Topic: Rear disc ideas/help

[dusterdude]

Before i abandon my rear disc idea,i thought i would ask ya'll for help/ideas.im having difficulty successfully mounting a master cylinder.does anyone know if there is a way to work both front and rear calipers with the front master cylinder?or is that idea a folly.if anyone has a good way to mount a rear master,please let me know.btw,this is on a k1 750.thanks

[Csrgti]

I've never completed the conversion but I would imagine the easiest way to do it would be to get the parts from a newer bike that came stock with a rear disc brake. As far as using the front maser cylinder for both the front and rear brake that would be incredibly dangerous without an ABS system.
With only the front MC it would control both the front and rear at the same time, there would be no way to regulate brake bias from the front to the rear.

[calj737]

Duster - what you describe would be linked brakes. I've never liked them as the proportional valves are finicky. There are numerous bikes from the mid-80s that used these systems, but by early 90s had given way to ABS enabled systems, which don't prefer linked brakes.

Lots of the modern rear MCs are small enough to mount behind a heelguard on the rear set, but it tends to be the reservoir that needs a creative location. Perhaps the reservoir could be installed on the swing arm pivot flange brace?

[dusterdude]

I was trying to use the stock pedal and pivot,just cant seem to get enough stroke out of it,i keep thinking maybe im missing something.btw,im trying to use a late 90's cbr master mounted horizontally

[70CB750]

I am actually working on it right now. Using 900rr cylinder for F3 rear wheel in K3 frame. Got the cylinder mounted and need to make a new brake pedal - K or F pedal are wrong length.

[strynboen]

i have the same idea ..my rear drum are weared aut.
.but is there a smaller disc breake to fit for a cb550...750 disc are just so BIG....but it have to be a spoken hveel..
i have a plan b...turn a adapter to veld in the hub..so i can fit a aftermarked smaller disc/caliber...but it are a hell of work..

[dusterdude]

70,how did you mount your master and pedal?

[KeithB]

but by early 90s had given way to ABS enabled systems, which don't prefer linked brakes.

Riding a 2006 FJR 1300 with linked brakes and ABS.

Anyway, do not use the master for both front and rear.
Bad mojo for sure!

[70CB750]

70,how did you mount your master and pedal?

Thats the master, pedal is in process. I figured I need the master full and bled first to know how the pedal travels.

[dusterdude]

Cool,as soon as i get the orientation of the pic in my head,ill consider that.thanks

[scottly]

I was trying to use the stock pedal and pivot,just cant seem to get enough stroke out of it,i keep thinking maybe im missing something.btw,im trying to use a late 90's cbr master mounted horizontally

How about posting some pics of the parts you are trying to use, maybe mocked-up?

[dusterdude]

Ill do that in the am

[70CB750]

Cool,as soon as i get the orientation of the pic in my head,ill consider that.thanks

It is all in my build. I will finish the brake pedal today and update my K3F thread. Rather easy solution actually.

[dusterdude]

Cool,can you link it for me please?thanks

[Retro Rocket]

Cool,as soon as i get the orientation of the pic in my head,ill consider that.thanks

It is all in my build. I will finish the brake pedal today and update my K3F thread. Rather easy solution actually.

Part question, part answer, could you use a pedal from an early F bike with the master linkage already attached...?

[dusterdude]

Rr,good question,i havent looked at that yet,thanks for the idea

[dusterdude]

Here is my setup as it is now.

[dusterdude]

The pics arent great but while i was taking them,i came up with the idea of lowering the master cylinder and hooking it up to the lower hole in the pivot hoping i get more stroke out of it.so im gonna try that,let ya'll know when i get it done.keep the ideas coming tho

[70CB750]

Using F MC is shooting yourself in the foot - rebuild kits are not existent.

[dusterdude]

Wow,thanks for the info

[Retro Rocket]

Using F MC is shooting yourself in the foot - rebuild kits are not existent.

Agreed, i wouldn't use the F MC, but i would look into using the pedal, actually I have one in my shop, i'll have a look today...

[dusterdude]

Ill keep the pedal in mind,thanks

[70CB750]

Well here is what I just finished, K pedal and K pivot with 900rr MC and some fabrication.

It works, but it definitely needs return spring.  The MC is not strong enough to bring it all the way up.

Details in my build here:

http://forums.sohc4.net/index.php?topic=115305.250

[wowbagger]

Not sure what your plan is for the brake switch but I've been using these for my switch on a few bikes now. They are much simpler than the stock spring switch and have been really reliable.

https://www.denniskirk.com/goodridge/brake-light-banjo-bolt-boot.p271523.prd/271523.sku

[70CB750]

Not sure what your plan is for the brake switch but I've been using these for my switch on a few bikes now. They are much simpler than the stock spring switch and have been really reliable.

https://www.denniskirk.com/goodridge/brake-light-banjo-bolt-boot.p271523.prd/271523.sku

Right on, thats what I will be using front and back - different brand but essentially the same thing.