Topic: Dual discs speedo drive is hitting rotor

[Ricky_Racer]

BrandEn, before you go spending a lot of additional money, I have a question: If the early/late hubs are interchangeable, and if the early hub is narrower, is the speedometer drive taller on the early 750's? If so, that should solve your clearance problem. Not being a "Sandcast guy" I don't personally know, but I'm certain some of our brethren might.

Oops. Forgetaboutit! I just checked the parts fiche and the same speedo drive number (44800-300-030) is listed for the K0-K5. Sorry for leading you astray.    RR

[brandEn]

I have no idea. Maybe Dream knows?
The speedo drive I modified was the one that was on the bike. Not sure if it was K0 or not but one thing for sure, it doesn't fit. The thought of unlacing my wheel, finding a new hub, powdercoating my hub, ordering and installing new bearings, and relacing my wheel sounds less than appealing.

[754]

Trade you for the right one...

On my Morris mag, I countersunk the discs, then used 10   5/16 chrome bolts.. Looked tits..

[brandEn]

I think I found a hub already but thanks Frank. If I really decide to get rid of it I will let you know.

[Dream750]

I think Ricky_Racer was on the right track in reply #25 ... a taller speedometer drive “retainer” would be needed to compensate for the height differences.

Example of short and tall style: (retainer, gear box) as Yamiya calls them:

http://www.yamiya750.com/index.php?main_page=index&cPath=144_87&sort=20a

If the taller “tang” style is used, then the rotor backside could be milled for pockets to engage them.

It would be a crying shame to replace the K0 hub after a fresh wheel build, perhaps a modified or custom made speedometer drive “retainer” is a possible solution worth looking into.

[flybox1]

  Both my (thinner) rotors, and my front hub were said to have come off K1's, so this makes sense.  Had no idea hubs were different on later bikes.   
You've put a lot of work into that hub...why not find thinner rotors to match.

[Dream750]

It probably won’t be of much help ... found this Honda service bulletin in the SOHC archives that touches on the narrow/wide 750 hub differences:

http://manuals.sohc4.net/CB750SB/750_26.pdf

[Eydugstr]

brandEn - I have one of rangelov's adapters that I'm not going to be using.  If you'd like can measure it for you and post pictures, see if that might be the solution.   Bought one a couple years ago only to find out that they don't work for '77-'78 hubs.

[brandEn]

It probably won’t be of much help ... found this Honda service bulletin in the SOHC archives that touches on the narrow/wide 750 hub differences:

http://manuals.sohc4.net/CB750SB/750_26.pdf

Thanks!
People like you make this forum invaluable with information like that.