Another Brake ?

Badolds81

XS650 Enthusiast
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OK so I'm planing on using my front brake lever to control both my front and back brake. I have a 78 that came with front and back disc brakes not sure what bore my stock MC is...my question is this will my stock MC be OK or will i need to get one off a newer sport bike? if so any idea what one will work the best or just what piston bore size to look for?
I am running stainless braided line,stock rotors,an stock single piston calipers if this matters if I'm forgetting anything let me know.

Ps. i know linking the brakes together is not the best idea but its the way i want!:D
 
OK so I'm planing on using my front brake lever to control both my front and back brake. I have a 78 that came with front and back disc brakes not sure what bore my stock MC is...my question is this will my stock MC be OK or will i need to get one off a newer sport bike? if so any idea what one will work the best or just what piston bore size to look for?
I am running stainless braided line,stock rotors,an stock single piston calipers if this matters if I'm forgetting anything let me know.

Ps. i know linking the brakes together is not the best idea but its the way i want!:D
Why?.....
Inquiring minds want to know?
 
There's no way to respond to this. Anyone that does should consider the liability consequences when this person kill's himself and/or others on the highway. Lawyers will have a field day with this. Emails, messages, etc will be tracked back to their origin.
B81 Linked brakes are the results of years of research and development. Company's invest vast sums funding the research, long before the product is released to the public.
 
Because its a clean look and kinda different.didn't think it would be that bad a proportioning valve to distribute the right pressure to each caliper.
 
Because its a clean look and kinda different.didn't think it would be that bad a proportioning valve to distribute the right pressure to each caliper.

Yes, but what about when you are hitting the curves really hard and want to drag just a little rear brake (I NEVER touch the front brake in the twisties) or if you want to powerslide in some gravel?? I've thought about doing it before, and the small benefit largely outweighs the negatives in my mind...

Being able to control each wheel independently is smart.... There is rarely a time when both tires have the same traction and braking power...
 
Being able to control each wheel independently is smart.... but if i don't like it i can always change it just as of right now this is how i would like to set it up,so any help would be appreciated. just looking for a piston bore size recommendation
 
What about when you are going to t-bone a car and you need to lock up rear to lay down the bike? I have used this procedure once and it did save my life from an old blue-hair that ran a red light. Good luck what ever you decide. Tony C
 
I believe I read somewhere that some Guzi's had one of 2 front disc brakes and rear brake disc operated by the front or rear m/c. I think it was the rear. and the front m/c operated the other front disc. So it's not completely unheard of.
 
Honda has had a linked braking system for almost 10 years. VFR 800, Blackbird 1000XX, Goldwing etc. Im sure it aint as simple as linking both but it works the same way, the back works both front and rear and so does the front.
 
Wings and guzzis use the rear pedel to control one front disc. But like others before me have stated I want no part in this either! Not sure about guzzi but Honda has and now also and those were much heavier bikes they were doing this with
 
sometime ago in a different life I couldn't operate a rear brake pedal with my right foot and wanted , needed additional braking force . The bike was a 78 2F0 fitted with mag wheels and dual front discs using the heritage master cylinder (whatever bore that was ) I simply used a long hydraulic line I found in the scrap heap and added a longer banjo bolt to the "T" that split the front brakes . Do keep in mind that the lever needed additional travel (minor hand filing of lever and perch ) The wheels were on new bearings , The discs had little or no run-out , the seals and pistons were as good as I could get them and I took the time to "green in " and adjust the pad slip angle . (determine at what angle the pad sits in the caliper mounting and sand accordingly to place maximum surface in contact with the rotor) Although spongy in nature there was good enough feed back . Standing the bike on it's nose was possible but sudden panic induced lever grabs were unpredictable . In short it worked well enough to ride .
I don't recommend it though . No way to trail brake . Gentle application seemed to activate the rear caliper first but any more abrupt and the rear was locked and the front was in dander of tucking . My year long experience with this setup says don't do it .

~kop
 
well OK so i guess every one thinks it not a good idea.an it very well might not be but if and when i figure it out ill post back till then
 
Of the bikes I have seen that had linked front and rear brakes, they also had a method of proportioning the front to rear bias during braking, acceleration, etc... I can't remember which Honda I saw it on, but it actually had a mechanical linkage from the swingarm to the brake valve. Pretty sweet setup... The most modern bikes that do have a linked braking system are computer controlled as well, to compensate for load variances....
 
Gordon Scott ran one of his builds linked with a proportioning valve, but he said the valve adjustment was maxed out to get any kind of response, so he ditched it and ran a pure linked set up without the valve......maybe he'll jump on and chime in.....I could be way off base here.

The twin caliper 4-piston brembos used a 16mm master cylinder; based on the research that I beleive xsleo did with master cylinder bore size and the single piston XS caliper, he said brake feel was best with an 11mm MC, 2mm smaller than factory. That being said, and with my own research for MC size for a single 4 piston brembo, I'd probably go with a 13mm with the single piston XS calipers for good feel on a dual linked setup.

Call Yoyodyne and talk to Dave, or if you can get a hold of him, MMM at vintagebrake.
 
thanks Blackbetty Ive already pm`d Gorden Scott about the MC he used and how this set up worked out for him. Ill try the others you mentioned.
 
What about when you are going to t-bone a car and you need to lock up rear to lay down the bike? I have used this procedure once and it did save my life from an old blue-hair that ran a red light. Good luck what ever you decide. Tony C

Layin it down is way old school Wives tale. Your brakes and tires will stop You way quicker than sliding uncontrolled on the pavement. Also, watching, and anticipating that the cage driver IS GOING to run that light. If You lock up the rear, You need to practice Your braking. Your front brake is Your friend. That and....Practice. Anticipate. Practice. :bike: Ask any MSF instructor.:bike:
 
This won't work safely without abs for the back wheel. The reason is that with the same braking force applied to both wheels, the rear brake will lock up and lose traction well before the front, so that in any significant braking situation you will always be dealing with a locked rear, which means your rear tire is suddenly going to want to go to the front of the bike because the front tire is producing more drag by not losing traction.

That's a bad thing.


What about when you are going to t-bone a car and you need to lock up rear to lay down the bike? I have used this procedure once and it did save my life from an old blue-hair that ran a red light. Good luck what ever you decide. Tony C

I'm one of the people who has actually been in this situation, and there was no time to lay the bike down. There was time for me to process the dude's brake lights going out, and see his intent (he was looking away from me, at a driver that had the right of way but wasn't moving)

That's part of this though - I was already watching him because HE was the primary threat in my environment. Identify, assess, respond. Like Kieth Code says, always be looking at the place you'll be in 5 seconds, not where you are now. Where you are now is safe, where you'll be is where the danger could be.

I was doing 40, heading into the intersection. He pulled out and then saw me and braked, directly in my line of travel. There was no way to avoid a collision.

I layed on both brakes as much as I could without losing traction, and then as I got closer, I popped the front brake and leaned forward on the grips to throw the bike towards a stoppie and as I hit the guy's car I lept free of the bike and vaulted over the handgrips.

The bike smashed into the car, flattening the front wheel, bending the forks 45 degrees, and snapping off the triple tree. I flew in an arc over the bars with my hands planted, tucked my head under and landed flat on the hood moving about 30 miles per hour.

I bounced off the hood, flew back up into the air and came down again on my feet and tried my best to roll into the energy - not much you can do at that speed.

I got up after the accident, and I was pretty knocked up. My hands hurt from the shock, my back ached but nothing was broken. My helmet was trashed and I'd taken off a lot of leather from my Vanson pants and jacket. I wore my rivited held gloves down to my palms and I'd burned my skin from the rivets getting hot sliding on the pavement, but I was intact.

As I was walking back to the bike an eyewitness came up to me and said that it was incredible. He said that was some kind of batman stunt shit that I pulled.

All I could say was that I was fully in the moment. I spent every bit of my nickel of attention on every element of the task at hand. I remember everything in slow motion, as if it took minutes instead of seconds to occur.

I will also tell you that I could not possibly have survived that incident without fully knowing exactly what my bike would do at the edge of traction. I couldn't have done it without a front brake, I couldn't have done it with bad tires. I couldn't have done it without wearing a full suit of expensive leathers, a good shoei full helmet and the best racing style deerskin, kevlar and metal rivet gloves I could find.

I also couldn't have done it without a fair amount of luck, but that's what it takes. You get your chance, but you need to be ready for it.

I'll never tell anyone not to take stupid chances, but I damn sure want them to know ahead of time when they suggest something like this what the consequences could be. The inability to act or react in a life or death situation.

* Keith Code - a twist of the wrist

I feel obligated to mention that this dude pulled out from a stop sign and encroached on my right of way. When the cop showed up, the guy pulled the cop aside and was talking and joking with him, while I was limping around waiting for the ambulance to arrive. By the time the cop came over to me, he was convinced I'd committed some sort of crime.

Turns out the other driver was a lawyer, and handed the cop all sorts of bullshit while I was half knocked out, so that the cop had the balls to write me at fault, even though there was nothing justifying it.

Sucks, but at least I walked away.
 
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