Brake master cylinders

[morinisteve]

For R13's Cb750 project, we've been talking about using the front brake lever from Goose's CB900. We'll have to figure out what the diameters are, but here's the chart for pistons in the caliper to master ratio's. Also a good description of why it matters
http://www.vintagebrake.com/mastercylinder.htm

[Goose]

I completely agreed but feel the rotor size is way less important then the master cylinder to caliper piston sizing which is where the ratio comes from (right). Basically you could make a smaller rotor stop better and have better feel by using a better master cylinder to caliper piston ratio.

[Seth]

Agreed. the diameter of the Rotor should not matter.. its all how the caliper grabs the disk... Do we know if the CB900's will fit the 750? I cant read charts its all french to me....

[2StrokeLover]

They all will bolt together and work...It is a matter of you want it to feel like..Wood or over sensitive where it locks up way too quick..With that said I've mixed and matched M/C's and never really had a bad result...But most of the shit I work on is old and don't stop good anyhow..

[fletch]

Do you think you would get more braking effect with a bigger rotor,getting more leverage from being away
from the center.The bigger rotor will disapate the heat better,not a big deal on the street.I'm going to go look at a Rickman Triumph project this weekend,may try and stop at your sunday night workshop if its oK.

[morinisteve]

I think the Diameter in the chart is the diameter of the actual piston(s) in the caliper itself, which would effect how much fluid needs to be pushed against the surface area of the piston(s)in order to squeeze the brake pads against the rotor.
But anyhow I think this will do the trick. Both the bikes have a 5/8 piston in the master cylinder! See page 2:
http://www.rg500delta.com/RG500_chassis ... 0sizes.pdf

[R13]

I forget, why did we need to switch them out in the first place?

[Seth]

So that you can get your braided single line from the master cylinder to the caliper... and bypass all that metal honda tubing crap.. But hey its your bike

[2StrokeLover]

You did that just for the front brake switch on the newer master?...My gixxer came stock with only a rear brake light switch...I found that pretty odd...I might have a old honda master around also..I'll look today..I know i had one with a broken lever but other wise it was nice with the switch..

Oh and Steve thank you so much for that chart...That will come in very handy on fine tuning franken brakes...Feels
like wood go to a bigger piston M/C...No need to figure anything with 3 basic sizes..

[morinisteve]

No prob Walt, I'm still figuring all this stuff out, so I have to look a lot of shit up. Only takes a few sec to put what I find on here. course that includes all the stuff you've known for years.
We're changing the lever so it will have the Brake light switch in the lever instead of a BS sensor in the middle of the brake line. since Mark has a CB900 for parts, we'll steal it off that.