Gen1 Front master cylinder upgrade?

[Billy Balthorpe]

I have a standard front set up at the moment and have found that my master cylinder has got a bit "notchy" with quite a lot of travel before biting. So I am going to replace it.
Is there an upgraded master cylinder I could use from a different bike which would work? Like the kind of thing we do with the R6 shock? I'm thinking a radial master cylinder from a bike which uses the blue spot callipers.

[markie_wales]

Billy

I know I'm probably teaching you to sucks eggs, but the main thing to think about if changing the master cylinder if how much fluid is being pushed through the system down to the caliper. Also (if you get to the giddy heights of Rossi) where the pivot is on the new master cylinder as that could change the amount of pressure you will need to exert and how much fluid it pushes through (but for road bikes I've never had an issue with this 2nd point, they are all pretty similar).

So back to how much fluid is pushed down the brake hose per mm moved by the piston. This is to do with the internal diameter of the piston in the master cylinder.

According to this: http://www.yamahafz1oa.com/fz1specifications.shtml  it's 14mm - which is a fairly common size on modern Jap bikes.

if you can find any master cylinder with the same diameter it should be an OK replacement, with the previous caveat of how much throw per pull it gives.

cheers

Markie

[NorthWestern]

Early R1/R6 master cylinders are the same as Fazers apart from having remote reservoirs IIRC - 14mm.  As far as an "upgrade" they will be the same as the fzs one really and of a similar age so unless you are after the racier look then I am not sure it would be worth it.  I am pretty sure they did go to 16mm on later models (and also radial pull) though which would make a difference in feel.


If yours is notchy and needs a lot of pull to start working they sound like they need looking at.  If the system is bled correctly seals and diaphragm are good and not over extended then there isn't really much to go wrong barring any damage.


I run a 19mm radial one on mine and it is much better than std, less pull and a firmer feel with true one finger braking if you want it.

[PaulSmith]

I would do some more diagnosis on the the problem is before committing to such a radical solution. When was the brake fluid last changed, when were the calipers last overhauled, what condition are the pads and seals in, and do you have braided hoses fitted? The fluid and/or the hoses could explain the travel and the calipers and seals could explain the notchy feel, as could wear on the brake lever. Replacing the master would only have an limited effect if it is not the cause.

When I am not happy with my brakes, I do the following jobs in order until I got the feel I wanted: clean and lube the calipers, check and replace the pads,  replace the brake fluid, replace the brake hoses, replace the caliper seals, replace the master.

If it helps, I replaced my master last year with a second hand unit I found ion the net, but that was because of corrosion in the screws holding the lid on. It didn't change the feel.

[Dustydes]

I had standard front brakes until 2 days ago.
Old rubber lines, aftermarket unknown front pads, fluid of unknown age and still only had to use one finger to brake.
I have just changed to braided lines and of course new fluids.
 
One thing to remember is that if you change only one lever then you might have to buy 2 sets of levers to get both looking the same.
I would make sure the bike I get the brake from has a cable clutch that will work as well, so only one set to buy.

Bore size as said is 14mm. Size is cast onto cylinders 14

[Billy Balthorpe]

First off, thanks for the replies.

Ok, I know about lever ratios, hoses and the hygroscopic properties of brake fluid.

The master cylinder has a definite notch and a long travel before it bites, once it bites one finger braking is very easy.

The hoses are going to be changed for braided items and filled with Dot 4 brake fluid (I'm not going down the silicon fluid route), the callipers are going to be checked and lubed. But this will not get rid of the "notch".

I really just wanted to know if there was a recognised (By the people who have had Fazers for a lot longer than me) replacement/upgrade (radial) using the correct lever ratio which would go straight on.

E.G. "Use a radial master cylinder from a 2009 Yamasuhonki CBFZX 1000, that's what we all do"

NorthWestern, which bike was your Radial Master Cylinder from?

[Falcon 269]

I'm thinking a radial master cylinder from a bike which uses the blue spot callipers.

I have one on my Fazer which came from an R1.  I can't recall the model year but I'm pretty sure it was one of the last blue spot caliper R1s before they went to radial calipers.  Works very well but not dramatically different in lever pressure compared with the OE Fazer MC.

[NorthWestern]

Its a modified Chinese one...


http://foc-u.co.uk/index.php?topic=19284.0


I have seen people using all sorts of different master cylinders with blue spots, GSXR, R6, R1, ZX10 etc and they all seem good really.  Yamaha ones are a good choice as the lever will match your clutch lever - unless your using 'tarts handbag' pazzos or some such then that won't really matter

[sadlonelygit]

16mm radial mc from a 5vy r1. 2 finger braking.

[ye6ybedpom]

Early R1/R6 master cylinders are the same as Fazers apart from having remote reservoirs IIRC - 14mm.  As far as an "upgrade" they will be the same as the fzs one really and of a similar age so unless you are after the racier look then I am not sure it would be worth it.  I am pretty sure they did go to 16mm on later models (and also radial pull) though which would make a difference in feel.


If yours is notchy and needs a lot of pull to start working they sound like they need looking at.  If the system is bled correctly seals and diaphragm are good and not over extended then there isn't really much to go wrong barring any damage.


I run a 19mm radial one on mine and it is much better than std, less pull and a firmer feel with true one finger braking if you want it.

Hello friend, i used to research radial vs axial physics parameters and found that 19r ~=~ 14mm axial but has stronger caliper pressure and more rigid feedback. is it correct? can i just take radial 19 from any modern road bike which goes 250+kph + and it wil be better?

[NorthWestern]

They certainly feel firmer.  Better? That's a bit subjective really, firm with less travel vs soft with more travel - that's essentially what you are getting.

I got a new fazer and have not bothered putting a new master cylinder on, it's not really worth it in my opinion. 

[kebab19]

I had a 2008 onwards R6 radial front M/C fitted, well worth doing. Will have a go at explaining the difference.Outright / ultimate braking power is no different than standard, but it's about how it gets to 100%
When you pull the standard lever setup, stopping power increases in a linear fashion - 10% braking power, 20%, 30% and so on.With the radial pump, as soon as you start pulling the lever, it seems to start at 30% then jump to 50% and so on. It moves to 100% quicker / over a lesser distance and with less braking effort.
 

[unfazed]

Most likely cause of the issue is some corrosion/dryness/wear where the break lever and piston rod on the master cylinder meet.
Remove the lever and clean the end of the lever and the end of the piston rod. (I use a plastic kitchen scrubber)
Apply red rubber grease to the ends and put it back together, that should sort it.Replace the brake hoses as they have softened with age causing the increased travel you mention

[Billy Balthorpe]

Sorry about this people. I figured out it was the fancy levers i fitted a while back. I bought some different ones and the notch went away.