« previous next »
Pages: [1]   Go Down

Author Topic: Dual Disks - Line Question  (Read 2916 times)

0 Members and 1 Guest are viewing this topic.

Offline Blitzburgh207

  • Hot Shot
  • ***
  • Posts: 426
Dual Disks - Line Question
« on: February 03, 2012, 10:49:18 AM »
I'm starting to buy parts for the dual disk conversion on my 750.  ...Actually I already have everything besides the lines and the 6 110mm bolts.

I'm wondering if, instead of running two lines from the master cylinder, can I run a single line to the left rotor and have my double banjo there, and then run the second line around the back of the fender to the right caliper.  - Similar to many modern sport bikes.  Any reason that wouldn't work? Uneven distribution?  Anyone done or seen this?

P.s. I've swapped the triples so I don't have that connection on the lower triple anymore.

Thanks!
Logged
1978 CB750 K8

Offline MCRider

  • Such is the life of a
  • Really Old Timer ...
  • *******
  • Posts: 14,376
  • Today's Lesson: One good turn deserves another.
Re: Dual Disks - Line Question
« Reply #1 on: February 03, 2012, 11:01:26 AM »
Quote from: Blitzburgh207 on February 03, 2012, 10:49:18 AM
I'm starting to buy parts for the dual disk conversion on my 750.  ...Actually I already have everything besides the lines and the 6 110mm bolts.

I'm wondering if, instead of running two lines from the master cylinder, can I run a single line to the left rotor and have my double banjo there, and then run the second line around the back of the fender to the right caliper.  - Similar to many modern sport bikes.  Any reason that wouldn't work? Uneven distribution?  Anyone done or seen this?

P.s. I've swapped the triples so I don't have that connection on the lower triple anymore.

Thanks!
I've done it on mine. In fact you won't need the double banjo. Say, one line enters the left caliper. Then remove the bleeder valve and its seat. Then run a line out of the left, over the top of the fender (my calipers are on the back side of the legs) into the right caliper, which retains its bleeder.  I'll get a picture(s).

Since you don't have the joint at the triple, just run one line straight down to the caliper from the master.
Logged
Ride Safe:
Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline MCRider

  • Such is the life of a
  • Really Old Timer ...
  • *******
  • Posts: 14,376
  • Today's Lesson: One good turn deserves another.
Re: Dual Disks - Line Question
« Reply #2 on: February 03, 2012, 11:13:23 AM »




Ultimately I had to unbolt the rt caliper and hold it up to clear the crossover line of air.
Logged
Ride Safe:
Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline Danno

  • Hot Shot
  • ***
  • Posts: 715
  • 74 CB550,75 GL1000,76 KZ400,77 GL1000,73 CB750
Re: Dual Disks - Line Question
« Reply #3 on: February 04, 2012, 02:11:43 AM »
what is wrong with puting the double line at the banjo fitting for the brake light switch just use a longer banjo bolt and a copper washer between the two banjo fittings as pointed out it is a lot harder to bleed the lines without a bleeder and the gravity bleed trick will not work with a crossover line that goes up and over the fender because it acts like a trap for air bubbles
Logged
when you own a motorcycle the wife does not have to find you handy she just has to find you

Offline MCRider

  • Such is the life of a
  • Really Old Timer ...
  • *******
  • Posts: 14,376
  • Today's Lesson: One good turn deserves another.
Re: Dual Disks - Line Question
« Reply #4 on: February 04, 2012, 05:25:05 AM »
Nothing wrong with it. Not as clean in my mind.

Once the line's cleared its no problem. More like a modern sport bike. to each their own kind of thing.
Logged
Ride Safe:
Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline Terry in Australia

  • Really Old Timer ...
  • *******
  • Posts: 33,363
  • So, what do ya wanna talk about today?
Re: Dual Disks - Line Question
« Reply #5 on: February 04, 2012, 05:34:23 AM »
I've got a single line down to the brake light switch junction, then a double banjo bolt with two lines out and it works fine, but Ron's is a good setup, and the PO has stated that he doesn't have the brake light switch junction any more, so he either goes with Ron's setup, or he'll have to run two lines from the MC. Cheers, Terry. ;D
Logged
I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline andrewk

  • doin' it.
  • Hot Shot
  • ***
  • Posts: 626
Re: Dual Disks - Line Question
« Reply #6 on: February 04, 2012, 05:46:56 AM »
What sort of master cylinder are you all using?  Stock?  Anyone know what the stock lever feels like with another caliper in the circuit?
Logged

Offline MCRider

  • Such is the life of a
  • Really Old Timer ...
  • *******
  • Posts: 14,376
  • Today's Lesson: One good turn deserves another.
Re: Dual Disks - Line Question
« Reply #7 on: February 04, 2012, 07:08:35 AM »
Quote from: andrewk on February 04, 2012, 05:46:56 AM
What sort of master cylinder are you all using?  Stock?  Anyone know what the stock lever feels like with another caliper in the circuit?
I've used a few different ones, from salvage yards. I just asked for one from a dual disc bike. Rumore was it was from a Kaw of some sort. Currently fitted a VF500R MC, nice feel but not on the road yet. Come to find out the MC from the VF500 Magna would have a better angle built in for the handlebars. I'll probably change it later. I think using a stock one feels OK, but has an unacceptable length of motion to get full braking.

I like the lower profile and the line comes out the front so it doesn't foul the tach, which happens with clubman bars, not so much the Euro bar i have. But the line is also out of line of site.


Here's my first iteration routing, stacked and looped out front.


Then turned to the back:


Current iteration is just a copy of a modern sportbike routing. I did it because i thought it looked cool. Only one line from above. The crossover line is virtualy unseen.
Logged
Ride Safe:
Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline crazypj

  • I'm brill, me
  • Old Timer
  • ******
  • Posts: 4,467
  • first 100,000 miles. 1977 CB550F
Re: Dual Disks - Line Question
« Reply #8 on: February 04, 2012, 07:38:39 AM »
I used a double banjo from left caliper.
Just remove calipers and put something between pads when your bleeding brakes, it is quite difficult to get all the air out of the cross-over
This is after several years and multiple pad changes on my XS650
Logged
I fake being smart pretty good
'you can take my word for it or argue until you find out I'm right'

Offline Blitzburgh207

  • Hot Shot
  • ***
  • Posts: 426
Re: Dual Disks - Line Question
« Reply #9 on: February 04, 2012, 09:29:08 AM »
Wow thanks for the feedback guys!  Yes, I was originally planning on running one line to the brake light switch and splitting it from there but I'm using shaved triples from a 94 so I don't have that option.  I bought a master cylinder from a cbr600 f3 a few days ago.  I think it should be enough for the swap because they have dual disks up front and also it has a built in brake light switch so it's easy.

MC that's quite the setup you have there - I like it a lot.  I never thought of removing the bleeder and adding a banjo in it's place that's a great idea.  How is that brake setup working for you?  I was thinking about doing that as well but I think I'm going to leave them out front, unless there's some real gains from it.
Logged
1978 CB750 K8

Offline MCRider

  • Such is the life of a
  • Really Old Timer ...
  • *******
  • Posts: 14,376
  • Today's Lesson: One good turn deserves another.
Re: Dual Disks - Line Question
« Reply #10 on: February 04, 2012, 10:17:02 AM »
Quote from: Blitzburgh207 on February 04, 2012, 09:29:08 AM
Wow thanks for the feedback guys!  Yes, I was originally planning on running one line to the brake light switch and splitting it from there but I'm using shaved triples from a 94 so I don't have that option.  I bought a master cylinder from a cbr600 f3 a few days ago.  I think it should be enough for the swap because they have dual disks up front and also it has a built in brake light switch so it's easy.

MC that's quite the setup you have there - I like it a lot.  I never thought of removing the bleeder and adding a banjo in it's place that's a great idea.  How is that brake setup working for you?  I was thinking about doing that as well but I think I'm going to leave them out front, unless there's some real gains from it.
The bike is not finished yet. But its the exact same set up I had on the bike when I parked it in 1995, except for the different MC, the chrome, and smaller diameter braided lines. I had the over the fender line in the last iteration before I parked it. 

But I'm sure it will be just fine as it was decades ago. That's the same bike in all the pictures.

Putting them on the rear, there may be some marginal handling gains if you're going left/right/left a lot. But for a street bike, its just for looks.
Logged
Ride Safe:
Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline Blitzburgh207

  • Hot Shot
  • ***
  • Posts: 426
Re: Dual Disks - Line Question
« Reply #11 on: February 10, 2012, 06:17:30 AM »
Just realized re-reading this thread  ::) that I have the later calipers.



Can I still do this by removing the bleeder screw on one side?
Logged
1978 CB750 K8

Offline scottly

  • Global Moderator
  • Really Old Timer ...
  • *****
  • Posts: 16,396
  • Humboldt, AZ
Re: Dual Disks - Line Question
« Reply #12 on: February 10, 2012, 07:32:55 AM »
No, the early style calipers have the same size hole for the bleeder and the line, while the late style have a smaller bleeder. You might be able to use a double banjo bolt? Also, it looks like the bottom caliper in the pic is for a 550. It won't clear a 750 disc, which is bigger in diameter than a 550.
Logged
Don't fix it if it ain't broke!
Helmets save brains. Always wear one and ride like everyone is trying to kill you....

Offline crazypj

  • I'm brill, me
  • Old Timer
  • ******
  • Posts: 4,467
  • first 100,000 miles. 1977 CB550F
Re: Dual Disks - Line Question
« Reply #13 on: February 10, 2012, 08:13:52 AM »
Quote from: scottly on February 10, 2012, 07:32:55 AM
No, the early style calipers have the same size hole for the bleeder and the line, while the late style have a smaller bleeder. You might be able to use a double banjo bolt? Also, it looks like the bottom caliper in the pic is for a 550. It won't clear a 750 disc, which is bigger in diameter than a 550.

Blitzburg, thanks for the pic, I never looked at 750 caliper arm side by side with 550 one, the angle on bottom' is obvious
I think I may try making a couple of arms so I can fit 750 discs to my 550, looks relatively simple.
Logged
I fake being smart pretty good
'you can take my word for it or argue until you find out I'm right'

Offline Blitzburgh207

  • Hot Shot
  • ***
  • Posts: 426
Re: Dual Disks - Line Question
« Reply #14 on: February 10, 2012, 09:44:32 AM »
those arent my calipers just a picture i found. Thats what i expected though... I have one earlier caliper too maybe ill put that one on the left and a later one on the right?  that would bother me though... Screw it ill buy another finned one. Anyone have one for sale? i have a new piston Im the mail already.
Logged
1978 CB750 K8

Offline cben750f0

  • nothin draws attention like a classic bike!!
  • Master
  • *****
  • Posts: 1,612
  • '75 CB750F0 Gladstone NQLD OZ
Re: Dual Disks - Line Question
« Reply #15 on: February 10, 2012, 01:11:48 PM »
so why not just run a double banjo fitting at the pressure switch? if you have the two later model calipers? i think i might have missed something here?

Goodluck with it

peace
Logged
you are never to old, to act like a kid... be safe
funny thing,chasing someone down hill on a bike 30 years older than theirs..
he said \\\\\\\'it was like watching a 250kg unguided weapon getting stuck up you bum\\\\\\\ http://www.bikepics.com/members/trixtrem/

Offline Blitzburgh207

  • Hot Shot
  • ***
  • Posts: 426
Re: Dual Disks - Line Question
« Reply #16 on: February 10, 2012, 03:28:55 PM »
No it was me that missed something... I shaved the handlebar clamps off a set  of 74 triples and i thought that there wasnt a switch on them. But i finished them up today and there is a switch. Problem solved i guess haha
Logged
1978 CB750 K8

Offline cben750f0

  • nothin draws attention like a classic bike!!
  • Master
  • *****
  • Posts: 1,612
  • '75 CB750F0 Gladstone NQLD OZ
Re: Dual Disks - Line Question
« Reply #17 on: February 10, 2012, 05:58:42 PM »
lol it would have been on the lower tripleclamp... glad you got it sorted  8)

there should be a write up i did in the FAQ or a sticky in the brakes section of the forum...(i think)

good luck with it.

peace
Logged
you are never to old, to act like a kid... be safe
funny thing,chasing someone down hill on a bike 30 years older than theirs..
he said \\\\\\\'it was like watching a 250kg unguided weapon getting stuck up you bum\\\\\\\ http://www.bikepics.com/members/trixtrem/
Pages: [1]   Go Up
« previous next »