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BRITISH COLUMBIA CLASSIC MOTORCYCLE CLUB
20757 Posts in 574 Topics by 475 Members
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| | |-+  Brake rotor resurfacing.
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Author Topic: Brake rotor resurfacing.  (Read 214 times)
Galactica
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« on: March 24, 2025, 03:30:19 PM »

So, my CB750K5 is a pretty nice runner.  But it doesn’t stop at all well.  Actually kinda scary.  I’ve replaced/rebuilt the front brake from top to bottom.  Except for the rotor.  It’s actually quite scored.  I don’t have any experience with how much braking would be improved by resurfacing or replacing the rotor. 

In your considered opinion, would braking be significantly improved by resurfacing or replacing/replacing the rotor.  I can get an aftermarket rotor for $328.30.  My understanding is that, because the configuration of these old motorcycle rotors, it’s difficult to turn them.
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Past rides:
75 Honda CB750K5
80 Suzuki TS250
 ? Yamaha Maxim 550
73 Z1 900
76 Kz900 A1
77 Kz1000 A1
78 Kz1000 B2 Ltd
79 Kz1000 B3 Ltd
80 Kz1000 C
99 Triumph Tiger 900
84 Honda VF750 Interceptor
77 Honda CB750


Current ride:
2019 Yamaha Tracer900

Current project:
1975 Honda CB750K5
Galactica
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« Reply #1 on: March 25, 2025, 09:09:18 AM »

Posted this in another thread as well:

Damn the torpedos.  I did a bit of reading about resurfacing these rotors.  It seems you only get about 20 thou to remove from each side.  And because of the hard stainless material, it’s recommended to grind rather than turn.  So I bit the bullet and ordered a new rotor.  Could have saved some $ by ordering through the US and shipping to a US address.  But considering current border issues, the ship $ saved wouldn’t be worth the hassle.  And I’ll have it in hand from the Ontario supplier early next week.
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Past rides:
75 Honda CB750K5
80 Suzuki TS250
 ? Yamaha Maxim 550
73 Z1 900
76 Kz900 A1
77 Kz1000 A1
78 Kz1000 B2 Ltd
79 Kz1000 B3 Ltd
80 Kz1000 C
99 Triumph Tiger 900
84 Honda VF750 Interceptor
77 Honda CB750


Current ride:
2019 Yamaha Tracer900

Current project:
1975 Honda CB750K5
Galactica
1000 Class
******
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Posts: 4730



« Reply #2 on: March 25, 2025, 01:12:51 PM »

When I get the new rotor installed, and weather permits a ride, I’ll be able to report differences, if any, in braking performance between old and new.
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Past rides:
75 Honda CB750K5
80 Suzuki TS250
 ? Yamaha Maxim 550
73 Z1 900
76 Kz900 A1
77 Kz1000 A1
78 Kz1000 B2 Ltd
79 Kz1000 B3 Ltd
80 Kz1000 C
99 Triumph Tiger 900
84 Honda VF750 Interceptor
77 Honda CB750


Current ride:
2019 Yamaha Tracer900

Current project:
1975 Honda CB750K5
hardrockminer
BCCMC Star (5K)
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« Reply #3 on: March 26, 2025, 03:48:16 AM »

Was the rotor worn below the acceptable limit?  I've never found one that was worn that badly.
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Past rides include a 1973 Suzuki GT380 & a 1975 Kawasaki Z1B

I currently ride a 1975 Kawasaki Z1B - Classic Plated
I also ride a 1980 Kawasaki KZ 1000 LTD - Classic Plated, and a 2006 Honda Goldwing with a Daytona 2+2 sidecar

My Sweetums rides a 2019 Suzuki DR650
Galactica
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« Reply #4 on: March 26, 2025, 03:49:18 PM »

Tons of material available for removal.  Original thickness is 7mm and despite the grooves, that’s what it still is.  Minimum thickness is 6mm.  So lots of room.  By all accounts though it should probably be ground on something like a flywheel grinder.  Apparently, because of the hardness of the stainless steel, a lathe can tend to chatter, and the tools must be really sharp and won’t stay sharp very long. 

In any case, I have a new aftermarket rotor en route.
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Past rides:
75 Honda CB750K5
80 Suzuki TS250
 ? Yamaha Maxim 550
73 Z1 900
76 Kz900 A1
77 Kz1000 A1
78 Kz1000 B2 Ltd
79 Kz1000 B3 Ltd
80 Kz1000 C
99 Triumph Tiger 900
84 Honda VF750 Interceptor
77 Honda CB750


Current ride:
2019 Yamaha Tracer900

Current project:
1975 Honda CB750K5
Twisted_Twin
BCCMC Star (5K)
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15/16ths of the world uses the metric system.


« Reply #5 on: March 26, 2025, 04:35:14 PM »

Ross,

The last ones I cut for you were done on a lathe. Stainless wasn't a problem and the lathe has pucks that ride on the disc to stop any chatter.
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It's important to feel comfortable in your own skin because it's illegal to wear someone else's.
Bucko
1000 Class
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Posts: 2538



« Reply #6 on: March 27, 2025, 10:17:46 AM »

Our buddy Murry at Modern used to grind rotors - not sure if that's still the case or not. 
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Galactica
1000 Class
******
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Posts: 4730



« Reply #7 on: March 27, 2025, 10:52:11 AM »

Our buddy Murry at Modern used to grind rotors - not sure if that's still the case or not. 

Hey Dave,

Did you sell any of your bikes?
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Past rides:
75 Honda CB750K5
80 Suzuki TS250
 ? Yamaha Maxim 550
73 Z1 900
76 Kz900 A1
77 Kz1000 A1
78 Kz1000 B2 Ltd
79 Kz1000 B3 Ltd
80 Kz1000 C
99 Triumph Tiger 900
84 Honda VF750 Interceptor
77 Honda CB750


Current ride:
2019 Yamaha Tracer900

Current project:
1975 Honda CB750K5
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