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Author Topic: Proposal and RFC left hand rear brake  (Read 1116 times)

clay.leihy

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Proposal and RFC left hand rear brake
« on: June 28, 2017, 10:54:09 PM »

I was considering the following:

Get left hand brake cylinder/lever.
Locate line from rear master cylinder to ABS and disconnect from cylinder.
Reroute line to front and connect to left hand master cylinder.
Fill, bleed, good?

Anyone know why this would not work? Any suggestions or recommendations? Anyone already done this?

Sent from my Z981 using Tapatalk

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Clay
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adaviel

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Re: Proposal and RFC left hand rear brake
« Reply #1 on: December 03, 2017, 02:06:50 PM »

I was considering the following:

Get left hand brake cylinder/lever.
Locate line from rear master cylinder to ABS and disconnect from cylinder.
Reroute line to front and connect to left hand master cylinder.
Fill, bleed, good?

Anyone know why this would not work? Any suggestions or recommendations? Anyone already done this?


I did that recently. I got a left-hand brake lever with master cylinder from a local bike shop (not sure what's it's off - he said "does it matter?"). The rear brake line is just about the right length. I was able to bleed out the line through the master cylinder - I took the lid off and pumped carefully, keeping the cylinder filled with fluid and watching bubbles till they stopped and I was able to feel the brake work. My aim was to have an effective left-hand control to use while backing my bike down a narrow ramp - without a clutch and the resistance of a piston engine, the front brake alone cannot hold the bike. That works fine.

What did not work was my attempt to have both the hand and foot controls work. I should have figured this out before spending $100 on a hose and a few hours of my time, but 3 motorcycle technicians at 2 different bike shops failed to point out it was stupid when I explained what I wanted to do. If you do that - fit a double banjo bolt on the ABS controller and connect both master cylinders - what happens is that one reservoir pumps into the other one because the reservoir port is open when the lever is not depressed. I guess you would need to fit a separate caliper and brake line. You can have two slave cylinders (two front brakes) on a double banjo because slave cylinders have no vent.



I had previously ordered a cheap clutch kit online, as suggested by a different bike tech, but that turned out to have the wrong size fittings, and was probably too small - a small cylinder volume and reservoir - although the reservoir was on the correct side of the lever. Someone else told me that snowmobiles often have a left-hand brake, which may be another option.
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Keith

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Re: Proposal and RFC left hand rear brake
« Reply #2 on: December 03, 2017, 06:23:25 PM »

Yes as far as I can tell there are only two ways to get left hand brake and pedal together. I did it by linking them mechanically with a cable that pulls the pedal from a handlebar lever. http://electricmotorcycleforum.com/boards/index.php?topic=5328.msg50287#msg50287  Clake had an expensive hydraulic alternative that used the pedal cylinder to drive a slave cylinder that drives the handlebar master cylinder that drives the rear brake. A nightmare to bleed, complex and difficult to install but possible. And it looks like they no longer sell it. http://www.clake.com.au/which-clake/ I can't unlearn the use of a pedal, it's instinctive after decades of dirt riding. I mostly use front lever brake light triggered regen rear wheel braking to slow down. I use the left hand lever to slow down more and to get control while riding with feet off the pegs or rolling backwards. But to really lock the rear while sliding off road downhill or around a switchback, the pedal works best, so I won't give it up even though a hydraulic left hand would perform better than a cable.

Maybe someday the electrics will have really good variable regen linked with hydraulic braking. But that will take a lot of R&D so it is years away. And the mental transition to handlebar controls instead of pedal will slow down adoption.
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clay.leihy

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Re: Proposal and RFC left hand rear brake
« Reply #3 on: December 04, 2017, 08:01:08 PM »

Yes as far as I can tell there are only two ways to get left hand brake and pedal together. ...
To have functional rear brakes lever and pedal you need this: (https://www.tacticalmindz.com/collections/gp-tech-handbrake-kits) The new handlebar mounted master cylinder/reservoir replaces the stock rear reservoir.

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« Last Edit: December 04, 2017, 08:20:11 PM by clay.leihy »
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Clay
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Keith

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Re: Proposal and RFC left hand rear brake
« Reply #4 on: December 05, 2017, 04:32:49 AM »

Quote
To have functional rear brakes lever and pedal you need this:
Interesting. It is just a one way valve to allow pressure to come from the hand brake but not go back to the hand brake reservoir. Apparently you can feed pressure into the rear cylinder reservoir port and then the front handbrake becomes the reservoir. I'm not sure this valve would fit the J Juan cylinder but maybe. Who's going to try it?
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Specta

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Re: Proposal and RFC left hand rear brake
« Reply #5 on: December 05, 2017, 04:33:43 PM »

That would be the best solution.
Another way is to remove the foot brake and connect directly the handbrake to the caliper.

In any case beware of the master cylindre piston size. 13 mm will be too big : hard to press.
To have the same feeling than the front brake you have to respect the same surface ratio : master piston surface / caliper pistons surface = 0.088
That means your rear hand brake must have a piston around 10 mm.
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ButchtheBARFdude

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Re: Proposal and RFC left hand rear brake
« Reply #6 on: December 06, 2017, 06:20:53 PM »

I had a Recluse hand rear brake installed on my Alta MX. The increased control is just incredible. I'm going to do this on my gas dirtbike.
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