FRONT BRAKE Master cy....

[gordon62]

Hi all,
I just wondered, I have single disc up front with single brake Master cylinder , if I fitted a double disc M/CY, with single disc, will this set up be ok.....

reason for question, Z Power have a repro double disc m/cy on e-bay, which would be cheaper than refurbing and resealing the old one...

[pertonpc]

Gordon,
I don't think you will get the right feel/ travel if you use a double mc on a single disc set up.

Plus the extra grunt might cause premature seal failure at the caliper end??

You can get double or single repro mc's off ebay so I would go for the right one for your set up - unless you are planning the double disc conversion in the near future.

Single mcs are normally a bit cheaper as well.

From Mark

[Fred the Zed]

Hi Gordon

Please see the recent thread on improving brake performance. It's a simple case of a bit of maths.

I'd anticipate that the the master cylinder for a double disc set up would have a larger bore than one for a single disc set up because of a need to move more volume of fluid (Alternatively the caliper piston size may vary between single disc set ups and double disc set ups). However, hydraulic dynamics is a little counter-intuitive and what you would find is that a larger bore actually causes lower brake fluid pressure for a given amount of lever travel and will make your brake lever feel very solid and the brakes feel so wooden that it would be hard to predict when a lock up is about to occur. Not good.

If the situation was reversed, and you fitted a master cylinder for a single disc set up to a bike carrying a double disc brake at the front , I would anticipate that you would have a smaller bore master cylinder than the system was designed to have and you would get more lever travel but a lot of 'feel' and substantially more braking power, but theres a danger the lever would come back to the bars if the master cylinder bore is too small.

There are limitations to consider and it all comes down to the ratio between the master cylinder bore surface area and the combined caliper pistons surface area. On a road bike I wouldn't want to decrease this ratio by fitting a larger bore master cylinder in any circumstances (which is what you might be proposing) but I might want to increase this ratio by up to about 10%, to improve braking performance.

Read the link and hope this helps.

http://www.z1ownersclub.co.uk/forum/vie ... hp?t=23456

Fred the Zed.

[Mark Tiller]

single disc MC is 1/2" bore and twin disc is 5/8 bore

[750steve]

Personally i think you'll be fine. I'd be a bit more hesitant if you were going dual disc with single M/C............even thats ok sometimes though, i know a guy who has had his front brakes like this for 5 years

[skibs]

hi,i bought one from z power for my z1.need another for my next project & found this....identical & loads cheaper!
http://www.davidsilverspares.co.uk/CB75 ... rt_123912/

even in the same box(but listed for a h***a)

[dave cullen]

THATS A GOOD TIP!

[skibs]

a classic example of what jimmocks bin saying for ages.
take one of these,write z1 on the box & the price more than doubles

[jimmock]

a classic example of what jimmocks bin saying for ages.
take one of these,write z1 on the box & the price more than doubles

Couldn't have put it better myself.

What does the Z1 MC cost in relation to the Honders MC???

Maybe a poem about the "merits" of H***** CB750 ownership is coming soon?????

Who knows!!!!

[nigel bessant]

Maybe a poem about the "merits" of H***** CB750 ownership is coming soon?????

Who knows!!!![/quote]

[skibs]

luvin the poetry jimmock

m/cyl for zed £83ish posted,for h**** £39 posted.

was well chuffed,got a m/cyl for me h2 without being shafted!

[jimmock]

luvin the poetry jimmock

m/cyl for zed £83ish posted,for h**** £39 posted.

was well chuffed,got a m/cyl for me h2 without being shafted!

I am impressed.

This is the kind of thing we need MORE of!!!!

When I was a truck mechanic we used to buy Z cam brake expanders from Volvo cheaper than ERF. It was ERF's we ran.

Eventually Volvo put a limit on us of TWO at a time!!!

[malmojoe]

Got some of the small Stanley reflectors for under the tank of my H1. NOS ultra rare £100 each - I got a pair of NOS ones for £18 - they are off a H**** cub - just got to make the little ally brackets.