Topic: Goon's dual disc brakes...

[goon 1492]

I had the stomach bug last week too, mine was out the other end.  

I hate when this little bug comes to visit.....Makes my four kids have projectile vomiting, I did learn that if you can catch it fast enough you can drink a little vinegar and it raises the acidity in the digestive system and keeps the stomach bug from getting so strong. I didn't catch it fast enough and vinegar coming back up hurts...

[754]

I used Gr 8 bolts when I did mine way back.

On my Morris mag, I think I countersunk my rotors at the bolt holes, and used flush sitting chrome c-sunk allen heads.. clean looking..

I am thinking, clearance for the speedo drive means only one side needs clearance, so .080 longer GL bolts should not be a  concern..no need to cut them..

[goon 1492]

Thanks fishhead I am copying all that to this page for easier tracking.

 I prefer to use the 75-77 GL 1000 discs bolts for dual disc-ing the CB instead of store bought bolts. What I have found is the single disc (CB)and dual disc mounting bolts (GL) have a 8mm shank on the bolt and most store bought bolts (that I have found) usually have a 7mm shank. The hub has a bolt hole of slightly over 8mm for a close fit and when the 7mm shank bolts are fitted they are looser than I like to see.
  Will they break? I dont know, it's doubtful,(providing you bought strong bolts) but I have more comfort with the closer fitting shanks of the GL bolts.
 Look at where the threads meet the shank are and you will see the differences in the shank diameter. Same threads on all the bolts.

Top to bottom

GL 1000
--
Store bought (7mm shank)
--
CB 750

[goon 1492]

I also found a thread that had the speedo drive plate and how its ground, I also found saw one in the thread that Fishead posted a link too, it was iggy's setup and how he did it. this is the pic I found

[goon 1492]

found one that had the machined replacement that MCRider was talking about too...That's a nice part...
Found some drool material too.

[goon 1492]

Ok so how does the tab on the drive plate work if the chrome cover that acts as a retainer for the tabs gone now? what retains the tabs now, is it just friction of all the different parts sandwitched together?....

[goon 1492]

Oohhhh I see I see. Thank you, hey that's your double caliper  slice of heaven setup I posted above isn't it?
I noticed that it states in the directions that the chrome ring was discarded and not used in the double setup, that's what made me wonder what was then used to hold the speedo drive plate stationary on the wheel so it would in turn drive the speedo gear box... Did I explain that right?

[mystic_1]

The ears that you bend down engage two flats that are machined into the hub.

mystic_1

[MCRider]

The ears that you bend down engage two flats that are machined into the hub.

mystic_1

What Mystic said. It will become obvious when you put it all together. The chrome ring was just to dress it up, but the 2nd disc takes its place.

[goon 1492]

Ahhhh I see the light! Sorry I just wasn't remembering those flats, but I do see what you mean now.
I do know that when I talk my wife into getting another 750 and build a wanabe streetfighter out of it I think I will try to score a gl front end and be done with it.
Then take notes because we all know that ol' saying of you'll thank yourself later...

[fishhead]

Oohhhh I see I see. Thank you, hey that's your double caliper slice of heaven setup I posted above isn't it?

 Yeah, That was my set up before I sold it and replaced it with better forks and brakes.
  Like others have posted, You'll see what needs to be done when the time comes and you have your wheel off.

[goon 1492]

well now I know why I didn't under stand at first, my wheel doesn't have those notches. One of the other wheels I have does though you can see my wheel with the notched wheel.....
I figured I can layout the notches on my wheel carefully and cut those notches into them, I say this because the wheel doesn't have the new whitewall tire mounted and therefore is not balanced yet. The notches are so close to center that it shouldn't cause too much of a out of balance problem and if it does it should be corrected when I mount the tire and get it balanced.

Does that sound right? Has anyone had to notch their own wheels? I really don't want to respoke the other hub to my wheel.... We do have a new cnc mill at work now I could probably chuck it up on the machine and to it that way, would be much more clean than my chicken scratch dremel cutting.....

[goon 1492]

while I'm at it and speaking ov spokes look at these...
Would be cool to figure out a pattern for our wheels
I say them on an awesome website called instructables.com

[MCRider]

well now I know why I didn't under stand at first, my wheel doesn't have those notches. One of the other wheels I have does though you can see my wheel with the notched wheel.....
I figured I can layout the notches on my wheel carefully and cut those notches into them, I say this because the wheel doesn't have the new whitewall tire mounted and therefore is not balanced yet. The notches are so close to center that it shouldn't cause too much of a out of balance problem and if it does it should be corrected when I mount the tire and get it balanced.

Does that sound right? Has anyone had to notch their own wheels? I really don't want to respoke the other hub to my wheel.... We do have a new cnc mill at work now I could probably chuck it up on the machine and to it that way, would be much more clean than my chicken scratch dremel cutting.....

Thems gotta be there or you don't have a CB750 hub. What's on the other side? I daresay no one has ever notched their own.

[mkramer1121]

I saw this done somewhere, come off the lower tree with one line to one caliper, then unscrew the bleeder valve and come out of that hole with a line over top of the fender down to the other caliper, which carries the sole bleeder valve. Think I'll try it. Doesn't accomplish much but looked cool. Especially with a smaller front wheel and a fork brace to attach it to.

I'm just thinkin' the bleeder is a smaller hole...just double up the banjo, you get the same effect and you can bleed each side separately to get all the air out...in stead of trying to get it out through just 1 bleeder.

[MCRider]

I saw this done somewhere, come off the lower tree with one line to one caliper, then unscrew the bleeder valve and come out of that hole with a line over top of the fender down to the other caliper, which carries the sole bleeder valve. Think I'll try it. Doesn't accomplish much but looked cool. Especially with a smaller front wheel and a fork brace to attach it to.

I'm just thinkin' the bleeder is a smaller hole...just double up the banjo, you get the same effect and you can bleed each side separately to get all the air out...in stead of trying to get it out through just 1 bleeder.

When you take the bleeder out the remaining hole is the same size as the one where you put the supply hose. At least on the early models.

I had sort of gone off on a tangent, offering options to the otherwise perfectly fine options of the junction block or the double bolt or thinning the banjos and putting them on one bolt.

Doing the over the fender thing reduces the visible lines to one. Its a looks thing.  Bleeding any of these setups is not a problem, just a technique.

[mkramer1121]

I saw this done somewhere, come off the lower tree with one line to one caliper, then unscrew the bleeder valve and come out of that hole with a line over top of the fender down to the other caliper, which carries the sole bleeder valve. Think I'll try it. Doesn't accomplish much but looked cool. Especially with a smaller front wheel and a fork brace to attach it to.

I'm just thinkin' the bleeder is a smaller hole...just double up the banjo, you get the same effect and you can bleed each side separately to get all the air out...in stead of trying to get it out through just 1 bleeder.

When you take the bleeder out the remaining hole is the same size as the one where you put the supply hose. At least on the early models.

I had sort of gone off on a tangent, offering options to the otherwise perfectly fine options of the junction block or the double bolt or thinning the banjos and putting them on one bolt.

Doing the over the fender thing reduces the visible lines to one. Its a looks thing.  Bleeding any of these setups is not a problem, just a technique.

Honestly haven't messed w/ stock CB brakes in awhile, my 750 has GL brakes and was recently working on a GL1200, but both of those definitely used an 8mm bleeder and a 10mm banjo...but I take your word for it.

[MCRider]

I saw this done somewhere, come off the lower tree with one line to one caliper, then unscrew the bleeder valve and come out of that hole with a line over top of the fender down to the other caliper, which carries the sole bleeder valve. Think I'll try it. Doesn't accomplish much but looked cool. Especially with a smaller front wheel and a fork brace to attach it to.

I'm just thinkin' the bleeder is a smaller hole...just double up the banjo, you get the same effect and you can bleed each side separately to get all the air out...in stead of trying to get it out through just 1 bleeder.

When you take the bleeder out the remaining hole is the same size as the one where you put the supply hose. At least on the early models.

I had sort of gone off on a tangent, offering options to the otherwise perfectly fine options of the junction block or the double bolt or thinning the banjos and putting them on one bolt.

Doing the over the fender thing reduces the visible lines to one. Its a looks thing.  Bleeding any of these setups is not a problem, just a technique.

Honestly haven't messed w/ stock CB brakes in awhile, my 750 has GL brakes and was recently working on a GL1200, but both of those definitely used an 8mm bleeder and a 10mm banjo...but I take your word for it.

I was thinking as posting that later models, maybe K3 and up (first GL was 75?) are like you suggest, that's why I added that qualification. I know mine are the same.

But I would be curious to see if the id of the line and the id of the bleeder weren't the same in your case. Doesn't matter, just curious. 

[goon 1492]

well now I know why I didn't under stand at first, my wheel doesn't have those notches. One of the other wheels I have does though you can see my wheel with the notched wheel.....
I figured I can layout the notches on my wheel carefully and cut those notches into them, I say this because the wheel doesn't have the new whitewall tire mounted and therefore is not balanced yet. The notches are so close to center that it shouldn't cause too much of a out of balance problem and if it does it should be corrected when I mount the tire and get it balanced.

Does that sound right? Has anyone had to notch their own wheels? I really don't want to respoke the other hub to my wheel.... We do have a new cnc mill at work now I could probably chuck it up on the machine and to it that way, would be much more clean than my chicken scratch dremel cutting.....

Thems gotta be there or you don't have a CB750 hub. What's on the other side? I daresay no one has ever notched their own.

That's interesting....The wheel came off of the bike but when I got the bike it had a dent in the front fender from the oil cooler, a small dent in the right side of the gas tank and the rear brake lever was snapped off. Made me think the bike was rode out into the ditch at one time and not necessarily laid down. There are just a few scraps on the rider pegs, and the front wheel is in tip top shape(made me wonder if it was replaced after the crash).
So I can't figure out why the one that came off the bike doesn't have those notches unless like a newer version that no longer supports a dual disc setup is what replaced it.
I will have to get some mearurements of both hubs tonight and make sure the one that came off my bike isn't too wide to accept dual disc's. That would suck the other wheel I have needs some TLC to get it up to par.

[MCRider]

well now I know why I didn't under stand at first, my wheel doesn't have those notches. One of the other wheels I have does though you can see my wheel with the notched wheel.....
I figured I can layout the notches on my wheel carefully and cut those notches into them, I say this because the wheel doesn't have the new whitewall tire mounted and therefore is not balanced yet. The notches are so close to center that it shouldn't cause too much of a out of balance problem and if it does it should be corrected when I mount the tire and get it balanced.

Does that sound right? Has anyone had to notch their own wheels? I really don't want to respoke the other hub to my wheel.... We do have a new cnc mill at work now I could probably chuck it up on the machine and to it that way, would be much more clean than my chicken scratch dremel cutting.....

Thems gotta be there or you don't have a CB750 hub. What's on the other side? I daresay no one has ever notched their own.

That's interesting....The wheel came off of the bike but when I got the bike it had a dent in the front fender from the oil cooler, a small dent in the right side of the gas tank and the rear brake lever was snapped off. Made me think the bike was rode out into the ditch at one time and not necessarily laid down. There are just a few scraps on the rider pegs, and the front wheel is in tip top shape(made me wonder if it was replaced after the crash).
So I can't figure out why the one that came off the bike doesn't have those notches unless like a newer version that no longer supports a dual disc setup is what replaced it.
I will have to get some mearurements of both hubs tonight and make sure the one that came off my bike isn't too wide to accept dual disc's. That would suck the other wheel I have needs some TLC to get it up to par.

Well I sure don't know everything, and I haven't checked all of them, but the K1 hub and the K6 hub carry the same part number. So somethings fishy. How did the original wheel drive its speedo?
PS: Oops i see the 1978K carries a different number. Beats me.

[fishhead]

I've seen a few that didnt have the flats on the hub, but I couldnt tell you what they were off of.
  Instead of making the tabs that fit in the flats of the hub, you can make them have ears (like it has originally) to fit between the heads of the disc bolts. A GL 1000 chrome speedo drive plate retainer can be used to cover up the ears. (like pictured below). Check the link to the disc bolts that I posted earlier in the thread and look at the way the GL 1000 Speedo drive is flat (not dished like the CB 750) and has ears. That is what you want to replicate (the GL 1000 speedo and drive plate is completely different with different measurements and wont work).

   I deleted my other post in this thread because the information was wrong. The early sandcast had the tabs that fit into the flats of the hub (as far as I know).
 
 

[goon 1492]

well now I know why I didn't under stand at first, my wheel doesn't have those notches. One of the other wheels I have does though you can see my wheel with the notched wheel.....
I figured I can layout the notches on my wheel carefully and cut those notches into them, I say this because the wheel doesn't have the new whitewall tire mounted and therefore is not balanced yet. The notches are so close to center that it shouldn't cause too much of a out of balance problem and if it does it should be corrected when I mount the tire and get it balanced.

Does that sound right? Has anyone had to notch their own wheels? I really don't want to respoke the other hub to my wheel.... We do have a new cnc mill at work now I could probably chuck it up on the machine and to it that way, would be much more clean than my chicken scratch dremel cutting.....

Thems gotta be there or you don't have a CB750 hub. What's on the other side? I daresay no one has ever notched their own.

That's interesting....The wheel came off of the bike but when I got the bike it had a dent in the front fender from the oil cooler, a small dent in the right side of the gas tank and the rear brake lever was snapped off. Made me think the bike was rode out into the ditch at one time and not necessarily laid down. There are just a few scraps on the rider pegs, and the front wheel is in tip top shape(made me wonder if it was replaced after the crash).
So I can't figure out why the one that came off the bike doesn't have those notches unless like a newer version that no longer supports a dual disc setup is what replaced it.
I will have to get some mearurements of both hubs tonight and make sure the one that came off my bike isn't too wide to accept dual disc's. That would suck the other wheel I have needs some TLC to get it up to par.

Well I sure don't know everything, and I haven't checked all of them, but the K1 hub and the K6 hub carry the same part number. So somethings fishy. How did the original wheel drive its speedo?
PS: Oops i see the 1978K carries a different number. Beats me.

Well my friend you don't know everything, but you do know alot.
Besides if you knew everything the government would have scooped you up and taken you away to keep others from knowing too.
The original wheel came off just like a normal setup with the drive plate being held in place by the chrome ring then the gear box going over that with the axle going thru.....If I remember right.... I do think I will show the dual setup with gearboxes and all next to the norm. setup for comparison when building since I have an extra set.
Fishhead I am going to go back and see what you were talking about first thing in the morning.
Tygrant also thank you for the link to the master cylinder I might just go that route, forgot to mention that a few pages ago....

[754]

If your NOTCHLESS hub does not have fins between the spoke flanges, it is probably a 77/78 K hub..

[Industrial Cafe]

I WAS DIGGING THRU MY LINKS AND FOUND THIS
capslock!!
http://www.anubiscycle.com/cb750-dual-disc-brake-install.htm

[MCRider]

I WAS DIGGING THRU MY LINKS AND FOUND THIS
capslock!!
http://www.anubiscycle.com/cb750-dual-disc-brake-install.htm

This is the same article ben posted on this site http://www.sohc4.net/index.php?title=Dual_disc_conversion

I spoke via PM with Ben the author and he agreed the reference to the CB500/550 speedo drive plate is an error.

Besides that, the piece is a great work and I wish we could make the effort to clean up the speedo drive issue, maybe inject some of the pictures of the drives that others of us have hacked together.