Brake Master Cylinder Alternatives?

[dadbike]

I'm rebuilding the brake cylinder and the plunger is frozen solid in the bore. If I can't remove it, are there any upgrades to be found from a different model that would plug and play?

[knoizy]

If you have a look round 454 rider when you click on the blue part number it opens a pdf with all compatible kawasaki parts which makes life easier when searching online as the suppliers often don't know this themselves. 

[lj86454]

I put a master cylinder and lever from an 88 ninja 1000 and it works fine and even has the mirror mount on it so other tha the black lever it looks stock

[yaatri]

I am sorry to raise this issue again. The Ninja master cylinder has a bore of 19 mm while the 454 LTD has a bore of 16 mm. That's roughly 20 percent increase in the diameter and 40% increase in the area. This will decrease your mechanical advantage by about 40%. This means, you will have to  pull the lever 40 percent harder, putting extra torque on the lever. In other words for the same effort, your braking force would be reduced by 40%.  

[eaglerider]

I dissagree....the pressure is going thru the same brakeline to the caliper. The larger plunger moves more fluid, so the pressure would increase to the caliper.It is like opening a water faucett up more....creates more pressure at the end of the garden hose.

[Blaine]

Oct 29, 2018 7:35:54 GMT -6 eaglerider said:

I dissagree....the pressure is going thru the same brakeline to the caliper. The larger plunger moves more fluid, so the pressure would increase to the caliper.It is like opening a water faucett up more....creates more pressure at the end of the garden hose.

I agree Eagle & have done it on several bikes.

[bikeman]

yes that is spot on. one of my bikes has twin front brakes the original MC wasn't big enough to cope with two callipers. a higher capacity one [ZZR600] works perfect it has a 21mm plunger.  the higher the capacity of fluid to the calliper INCREASES the pressure and brake effort not decreases it.


think how old brakes improved with the aid of a servo [pressure increasing device] 

[intillzah]

750 Vulcan master cylinder. Direct bolt on and the stopping performance seems the same...

[yaatri]

I don't mean to argue with you all, accomplished riders and experts in motorcycle maintenance but I submit the following for your consideration. Maybe you can find the fault in my reasoning and I can learn something from it.

As I see it, there are two aspects/jobs of a master cylinder. One is to push enough fluid through the lines and the other, is to provide sufficient pressure at the brake piston.

A larger bore will certainly allow more fluid to be push through, which will reduce the throw length making pads contact with the disc sooner than they would with  smaller bore master cylinder. Once pads have made contact with the rotor, braking power comes from the pressure in the hydraulic system, not from pushing through more fluid faster.  Pressure in the lines is the same everywhere, Pascals's law tells us that, and the pressure in the fluid is determined by the force on the brake lever divided into the area of cross section of the bore of the master cylinder. Larger bore means less pressure for the same force of the lever, which in turn means less braking force at the pads, which can be calculated by multiplying the pressure in the brake fluid by area of cross section of the piston.

Fluid velocity does not play any role in this as we are dealing with static situation.  

[bikeman]

yeah well as the saying goes there's theory and the real world.   I see a couple of flaws in the reasoning.  one is the mechanics of the brakes.  the movement of the pads on to the disc is very small given that if the brakes are working as they should, they only pull away from the disc is due to the deflexion of the piston rubber seals when the pressure is reduced. the piston only slides through the seals when there is no resistance felt [newtons law] being that there is no opposite reaction to counter. when there is the piston "which is grabbing the seal by the edges" twists the seal in order to operate the brake.  if the volume is made greater there is less effort needed to move the piston further so therefore applies the brake sooner and with less travel at the lever end.

second while it is true the internal pressure inside the system is the same everywhere because fluid does not compress it is not constant but in a state of flux dependant on the effort put into the system at the lever end. 

more lever more pressure. or to put it another way soft or hard braking. if you increase the volume of fluid being applied to the system it decreases the amount the lever that has to be pulled for the same braking effect. [more lever more brake].

this leads to the last point if your lever applies the brake at half travel to the bar you have a maximum amount of pressure you can apply for the last half of travel. but if the lever only move 1/4 of the travel to apply the brake you have 50% more pressure in the last 3/4 of travel of the lever.  so the brakes are better with a bigger capacity master cylinder. 

[yaatri]

I beg to differ bikeman. Internal mechanism of brakes, such as that of piston seals in the caliper, are at play but they don't change when you change the master cylinder. As I mentioned before, it's important to distinguish between pressure and force.  When your master cylinder bore is larger, you HAVE to apply a larger force at the lever to produce the same pressure in the fluid as before, assuming that the lever produces the same leverage.  

Your point about "theory" and the real world is to be heeded. Theory must account for all of the significant factors at play. Whilst proper operation of piston seals in the caliper is very very important for proper operation of the brake, all they do is "steal" some of the energy transmitted through the fluid and stored as "spring" energy in the seals.  

[bikeman]

the brakes on a bike or anything else is just like a hydraulic jack in principal. so dwell on this. you want to lift a 2 ton weight. and try to do it with a 1 ton jack there isn't enough pressure in it to lift the weight. so you have get a bigger jack with a bigger mechanism and more fluid to lift the weight. 


the other point about the seals is more to do with the brakes operation. a good brake isn't just about the amount of pressure in the system but how that pressure is utilised.

I have stated on previous occasions I do not have a 454 but a one off en500 style cruiser built around a EX500 as part of the build I used the twin brake system off a GTR1100. the stock MC wasn't up to the job so was swapped out for the higher capacity unit off a ZZR. I can if required stand up the bike on the front wheel [not recommended] so the higher capacity MC does work better.


not that it matters though, interesting as this discussion is the OP has disappeared into the sunset without replying how he got on. 

[yaatri]

it is an interesting discussion indeed. 
You are quite right that hydraulic principle is applicable.  We aren't trying to stop a 1000 lb bike with a brake system designed for a 450 lb bike, which would be akin to lifting a two ton load with one ton jack. 

In principle, one could modify a 1 ton jack, my reducing the bore of he master cylinder, by a factor of square root of 2. That would double the pressure in the fluid which would lift a 2 ton provided seals can stand that pressure.

Returning to the brakes, when you double the master cylinder bore, you reduce the pressure to one quarter of the original value, in which case seals are a non issue as they would now be subjected to lower pressure. In order to stop the same bike, you would have to apply four times as much force at the lever.  

If you want to use larger bore master cylinder, you must use a caliper with proportionally larger piston.  


You certainly need larger braking force, at the caliper piston end,  to stop a heavier vehicle.  You can achieve that by increasing the pressure,   (reducing the master cylinder bore)  or increase the piston diameter at the caliper  or some combination of both. Braking force at the pads would be pressure x piston area, less whatever force is used to "spring" the seals.