Smaller Master Cylinder LEVER options

Brassneck

Brassneck

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Hey All,

I posted this within a different Master Cylinder thread a few weeks back--trying to keep topics in line, but I didn't get any bites...so figured I'd start a new one instead with hopes of getting some info from anyone that may have intel.

I'm looking to get a smaller bored piston MC vs. my stock 14mm MC...This is more for my own interest to improve performance versus the actual need to do so as my brakes work just fine and I don't really have any concerns, especially from a 37 yr old bike. (In case you are wondering: I've cleaned/rebuilt the MC and Caliper about a year + ago; flushed/new fluid, SS Brake Line, Vesrah pads from MMM, XS performance rotor and all functions very well.) Really no complaints except that it's more like a two or 3 finger pull vs. a 1 or two finger pull to get solid brakes and I think a smaller bore will make them even better.

I have found a few smaller bore MC options, but here's the delima: I'd like to keep the lever I have got for my stock MC as it matches the Clutch side. (I know, I know...anal. LOL. I really like to keep things balanced, and for me levers just have to be the same left/right).

Does anyone know if Mike's MC (# Part #08-0255), will allow the use of use my current stock lever? Or if there's an even smaller piston bore (11mm?) that will fit my stock lever? Alternatively, if there's a set (Clutch/MC) that would work too...oh, and not black levers. Ha ha.


Any thoughts? (Other than I'm nuts... I already know that).

Thanks!
 
Thanks Angus! Yep that was the one from Mike's that I was looking at...so I'm assuming the stock levers will interchange on it?
 
I dont know if they interchange because of a different brake lite switch. Didn't really check, since the lever matched my stock clutch lever
 
Reducing the master cylinder bore will certainly result in an easier pull but like many things in life you get owt for nowt

The lever will need to move further to displace the same amount of fluid as the OE m/c and the feel will be softer. Can't say by how much and only you will be able to decide if it is to your taste.

Have a read of this which explains further
 
Right, Max; that article was written by Michael Morse, who also owns 650 Central and who recommends using an 11 mm. MC with the 77-forward OE caliper on the XS650. And I can assure you from experience, not speculation, that there is no downside to using the 11 mm. MC with the OE single piston caliper, assuming that a braided stainless line and quality pads are also installed. (I once asked Michael why manufacturers back in the day tended to use oversized MC's; his guess was that it was to keep rookie riders from locking up the front wheel.)

Brassneck, I have no idea which levers look like which, but you might also look at 1/2" MC's.
 
Max Midnight said:
Reducing the master cylinder bore will certainly result in an easier pull but like many things in life you get owt for nowt

The lever will need to move further to displace the same amount of fluid as the OE m/c and the feel will be softer. Can't say by how much and only you will be able to decide if it is to your taste.

Have a read of this which explains further
Click to expand...

Thanks Max, yep...totally get it and thanks for the link.
 
grizld1 said:
And I can assure you from experience, not speculation, that there is no downside to using the 11 mm. MC with the OE single piston caliper, assuming that a braided stainless line and quality pads are also installed.
Click to expand...

Whist I can't comment on the feel of an 11mm dia. m/c it is reasonable to point out that Mr B will notice a difference from his current arrangement.

As I said in my previous post you don't get something for nothing and the lever will have to travel further to give the same degree of retardation plus it will have softer, more spongey feel. Only Mr B can decide if it is to his taste.
Some of the softer feel can be reduced if stainless hoses are fitted especially if his haven't been replaced for many years.

And I can assure you (having ISR adjustable lever ratio m/c's on my V Max) that altering the ratio does make a considerable difference to the feel of the brake.
Too low a ratio and the lever is wooden with very little travel and feel; too high you get spongy feel with long travel (at the extreme end of the continuum it is possible to pull the lever back to the bar).

As it suggests in the article there is a sweet spot but within reason personal preference will dictate where this is.
 
Longer travel, Max? Sure, leverage is altered, that's the point. Spongy feel? Hardly. With stainless lines and proper pads the feel is firm and more controllable than OE, as well as more powerful. You'd do well to maintain a match between your comments and your experience and to pay attention to the recommendation of the guy who produced the Vintage Brake chart you linked to.
 
And with respect you would do well to pay attention to the physics involved.

As you have read the article you will have noted that it says 'Ratios lower than 20:1 can result a feel so "wooden as to have a toggle switch effect"'. This is due to the m/c piston not having to travel very far do displace sufficient fluid to move the calliper pistons. It also states that 'I like ratios in the 27:1 range-2 finger power brakes, feeling some line and/or caliper flex'.
The feel comes back into the lever as the m/c piston has to move further to displace sufficient fluid to move the calliper pistons.
There is no comment about ratios higher than 27:1.
The further the ratio moves beyond the 'sweet spot' the lever has to travel further to displace the fluid.
As a low lever ratio gives a wooden feel then it is not unreasonable to extrapolate that a high lever ratio will give a softer (or spongy) feel which has been my experience.

The following is an extract from Merlin Motorsports web site. For pedal substitute lever.

IF YOU INCREASE MASTER CYLINDER BORE DIAMETER:

Increase Pedal Effort
Decreases Total Pedal Travel
Reduced Push-rod Stroke to Master Cylinder Decreases Line Pressure for a Given Pedal Force

IF YOU DECREASE MASTER CYLINDER BORE DIAMETER:

Decrease Pedal Effort
Increases Total Pedal Travel
Increases Push-rod Stroke to Master Cylinder Increases Line Pressure for a Given Pedal Force

I stand by my point that changing the diameter of the m/c piston will alter the feeling of the lever a fact which is made in the Vintage Brake and Merlin Motorsports web sites.

I also reiterate the point that I can't comment on the feel of using a m/c with an 11mm diameter piston.
 
Quick update...I ended up getting the 13mm bore MC from Mikes...pretty much a direct swap, and the feel is GREAT!

The gamble was would it work with my old levers, and the answer is YES. All is well.
 

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