Triumph front end project using CB750 hub?

[calal]

I'm new to this forum and not a CB750 owner although I have a couple of later Hondas, an NT650 and a GB500, both with cafe style and performance mods. I'm hoping some of you might be able to help with a project - now just in the planning stage - which involves adapting later forks and a disc brake to my '71 Triumph T100 Daytona. I've been advised to just graft on a complete Honda front end, but I'm thinking of something stealthier using a good set of later Triumph forks ('77 T140) that I already have, and my stock triple clamps. The idea is to keep the stock T100 look from above, but with the lighter, more open look of a single disc below. It looks like the later (early 80s) CB750 hub might be a good place to start. The one with threaded holes for the disc on one side - not the earlier ones with the bolts going all the way through. I would have a space of about 5"/126mm between my fork lowers at the axle and would not need the CB speedo drive. The Triumph axle /clamp diameter is 20mm. I don't have, and haven't measured, any of the CB pieces, and wonder if I'm at all close......
Thanks for any input.

 

[Travis]

Hmm.. the CB750 front axles are 15mm. A lot of the older Japanese bikes used 15mm or 17mm front axles. You have to get into the late '80s and early '90s before you start seeing 20mm axles (on the Hondas at least). The CB750 wheel might not be your best bet unless something can be done with different bearings or shims or spacers to make it all work.

 

[calal]

Looking at photos on ebay, I see that CB750 front axles have larger diameter end sections where (I'm guessing) the forks clamp. Am I correct, and are the end sections 15mm or is that the diameter of the middle section where the bearings are? Do all years use the same axle, or does the 80s hub use a different one? I can probably work something out with the bearings, or a custom axle - found parts that are compatible are so much cheaper.
Thanks Again

 

[Travis]

Yeah I wasn't thinking about the larger parts on the ends of the axle.. the axle is 15mm, but I'm pretty sure the end pieces are 20mm. I don't know if they all use the same axle or not, but it looks like it might be a doable swap, especially if you're willing to go with a custom axle if needed. The 5" between your forks might be a limitation. Hopefully someone with a wheel off their bike can take some measurements for you.