master cylinder advice

[scobysv]

Hi All,

I'm gonna change the stock master cylinder on my race bike (curvy) as the brakes still dont have a sharp feel to them, even after I've fitted newer calippers from a crashed k7, braided lines , race fluid and race pads.

Is there another/better stock Suzi master cylinder that some of you have tried, with better performance?

thanks in advance

Scoby

[DarrenSV650S]

Gixxer ones are larger so more powerful

[petevtwin650]

I had a Gixxer radial one on my Curvy. The brakes were definately stronger and had more feel too.

[scobysv]

thanks for the replys..... I take it they fit straight on (same size clip ons)

cheers

[Stu]

Hi All,

I'm gonna change the stock master cylinder on my race bike (curvy) as the brakes still dont have a sharp feel to them, even after I've fitted newer calippers from a crashed k7, braided lines , race fluid and race pads.

Is there another/better stock Suzi master cylinder that some of you have tried, with better performance?

thanks in advance

Scoby
Surely gixxer calipers are what you want? Adaptor plates are available from dirtydog on here

[scobysv]

Surely gixxer calipers are what you want? Adaptor plates are available from dirtydog on here

We think the mastercylinder is the prob, maybe we will have to go the route youre saying..... I have tought bout it. Gixer calipers aint cheap though.

cheers

[Stu]

Ah, didn't realise you were a racer & probably knew all about them anyway.
Be interested to know how you get on with the MC if it makes a big difference :thumbsup:

[northwind]

Recent R6 and R1 m/c is a very nice part- it's Brembo designed but built in-house by Yamaha. Well made... And it's a 16mm, which is more or less the equivalent of the stock item, though the pivot point is different. It works very well with the stock calipers I feel, though that's very much a matter of taste, it's got slightly more effective power but it just feels better, very direct. It's similiar to a direct upgrade. I still have one on mine, and I feel no urge to upgrade, even though I've used the billet superbike-spec Brembo m/c, you'd think that'd spoil me for anything less but it doesn't.

The GSXR Tokico 18mms, I didn't get on with at all, fair play I was comparing it with that brembo 18mm, and it didn't compare well... Squashy. Flexy. Distant. Generally like a more powerful SV m/c, it was strong but it wasn't good. It's fairly typical of OEM spec m/cs, I think Kawasaki might actually use the exact same part, Triumph use a similiar one. It doesn't really flex much at all but it was enough to be offputting for me.

Your mileage may vary, of course, there's a huge slice of personal taste in this. I like a long lever throw with as linear braking as I can get, I don't like bite and I don't like ramping. But I think for race use, bite is probably good and ramping could be. And not everyone likes the long throw, because of psychology as much as anything else, short travel tends to feel more powerful and very direct and connected. But long travel gives me more control, I think, I just stop better with it.

[yorkie_chris]

Gixxer ones are larger so more powerful

FFS. That isn't how hydraulics work at all.

[DarrenSV650S]

What do you mean?

[yorkie_chris]

Soory if that sounded aggressive or anything.... I should be breathalysed before I can sign into the forum lol.

So many people have this wierd impression that a larger m/c will be more powerful "because it moves more fluid innit" ... No! Fail! An m/c of smaller bore will give the most absolute braking power. Just google hydraulic force multiplier.

In the m/c. Pressure = force1 / area1
In the caliper force2 = Pressure x area2 (this is for force on the pads, so actual BRAKING EFFORT)

So. Force on pads = force on mastercylinder x (area1/area2)

So to get more force on the pads, make the area of piston in the caliper bigger (more pistons, bigger pistons), or make the area of the mastercylinder piston smaller. Or squeeze the lever harder.

The other thing to mess up that nice neat rearrangement is the leverage ratio of the lever on the mastercylinder piston. It varies from model to model.

[DarrenSV650S]

Soory if that sounded aggressive or anything.... I should be breathalysed before I can sign into the forum lol.

So many people have this wierd impression that a larger m/c will be more powerful "because it moves more fluid innit" ... No! Fail! An m/c of smaller bore will give the most absolute braking power. Just google hydraulic force multiplier.

In the m/c. Pressure = force1 / area1
In the caliper force2 = Pressure x area2 (this is for force on the pads, so actual BRAKING EFFORT)

So. Force on pads = force on mastercylinder x (area1/area2)

So to get more force on the pads, make the area of piston in the caliper bigger (more pistons, bigger pistons), or make the area of the mastercylinder piston smaller. Or squeeze the lever harder.

The other thing to mess up that nice neat rearrangement is the leverage ratio of the lever on the mastercylinder piston. It varies from model to model.
Ok so your saying a larger m/c won't make your brakes more powerful. But surely (don't call me Shirley) a larger m/c will give you full braking with less lever movement no? Whereas a smaller m/c will require more lever movement to get to the same braking point

[yorkie_chris]

You are correct. But the larger one will have less pressure.

Once the discs touch the pads that is it, there is no more movement worth thinking about, any movement then is compression of fluid, flex in lever, flex in caliper, expansion of lines and compression of the disc.

Braking power is determined by the clamping force, not a function of movement.


So, a larger m/c will make them bite with less lever travel, but with less actual braking power than a smaller bore.

[DarrenSV650S]

I don't understand how it would have less pressure

[yorkie_chris]

Pressure = force / area

[DarrenSV650S]

But the area of the inside of the lines and callipers are the same. It's only the m/c piston area that's bigger and that is controlled by how much I pull the lever. So surely (don't call me Shirley) if I pull it hard enough I will get the same, if not more pressure

[yorkie_chris]

No, the m/c piston area is constant, given by ((piston diameterx10^-3)xPi) / 4

Why "if not more pressure"?

For the same force on the piston, you will develop more pressure in the system with a smaller piston.

[scobysv]

thanks for the replys and maths lesson....:-D

@ Northwind, what year R6/R1, sounds like the mod I've in mind .. cheers

[northwind]

I think every one with the 4-pot radial calipers gets the same m/c. Mine is off an... 05 R6, probably.

[scobysv]

I think every one with the 4-pot radial calipers gets the same m/c. Mine is off an... 05 R6, probably.

thanks man...... I'll let you guys know how it goes

[flymo]

Strange....I've raced my K3 for a year now using stock master cylinder. I have EBC discs and race pads and I find the front brakes are superb. I certainly dont need any more braking force than I'm getting.

The mod that truly made the most effective change to the braking was valving the front forks along with stronger springs and heavier oil.

[scobysv]

This will be my third season on the SV and I want a better feel and a little more perfoemance. Stock Master cylinder has done its job up to now, but I intend to take in a few rounds of the Irish junior support championship on the roads and that is all about who is good on the brakes, esp when you are up against 400 4 strokes n 250 2 strokes.

[northwind]

I certainly dont need any more braking force than I'm getting.

For me it's all nothing to do with power, this, as you say stock has lots of power, but a good m/c suited to your own preferences makes it easier to put it on the road.