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Discussion Starter · #1 ·
I have a pair of old dual brake discs/rotors with over 1mm material left on them. I would like to use them on my 650 Eurosport build but I’m not sure how best to prep them. I have removed the surface rust with wire brush and emery paper and will paint the centres but should I have a machinist take 0.01mm off on a lathe or just leave as is and let new brake pads work the surfaces?

Before and after pics below

Automotive tire Light Bicycle part Gear Rim
Automotive tire Tire Tread Guitar accessory Wood
 

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81 Gl500i 83 CX650E
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I would sand them with a 220 or finer grit sand paper in the direction of rotation. They look in pretty good shape , only thing I would check is the side run out to make sure they are not bent. Seen to many rotors buggered up by trying to machine them, not as simple as it sounds.
Side note ,takes a while for new pads to seat themselves to the rotors.
Missed the second picture , looks good I would be using them.
 
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Are not motorcycle rotors usually ground rather than turned?
 
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CX500 Z 1978 , Rickman Polaris fairing, currently GL500 front, Ignitech etc. subject to change
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check : AFAIK these discs start out at 5mm, minimum (as stamped on the centre) is 4 mm. How did you measure more than 1 mm available?
 

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I only have rotors machined if they are out of round (causes wheel shake)or varying in thickness ,(which would cause brake pulsing) .
Grinding is the recommend process for bike rotors as they are made out of Stainless steel don't lathe cut very well, to long of a story why I know that.
Just a note, been an Auto mechanic for over 42 years and have done more brake jobs then I can count. If they run straight use them. Cheers
 

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CX500 Z 1978 , Rickman Polaris fairing, currently GL500 front, Ignitech etc. subject to change
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made out of Stainless steel
a magnet will stick to the ones I've got (tried one to be sure, single pot type no holes), always thought these "old" original types were simple iron, stamped or even cast ?

I know at least some more modern ones are stainless steel.
 

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I have a pair of old dual brake discs/rotors with over 1mm material left on them. I would like to use them on my 650 Eurosport build but I’m not sure how best to prep them. I have removed the surface rust with wire brush and emery paper and will paint the centres but should I have a machinist take 0.01mm off on a lathe or just leave as is and let new brake pads work the surfaces?

Before and after pics below

View attachment 213383 View attachment 213384
If you need new tires while you are doing the brakes I have 2 brand new ones for a Eurosport. They are the best...Bridgestone Battlax.Baggo
 

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Discussion Starter · #13 ·
If you need new tires while you are doing the brakes I have 2 brand new ones for a Eurosport. They are the best...Bridgestone Battlax.Baggo
Thanks Baggo but hi have scrambler tyres on this build. I also have 500E cafe racer which is shod with Bridgestone Battlax though. I’m also in the UK so shipping would not be worthwhil.
 
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