EBC Rotors and tolerances

JOHN SOLIDAY johnsoliday at msn.com
Wed Mar 12 22:49:41 PDT 2008

IMHO I would not have sanded the rotor.  These are not cast iron (I'm pretty sure) and you might have polished off the stainless plating.


> Date: Wed, 12 Mar 2008 11:03:48 -0700
> From: steven at bixbys.net
> To: gpzlist at micapeak.com
> Subject: EBC Rotors and tolerances
> Hey, guys, I got my first ride of the......  day, today! :)   (I have
> about 1500 miles so far this year, give or take.)
> So anyway, by sheer negligence, I failed to notice how worn the pads
> were on my wife's Ninjette (250) rear brake, and it thoroughly trashed
> the rotor.  Really ugly!
> So we ordered an EBC rotor to fit, from their basic "MD" line since
> it's the only non-OEM rear rotor I can find for the Ninja 250
> *anywhere*.  After a fumble where the shop actually ordered a front
> rotor, we did get a replacement rotor.  (I've gotten rotors off ebay
> before that were worse than the ones I wanted to replace, so I gave up
> on that approach.)
> So I did what I thought one was supposed to do, and went over the
> rotor lightly & evenly with an orbital sander to knock off the glaze,
> before installing it.
> She rode it one day after that and said the pedal pulsed fairly
> heavily, so I got out my trusty caliper (cuz I couldn't find my
> less-trusty micrometer) and measured a variation of 4.42mm to 4.50mm,
> on four evenly spaced spots on the rotor.
> However, I'm not sure if that's within normal tolerances for a rotor,
> does anyone know?   I'm sure it's not given the amount of pulsing the
> brake does.
> I also wonder if I made a mistake in deglazing the rotor surface
> before I installed it - I used the sander in smooth circles for about
> 10 seconds a side, using about 150-grit paper.  I don't *think* that's
> enough to remove 0.08mm of material on a side, but if I screwed this
> up, then... I won't do it next time.
> Whaddya all know?

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