Topic: dual disc 750

[Roach Carver]

tried to install dual discs on my cb750 today. When I got everything assembled on the wheel I had a helluva time getting it back in the forks. Seems to me that with the added width of the extra rotor it forces the forks outward another 1/4 inch or so. I fixed it by putting only one rotor on it. Am I right or am I doing it wrong - or as my wife says, am I just an idiot.

[ProTeal55]

Sounds like something is wrong somewhere ?
I have a dual-disc on my bike - but I didn't "assemble" it so to speak, so I am really no help.
Get ahold of user CHIPPY550, as he just completed his dual-disc setup, and might be of some help...

[Mark M]

What have you done with the speedo drive mount, it will need to be able to sit against the hub not on top of the
disc. Apparently the earlier ones will fit through the hole in the centre of the disc. On my 750F1 I had to trim the outside cover
away, the inner drive also had to be trimmed leaving  1/2" on either side and cut a corresponding notch on the disc mount so that it was held in place and would then turn with the wheel. You may be able to enlarge the disc mounting hole but I discounted this as
I don't have the machine facitilities to do it and also I suspect the clearance on the bolt holes may be too tight.   

[SteveD CB500F]

There's a FAQ which includes instructions (with pictures)  http://www.sohc4.us/forums/index.php?topic=259.msg47003#msg47003

Good luck - let us see the results!

[Roach Carver]

I previously read that article an it was helpful, but I was unsure if it was for a 750. I am thinking of ditching the speedo drive alltogether. I think I will end up having to shim the axle on the rt side, but my main concern is - does the right side need to be sealed or is it ok for the bearing to be exposed. It looks like a sealed bearing to me so I would think it would be OK.

[chippyfive50]

A GL 1000 (75-77) speedo drive and drive plate will mount to the  axle and solve your problems.
 Daniel

that sounds like the easy way.

I eliminated my speedo anyhoo, I had a friend Mill me a custom spacer @ work.
I DO NOT RECALL THE DIM'S, BUT THE TINY LITTLE BIT OF SPACER THAT
STICKS OUT OF THE FORK SIDE OF THE DRIVE RIDES IN THE FORK CROTCH, I.E. THE SAME DIAMETER AS THE AXLE.
THEREFORE: YOU MUST MIC FROM THE INSIDE BUSHING END TO THE "FACE" OF THE SPEEDO DRIVE, NOT THE BUSHING END.

[HondaMan]

I previously read that article an it was helpful, but I was unsure if it was for a 750. I am thinking of ditching the speedo drive alltogether. I think I will end up having to shim the axle on the rt side, but my main concern is - does the right side need to be sealed or is it ok for the bearing to be exposed. It looks like a sealed bearing to me so I would think it would be OK.

It is a sealed bearing, and should be. Just don't hit it directly with the hi-PSI car wash and it will stay dry inside. It will be exposed unless you fab a speedo drive over it.

[cben750f0]

mate its a bolt on affair, loose the chrome cover on the wheel when you put the second disc on, modify the speedo drice plate, it needs to sit inside the second disc you have put on,thus the reason why you loose the chrome cover, make sure the bolt heads are on the speedo drive side,put the axle in and make sure the drive slots in the speedo drive gearbox, line up with the slots on the speedo drive plate, if not then you will have a 1/4" wider wheel.... also i wrote the duel disc conversion doc that SteveD, mentioned, if you need an extra hand leme know...peace mate

[HondaMan]

mate its a bolt on affair, loose the chrome cover on the wheel when you put the second disc on, modify the speedo drice plate, it needs to sit inside the second disc you have put on,thus the reason why you loose the chrome cover, make sure the bolt heads are on the speedo drive side,put the axle in and make sure the drive slots in the speedo drive gearbox, line up with the slots on the speedo drive plate, if not then you will have a 1/4" wider wheel.... also i wrote the duel disc conversion doc that SteveD, mentioned, if you need an extra hand leme know...peace mate

I don't remember having this 1/4" wider problem when I did mine, either.   

[Roach Carver]

Thanks for the help. I have pulled off the dual disc thing for now, as I kind of want to focus on finishing the bike so I can RIDE. I think i put the nut on the axle on backwards last time and that is what threw me outta whack. I think you guys are right. It will fit. I have lost interest in that part of my project. When I get time to drill both rotors I will get back on it and post some pics. Thanks again.

[cben750f0]

cool, just make sure you post some pics when you do... ...peace