Go Back   Motorcycle Forum > Motorcycle.Com General Discussion > Motorcycle Mods and Maintenance

Reply
 
Thread Tools
Old 02-12-2010, 10:16 AM   #1
rightsaidfred
Registered Member
 
Join Date: Feb 2010
Location: NC, USA
Posts: 3
Default Master cylinders

This is more of an information question and my be a dumb one. Does the front master cylinder apply more pressure than the rear? I'm building a custom bike and want to make the foot pedal control both front and rear brakes. I thought about just using a proportioning valve and one master cylinder. I am also thinking about using two seperate master cylinders, so can I use a rear master cylinder off of another bike to control the front brakes or do I have to use a front master cylinder? Any help I can get will be appreciated. Thanks, J
rightsaidfred is offline   Reply With Quote

Sponsored Links Remove Advertisements
Motorcycle Forum
Advertisement
Old 02-12-2010, 11:38 AM   #2
sarnali2
Aging Cafe` Racer

 
sarnali2's Avatar
 
Join Date: Jun 2007
Location: Sittin' down by my window, lookin' at the rain.
Posts: 8,719
Default

it's a fairly straight forward proposition Guzzi, BMW and Honda have had linked brakes for years. I would tee off the rear master cylinder and run a line to one front caliper then have the front brake operate the other, that way you retain some kind of front and rear braking control.

Actually that's not true, I wouldn't screw around with brakes myself I'd leave them separate. Having ridden bikes in the past with truly crappy brakes I've come to appreciate the wonderful stopping power on modern bikes, I'd leave them be if I were you.
__________________
"Carpe` Throttelum -Loud Suits Save Lives"

"He said he's farting because of his medication"...
sarnali2 is offline   Reply With Quote
Old 02-12-2010, 11:40 AM   #3
Kenneth_Moore
Registered Member
 
Kenneth_Moore's Avatar
 
Join Date: Jun 2007
Location: VIsiting the GIft Shop in the Pit of DIspair
Posts: 7,118
Default

Master cylinder pessure is an inverse coefficient of the square of the cylinder piston's swept area, divided by the length of the actuating rod, muliplied by the sweep of the lever in degrees. With that formula, you can quickly calculate that having a front brake lever on the throttle side of the handlebar is a really handy setup.
__________________
www.kennethmoore.org
Kenneth_Moore is offline   Reply With Quote
Old 02-12-2010, 12:31 PM   #4
pushrod
Founding Member
 
pushrod's Avatar
 
Join Date: Nov 2001
Location: Baja 'Bama
Posts: 3,642
Default

If you must have only one MC, put in the biggest one you can find, and then use a proportioning valve to balance the front and rear brakes.

But having front and/or rear brake actuation is one thing I really like about my bike. I'd customize everywhere else first...
__________________
You would not understand,
this is not how I am...

I have become -
Comfortably Numb.
pushrod is offline   Reply With Quote
Old 02-12-2010, 01:39 PM   #5
rightsaidfred
Registered Member
 
Join Date: Feb 2010
Location: NC, USA
Posts: 3
Default

The main reason for these questions is to do away with the master cylinder and brake lever on the handle bars for a cleaner look. I'm building a chopper/bobber and want the clean look, but unlike a lot of others who use no front brake, I do like to stop. Also this is only a weekend, around town bike not a daily rider. I'll leave my daily stock.
rightsaidfred is offline   Reply With Quote
Old 02-12-2010, 03:48 PM   #6
sarnali2
Aging Cafe` Racer

 
sarnali2's Avatar
 
Join Date: Jun 2007
Location: Sittin' down by my window, lookin' at the rain.
Posts: 8,719
Default

If you're building a bobber just use a drum brake on the front. All you have is a lever and brake cable. If you're basing it on a rigid frame Harley there's a ton of stuff available. The rigid frame/wide glide with ape hangers/21 in front wheel/drum brake look is total Old Skool. You'll just need to lace a star hub into the wheel and a brake drum will bolt right up.
__________________
"Carpe` Throttelum -Loud Suits Save Lives"

"He said he's farting because of his medication"...
sarnali2 is offline   Reply With Quote
Old 02-15-2010, 10:25 AM   #7
rightsaidfred
Registered Member
 
Join Date: Feb 2010
Location: NC, USA
Posts: 3
Default

Thanks for all the help guys. Actually I'm build a Yahama XS650 chop/bob. I bought the bike as a complete build, but as with many things that I have a part of the thing turned out to be a polished turd. It was pretty with the nice paint but no mechanic had seen this thing in years. I had to rebuild the carbs and re-jet them, since no one had. Every seal and gasket leaks, so the engine is out and I'm installing a new gasket set. I had to replace the front fork seals, rebuild the front caliper, and set the points, timing, and eventually bought a PAMCO electronic ignition. The pipes were so low that when I leaned into a right hand turn the bottom pipe would drag. It high centered once and that is not a fun feeling. So after seeing all of the stuff they cut corners on I'm gonna sandblast the frame and check their job of welding also. I'm not trusting my a$$ with some hacks welding job. Anyway I needed to vent and again thanks for all the help. J
rightsaidfred is offline   Reply With Quote
Reply

« Previous Thread | Next Thread »

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump