair splitting regarding carbon content.
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03-02-2015, 01:31 PM | #22 | |
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Also, the concentric texture of a turned rotor is not ideal. Rotor faces should have a random texture, hence new rotors are ground not turned. Turned rotors shouldn't be used "as turned", they should be given a random texture with a sanding disk. |
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