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Discussion Starter #1 (Edited)
Hi all,



I'm in the process of building a CB175 into a vintage race/track bike, targeting the 200GP+ AHRMA class. It's a long, slow process, and I'm learning everything as I go. The front end as it's being built is a CB200T fork mated to a '74 XL175 triple tree staying at the original 31mm. It's a straight swap without any stem modifications.

My question is about the front hub/brake. I have the original CB175 brake, but I also have a '67 CB77 36-hole front brake from a previous still-born CB350 project.

Is the added weight of the CB77 brake worth the increased braking performance? Would I be better off using a smaller CB350 or even the stock CB175 or CB200T front brake for racing?


Also, while I'm asking about drum brakes, who is doing re-linings and arcing currently? Seems like a lost art that is only done by a few. Not really worried about a long lead time—I hve a long lead time, myself. :)



Doug

Current status of my race build...
 

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Discussion Starter #4
FWIW: The riders I know who do that kind of racing, they don't seem to use the front brakes very much.
I figured as much. I have heard front brakes discussed in other threads and other groups, and a few GP200 guys mentioned Water Buffalos and other large bike front brakes, so I was wondering out loud. With Blackhawk, Gingerman and Road America in my sights, I'll be dealing with heavy braking zones or at least shorter tracks.



I found my CL175 front brake to be sufficient, but I'm not one of the top tier guys.
I don't aspire to be one of those guys, either, I just want to have fun and race with someone. I don't like being down on equipment, though, so that's one of those reasons why I wonder if this is the right path.
 

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I ran the stock front end with tapered bearings and stock wheels and brakes. The only place I really felt lacking was top end speed.

Unless you do some serious motor work, those guys will get away from you.
 

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Discussion Starter #7
I'll be at Blackhawk as a spectator if we go to phase 4 like we should by the end of the week. Looking forward to getting back out there, even if it's just as a bystander.
 

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I'll be at Blackhawk as a spectator if we go to phase 4 like we should by the end of the week. Looking forward to getting back out there, even if it's just as a bystander.
Race!
You are just cheating yourself out of the opportunity if you don't.
Buy the competition license up front, then you have no excuses when the time comes and afterwards you will be thankful that you didn't just go to watch.
 

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Discussion Starter #9 (Edited)
Race!
You are just cheating yourself out of the opportunity if you don't.
Buy the competition license up front, then you have no excuses when the time comes and afterwards you will be thankful that you didn't just go to watch.
I'll get there eventually. Need to build a bike first. Then the AHRMA school, which I believe is that weekend, as well. It's my target goal. I'm just thrilled that they are finally back at Blackhawk Farms.
 

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GP200+ class sounds pretty cool, how much can you modify your bikes in that class, is the sky the limit? That would be good considering the bike you are racing ;)
 

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If you register for 200GP you can add the CB160 Lemans start race for $20. That's a crazy good deal. (Yes you're eligible to race that class).
 

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Stock brake would probably be fine as majority of courses are used by 180mph+ 'superbikes' so have very few if any hairpin bends or really tight chicanes for a sub 90mph bike.
The CB72/77 brake is real nice looking though but a CB450 is slightly lighter (both are same inner diameter) biggest issue with 450 brake is 40 spoke instead of 36. (40 hole rims way more expensive) CB250/350/360 may be easiest compromise? (they are all same inner dia but have some variations on design. Haven't weighed CB360 TLS but I think it's slightly lighter than earlier 350 twin? The design of brake plate is slightly different and may be easier to fit into narrower forks? 360 brake plate doesn't fit 350 hub without modifications. (different webbing on hub and brake plate) If you can find one, Suzuki GT185 TLS could be a good option?
I don't think stock CB200 brake is eligible for AHRMA, AFAIK, they only ever came with the cable disk ?
If you want to go fast, the best thing to do would be fit widest rims allowed and the stickiest tyres, plus, make sure you have at least a 50 degree lean angle clearance (basically, forget the brakes and lean further) Hailwood/Surtees riding style really helps with low powered bikes, hang off the side to act as an 'air brake' but otherwise stay centered and lean further.
 

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Discussion Starter #14
Stock brake would probably be fine as majority of courses are used by 180mph+ 'superbikes' so have very few if any hairpin bends or really tight chicanes for a sub 90mph bike.
The two local tracks are Blackhawk (with a slow chicane after a fast carousel) and Gingerman (with a handful of low speed 90° corners). Outside of Road America, these will be my home race tracks.


The CB72/77 brake is real nice looking though but a CB450 is slightly lighter (both are same inner diameter) biggest issue with 450 brake is 40 spoke instead of 36. (40 hole rims way more expensive) CB250/350/360 may be easiest compromise? (they are all same inner dia but have some variations on design. Haven't weighed CB360 TLS but I think it's slightly lighter than earlier 350 twin? The design of brake plate is slightly different and may be easier to fit into narrower forks? 360 brake plate doesn't fit 350 hub without modifications. (different webbing on hub and brake plate) If you can find one, Suzuki GT185 TLS could be a good option?
I figured the CB77 brake was too large—it even looks large on the CB550 front end I have it sitting on currently. It's just BIG. A few racers have convinced me that the CB350 front brake is a good compromise between the CB175 front drum and the big CB77 front drum. All 36-hole, and now all of them are sitting on my workbench.

The front end of the build I think will consist of these parts:
  • 1970 CB350 front drum & brake hub
  • 1979 CM185T 31mm fork legs
  • 1974 XL175 31mm triple tree
  • RaceTech springs & emulators
I think this is the best combo of performance, cost and availability. I have a set of CB200T fork legs, but the stanchions are pitted, rusted and bent, and clean ones are pretty much non-existent in the wild. FbF new ones are $400, which is a bit aggressive.

We'll see how this pans out. Thanks for the advice, guys! Much appreciated.
 
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