Swapping Master Cylinder on 74 CB360

Been contemplating swapping out the stock MC on the 360 for a while now. The clearance on the stock M/C to the clipon mounting hardware is not enough to allow me the proper angle on the lever for comfortable operation. I've done a bit of research, and I know the caliper piston is 38mm, and the stock MC piston is 14mm.

As of right now, the front brake lever 'feel' is not great, there is short travel and progressive braking is not ideal. According to the MC ratiio chart that I see linked all over the place (http://www.vintagebrake.com/mastercylinder.htm) the factory ratio for the CB360 is at 7.37:1, and their 'sweet spot' is somewhere between 14:1-12:1 range. I take that chart with a grain of salt, as every brake set up is different. But I do believe a slightly higher ratio would result in a better feel at the lever. I have read about a few people switching to a MC with a 12.7mm piston, which would put the ratio somewhere between 9:1-10:1.

Here's one of the master cylinders I found with 12.7mm piston: http://www.ebay.com/itm/291462071546?ssPageName=STRK%3AMEBIDX%3AIT&fromMakeTrack=true

If there are other options that are compatible from modern sport bikes I'd consider that possibility, but I don't love the look of the floating plastic reservoir on a vintage bike. I've already bought new stainless brake lines, so I'd like to keep those compatible as well.

Haha - "Assembled in California" :


At that price, it's worth a shot anyway

Right? Made in China, Assembled in USA so stick a big flag on the picture ;D

Got the master cylinder in during the week, and had time to get it fit and bled over the weekend. Definitely improves the lever position and has a pretty decent lever feel. Haven't had it out on the road.

My concern is that because of the configuration of the reservoir and the angle/position of the assembly and handlebars, could there potentially be a risk of exposing the inlet valve in the master cylinder to air during riding, therefore rendering the brakes unusable?

Considering that the inlet valve is in the middle of reservoir and its full of fluid, I would think that this wouldn't happen. Any thoughts?

I have done many, many mc swaps on bikes with clip on bars - some with very suspect angles with regard to the reservoir. Many that required either leaning the bike over nearly on the ground with the bars turned just to be able to put fluid in even needing to remove the master to fill it and bleed the system. Never had an issue and some of these bikes were ones that I had personally for a long time. As long as the reservoir is filled and the diaphragm is installed and in good shape you should never have an issue - at least that is my experience.

I've used this M/C from David Silver a few times with clip-ons, they work very well

jpmobius said:

I have done many, many mc swaps on bikes with clip on bars - some with very suspect angles with regard to the reservoir. Many that required either leaning the bike over nearly on the ground with the bars turned just to be able to put fluid in even needing to remove the master to fill it and bleed the system. Never had an issue and some of these bikes were ones that I had personally for a long time. As long as the reservoir is filled and the diaphragm is installed and in good shape you should never have an issue - at least that is my experience.

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Good to know. The angle made me a bit nervous but you'd basically have to have the bike sideways for the fluid to clear the inlet. I'll just keep the fluid topped off and be on my way.

I like to run an external reservoir. Makes the issues you are having, no issue at all.