Topic: 1976 550CB duel front disc conversion questions

[jjc]

Yes, I know there are other posts on this subject, but I'm confused.

I have a second disc. It is actually my original which was replaced with a drilled disc.  I can drill my original, so disc situation solved.

My questions revolve around what I don't have, where to get it/them & what has to be done to run the original speedo, which I would like to keep (as well as the tech)

I am new and tried to ask questions directly to a member, but don't seem to be able to.  I'm sorry to have you have to go on again about my questions.

what do I have to do / machine, if anything, to my 2nd disc?
what do I have to do to my right hand drive parts? I would like to keep  the drive on the right for the speedo
don't I just have to buy a 2nd caliper, pads, and mounting arm, reservoir with brake switch.
I will change over to braided lines on both eliminating the left tube and block and run a second line from a duel banjo bolt right from the new reservoir.

I will need a reservoir that can handle 2 disc (move enough fluid) also.

If any machining has to be done to anything, is anyone making the necessary part?

[Shtonecb500]

https://www.dudley.nu/projects/CB550_dual_disc/


and this one
https://www.dotheton.com/index.php?threads/single-disk-to-dual-disk-brake-conversion-for-cb750.1525/

[Shtonecb500]

use the links i provided for reference in the above posts. Your stock MC will work for dual calipers on our bikes, just update your lines like you mentioned. All you really need to make the mods is a hand grinder/cutting wheel, they are pretty easy. Just double up on all the parts with the brake system stock side, you will have to most likely space things out to ensure the caliper pads are square with the rotor, I usually use 1mm washers between the fork lower and the caliper arms to space it outward. you will have alot of back and forth figuring this all out for reasons you will figure out.

Have fun.

[bryanj]

Those articles keep coming and are both WRONG.

You need to look at your front wheel hub and see if the spigot on the speedo side has two flats milled on it or not then come back and i will tell you what you need

[MauiK3]

+1 on stock master cylinder.
you'll have a little more lever movement but it works great, just need good brake lines.
I think the CB750s are the same in which case Yamiya will have the parts you need.

[Don R]

  Scroll down to the double disc with no flats on the hub question. The answers are the same for 550 and 750. The stock M/C works fine, you just have more lever travel to move the pads. I'm working on a double disc myself, some guys use 550 double discs and caliper brackets on 750 because the rotor is slightly smaller and lighter.

[jjc]

OK, it was suggested that the enclosed links are wrong info & photos are needed, so I took 2.  Is this what  you need?

[bryanj]

Unfortunately not, it is whats under the speedo drive plate i need to see which involve removing the bolts and chrome plate, i have explained the differences many times but people still get it wrong so only way is to show me.
Under that plate is part of the hub that sticks out, a spigot, and there are two types

[maxheadflow]

While this is a CB750, the process is pretty much the same. Did my CB550F the same way years ago.  Clamp the speedo drive hub in a lathe and machine the side so that the disc fits over it.   2 5mm flatheads to hold in place..

I cut the rivets on the fender and reverse the bracket and forks.

[Don R]

  Like I said above, scroll down to this thread and see what you are asking about.

   http://forums.sohc4.net/index.php/topic,193363.0.html
 
 The part if you don't want to make it.
   https://www.ebay.com/itm/295742330966?hash=item44db9dd856:g:cIIAAOSw92NhPGg~&amdata=enc%3AAQAIAAAA8DFIUNObcqHseHPk6J4qCF5n7zNhpuUJZ%2BP2hO8xiX6W3s1m2CeVNh%2BYZaXAb6DFQc7h1bdozwgmKV2CxvhW%2FMzIinQxpoqFYSRekYRV7NjeJYcY7hN7vMJMuLipgLiF%2FIaPYB40YJLhnCK%2B1sRZhKdifgVWTUagxcVAfFsHEZ9e%2FvNEYD3FxdZkOXPVFOKTizsh%2FwoW5wNiDZ7yhsHYTWCR9wBtOveVbtKy8PDrCCMKCMydZMeWjPT4YKtZFNRyVO%2FMe2dvJzoqOzgP0zWxzzmZSqE2G%2BRDLlGXJoWlzzMNAAIb0rTOsZKQwerFxOfUpw%3D%3D%7Ctkp%3ABk9SR76E4vvHYg

[jjc]

BryanJ
OK, I have stripped down my wheel as far as you can go.

[bryanj]

That is the later hub that needs the plate in the ebay link posted BUT put the second disc on first so as to centralise it better.

The articles are wrong because, as i have posted many times, you CAN NOT use the 500/550 plate as it is identical to the 750, you can use the CB750K0 plate again shown in a link above IF you have the hub with two flats.
In my humble opinion machining out two slots weakens the carrier too much PLUS you have to open out the centre to allow it to fit over the drive plate and this needs accurate lathe work and ruins the disc/carrier for any other use.

[jjc]

Where were the specs on the longer disc bolts?
I have to buy since there are none local. So directions on where to get them also appreciated.

[38rudge]

You will find that the front disc bolts used on the GL1000 Gold Wing will do the job. Don't know if they are still available new but when I did my twin disc I purchase a good 2nd hand set on e-bay.

You might find the following link, if it works, useful as it outlines how I did mine on my CB750K2: http://www.sohc.co.uk/index.php/topic,21171.0.html

[jjc]

Doesn't anyone know the length needed for two discs?
I know I don't need to maintain metric or the same tpi but to order I need to know a proper length. It would be nice to know the other data also so I can order w/o issue.

[bryanj]

8x110 ht bolts with nylock nuts, head end to speedo drive end

[Shtonecb500]

srry bout posting those links, lol.

[MauiK3]

I checked Yamiya, oddly they don’t have the bolts, they used to. Saw some on eBay

[PeWe]

My CB750 K6 has got that type of hub design on its latest wheel.
I use this one.

[bryanj]

Dont worry about the links, i have the odd bad day where reapeated myself makes me grumpy, and yes i have the sweatshirt from Disney

[jjc]

Ya, I'm waiting for my conversation part order to come through.
Thanks for giving me bolt specs . Then I will have to understand just what is left off when I add the new part

[jjc]

do I understand correctly that the thread of the 550 caliper inlet for the brake line is 1.25?  Whats the dia? I want to order some brake lines from Speigler and they rate by an 'M' I believe.

[bryanj]

Its M10 but cant remember wether its 1.0 or 1.25, fairly certain it is NOT the common car one, Honda cars are the same as the bikes, or at least they are here in uk

[Godffery]

 If you'd like; I can cam provide just about anything you'll need for Twin Disc, or even a complete bolt-on kit made to order.
 https://www.instagram.com/p/CJFoMCEB4pF/?img_index=1

 I can also modify the Calipers to mount Banjo fittings directly. 
 https://www.instagram.com/p/CXKnBWCsOiF/?img_index=2

[jjc]

I thought i posted this but I don't see it so - can anyone verify that the calipers brake line inlet is 10m