My MC18 rotors measure 276mm and I have a set of CBR600 (F3) EBC pro lite race rotors, they bolt right on but measure 293mm. I did read that NC30 lower fork will allow to mount NC30 rotors, but not sure what size they are. If anyone knows the diameter I would greatly appreciate it. I can modify things to work with adapter plates etc, but prefer not to do this

I don't want to use CBR600 fork because it uses 2 inferior piston caliper, I am however shortening the CBR cartridge to be fitted in to my MC18 fork!

NC30 discs should be 296mm, as i think should be the cbr600 ones you have, also the same size are, VFR750 94-97, CBR900 94-97, NC35, and some CBR400, these should all bolt to your NSR wheel.
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So if I get a NC30 or NC35 forks or just lowers it should allow for original NSR calipers to be mounted with stock MC18 wheel and CBR rotors?

No, you also need the NC calipers, or you need to machine the NSR calipers very slightly, or they will bind on the 296mm discs.

The castings look the same, but they differ very slightly. You will see as soon as you try to tighten the NSR calipers to the forks with the big discs fitted!
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Andy.
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Andy's right, it's an absolutely tiny amount and you'd swear looking at them mc21 and nc30 calipers are the same, but they're not.
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Great info, Thanks!

I might just leave it as is for now, lots of trouble for extra 10mm of braking. NC30 are rare in US and shipping fork lowers from UK will cost more than I care to spend at the moment, will be browsing the evilBay, something might come up but I will not make any changes for now

Properly serviced NSR brakes really are very good since the bike is so light. Perfectly capable of waving the back wheel in the air!
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Good to know Dave, Thanks!

I have a caliper rebuild kit coming form MM, once I have the swingarm of choice fitted will know the rear line length and order HEL lines, also have a radial master cylinder to install, I'm sure it will brake fine. When I raced the Hawk (Bros for you Limey Bastards) I had CBR600 front end fitted with crappy 2 piston calipers and those EBC 293 mm cast iron rotors (which are still sitting at my shop 10 years later) Fitted with EBC HH pads they were good enough to do a 100 mile per hour "endo" if I wasn't careful at the end of the straights, so I wanted to re-purpose them just because I already have them

Sorry to resurrect this old thread, but I have a question. Although as stated the NC30 and MC21 calipers look the same (but are slightly different in terms of fitting), do they use the same pistons, seals and pads?

Thanks,

Al.
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Cheers....

Al

Bikes:
GPZ900
NC30
NSR250SE
RGV250 vj22

It seems they do have same everything but the mounts, also CBR900RR has same calipers and to me looks like parts are interchangeable.

BTW, I loosely mounted CBR600 wheel and rotors on to NC30 fork with MC18 calipers and everything lined up, didn't see any clearance issues. Will try it again once NSR wheel is back from powder coat.

oops, I just realised the thread was about the MC18, not the MC21. Sorry.

However, if someone can confirm the following I would appreciate it.

The MC18 has the same size caliper pistons as the NC30: 25mm and 30mm
The MC21 has the same size caliper pistons as the NC35: 27mm and 30mm

Thanks again.

Al.
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Cheers....

Al

Bikes:
GPZ900
NC30
NSR250SE
RGV250 vj22