Master cylinder check valve

Boxerfan said:

In normal use, the valve allows high flow from the master cylinder to the caliper, and in practical terms offers no restriction as the brakes are applied.

hobot said:

dud dear rude dude hobot hole has nothing to do with any check valve *only* the front brake restrictor hole that is labeled as a valve in parts book. It is completely open plain hole in rubber surround so same restricted flow in as out. Chalk and cheese comparison for misdirected obnoxiousness. Fact of the matter is apparently only me and one Texan knows difference of just restriction removed vs restriction removed *plus* ratio" increased. This hole is so tiny and in center of bore that is does hinder bubbles on brake bleeding but completely different physics why than a check valve, my Cdo's never had.

The 'valve' restriction is in the left more end item here with a hard plastic spreader that may look like a check valve to some but has 3 opens to pass fluid freely so only retained as part of return spring tension stack. Try it ya may like it but new mc sales could sag if word gets out.

Click to expand...

Click to expand...

Hey Hobot,
I'm 50% 'let him believe what he likes' & 50% 'I can't believe this conversation is still going on!!' The check valve is a 2 piece construction, a hard plastic bit with a small hole that is exposed all the time and 3 larger holes that are covered by the flexible rubber bit. Flow from the cylinder lifts the flexible rubber bits off the holes, allowing virtually unrestricted flow. Flow the other way presses the rubber onto the holes, sealing them off and leaving just the small hole for flow back to the master cylinder. This isn't myth or opinion, it's well-documented fact.

Cheers, Jon

Hm Jon I did have to pop the hard nibbin out the way to hot nail hole but the way I remember it the nibbin was not close enough to hole face to affect flow so always only the hole blocking flow in or out. Big hole only useful if one wants to retain an otherwise all factory brake thats not pitted and likes the more one to one relation of lever grip to squeal control which I find matches my fear reaction better than higher ratio. Getting fork oil a bit short of air pocket pump down lock distinctly helps tame my panic noise dives. Planned racer braking needs ain't same as surprise cold use to full stops in public.

Still confused what its benefit is in less powerful ratio Lockheed yet comnoz verifies all the upgrade versions have nothing restricting flow. My handy ole SuVee has a bit of a lever hang up on initial fast application if I'm not paying attention, dives forks but immediately after can release and quick reapply w/o any hesitation to over react. May be the number of crashes and half dozen levers broke off messing with the pivot with nothing to do with the hydraulic part. I usually get 2 drops per lever -if I cut 2" off ends. Always carry both levers for all my cycles.