Rear brake discs

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Emmanuel M6
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Rear brake discs

Post by Emmanuel M6 »

Greetings all hope you and your cars are well. Just a piece of advice please from anyone kind enough who has the time please; I bought some rear brake discs for my m a while back ready for mot in March. Some moisture must have got to one of them as it has a few surface rust spots on it. May I take advice on what to use to remove them please? Thanks in advance. Peace.
Emmanuel M6
1985 M635csi
Location Corby Northants, previously London U.K.
wattsmonkey
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Re: Rear brake discs

Post by wattsmonkey »

Get a wire cup brush on them!

Hope all's good with you, hope we'll meet up in 2017,

Rob
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dwcains
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Re: Rear brake discs

Post by dwcains »

Just drive the car. I'm living the the humidity of south Florida, and if I don't drive one of the cars for several days. sometimes the brake pads get rusted to the rotors and I get a big "clunk" sound as the car moves and they become unstuck.
Dean
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Brucey
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Re: Rear brake discs

Post by Brucey »

the working parts of brake discs always rust if given a chance to. If the rest of the disc is prone to corrosion, you could do like Ron has done; IIRC he had his discs given a passivated zinc finish. This wears off the braking surfaces quite quickly (and they can corrode again) but it does deter corrosion elsewhere on the discs.

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dwcains
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Re: Rear brake discs

Post by dwcains »

True - I always buy discs that are plated, so you don't see ugly, rusted hats and edges through the wheels..
Dean
Lutz, FL

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'87 Spider Veloce
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Emmanuel M6
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Re: Rear brake discs

Post by Emmanuel M6 »

Greetings and thanks to everyone who responded to my enquiry. I have a wire brush for them:-) Yes Rob hope to see you in 2017 and you as well Bru6e. Peace and good driving .
Emmanuel M6
1985 M635csi
Location Corby Northants, previously London U.K.
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BA in CT
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Re: Rear brake discs

Post by BA in CT »

I always paint the rotor and other items that like to corrode ;-)

Its amazing how far some black spray paint will go...

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Emmanuel M6
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Re: Rear brake discs

Post by Emmanuel M6 »

Thanks for your response which is most appreciated. I have cleaned the rotors with a cup brush and that's taken the rust off. So do you actually spray the discs themselves and do you use normal spray paint? I assume it doesn't affect braking. Peace.
Emmanuel M6
1985 M635csi
Location Corby Northants, previously London U.K.
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dwcains
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Re: Rear brake discs

Post by dwcains »

I'd use a high-temp spray paint, and there are no worries if you get it on the friction surfaces, as it will get scraped off the first time you apply the brakes. Color choice is yours, but typically you'll see mate black or silver, whether it's paint or plating.
Dean
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Brucey
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Re: Rear brake discs

Post by Brucey »

FWIW not every bake pad material will handle contamination with every type of paint. If you do paint the bells, I think it is best to mask off the actual braking surface. It isn't exactly difficult to do this, either.

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m6doc
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Re: Rear brake discs 1988 M6

Post by m6doc »

I bought my M6 as second owner in 2005. Shortly before I purchased the car, the original owner upgraded the brakes to the e34 M5 US Spec front rotors but upgraded the rear rotors to the e34 M5 Euro Spec rotors from the 3.8L Euro version in OEM size 328mm x 20mm vented. I have owned the car now for 12 years and after 50 miles, I need to replace the rear rotors and pads. I would like to upgrade the discs all around to a performance rotor that are slotted but can only find the equivalent aftermarket to fit the front US Spec.

I can not find a aftermarket performance rotor of any kind in that size of 328x20. This rotor was also used on the 850Csi but still can not find a aftermarket sport rotor that is drilled, slotted, etc in that size.

If any one knows of a european supplier that might be able to help me and point me in the right direction, that would be great !

Thanks --

Jeff
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tschultz
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Re: Rear brake discs

Post by tschultz »

That is part of the problem of having the rare 3.8L E34 brakes-- parts are hard to find and very $$$.

If I were you I would go with standard rotors. What sort of driving are you doing to warrant a performance brake rotor? I'd actually be worried about the brake balance with those large rears. I'd suspect in an emergency the ABS is coming on (due to the rear) before the actual limit of your front brakes.
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Re: Rear brake discs

Post by m6doc »

yeah, looks like I will have to either get a OEM rotor for the rear from BMW or switch the rear out for a US Spec e34 M5 rotor but that would also require switching the rear calipers and carrier arms too. Again ... $$$.

Doing research on the brake bias from the larger rear but not sure it is a problem as although the disc itself is bigger, the stopping power of the larger rotor is diminished by having a single piston caliper and somewhat small disc surface area even though it is a ///M Caliper. In the 50K miles I have driven it with a few track events and "spirited driving" events, I have not noticed any issues including any premature ABS issues.

Thanks for the input.
All the best -- Jeff
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