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stress
08-18-2008, 08:58 PM
I am paralyzed from the arm pits down .I am try to get hand brakes to work on a C-Moore buggy. I have a Pilot steering mounted on a C-Moore buggy with a steering quicker and power steering, so I can get to full steering lock in about 90 degree turn of the steering wheel. I am using Pilot Master cylinders with Wilwood calipers. I do not have enought braking power, I have maybe 40% of what I need. I think I need more flow volume get the calipers to work right. The Pilot master cylinder have a small piston diameter so I get a high line pressure but low volume flow. If go to a master cylinder with large diameter piston, my line pressure will go down but flow volume will up, but I think this will require more brake lever force. Right now I am pulling on the brake lever as hard as I can and have poor brakes. There is litte room between the calipers a the rim, so I do not think I room for bigger calipers. Does anybody have any ideas what I should try ? Does my thinking about bigger diameter pistons sound right ?

Bugpac
08-18-2008, 09:02 PM
Sounds like you need a bigger master...

Bugpac
08-18-2008, 09:04 PM
you could mount a larger wilwood cylinder down below, and run a slave cylinder off the pilot master to operate the larger cylinder, be like power brakes for ya....:D

xmotorcr
08-18-2008, 11:33 PM
i'm in the same boat, i had to use a larger master cylinder when my hand controls were built.

i just found THIS (http://www.yoyodyneti.com/Product/brembo_brakes.htm) it should have no problem pushing enough fluid since its for a road race bike running dual piston, and dual calipers


I am paralyzed from the arm pits down .I am try to get hand brakes to work on a C-Moore buggy. I have a Pilot steering mounted on a C-Moore buggy with a steering quicker and power steering, so I can get to full steering lock in about 90 degree turn of the steering wheel. I am using Pilot Master cylinders with Wilwood calipers. I do not have enought braking power, I have maybe 40% of what I need. I think I need more flow volume get the calipers to work right. The Pilot master cylinder have a small piston diameter so I get a high line pressure but low volume flow. If go to a master cylinder with large diameter piston, my line pressure will go down but flow volume will up, but I think this will require more brake lever force. Right now I am pulling on the brake lever as hard as I can and have poor brakes. There is litte room between the calipers a the rim, so I do not think I room for bigger calipers. Does anybody have any ideas what I should try ? Does my thinking about bigger diameter pistons sound right ?

anasasisxenophontis
08-18-2008, 11:42 PM
Thats awesome that you still get into sand rails. Right on, man.

Kludge
08-19-2008, 11:06 AM
Hi Stress,

Where are you located?

I have a hand master cylinder from a Polaris Victory motorcycle (big V-Twin) that I'd be willing to let you try out to see if it helps.

/Frank

K-fab
08-19-2008, 02:41 PM
Smaller piston in the master cylinder makes for a longer pedal/lever throw and higher pressures at the caliper. It's the ratio of surface area from the master cylinder piston to the caliper piston(s).

Larger piston m/c will lessen the throw, but require more force to get the same amount of clamping force a smaller piston m/c can produce at the caliper.

If you need more squeeze power at the caliper, you need to go to a smaller piston master cylinder or a four piston caliper instead of a two piston caliper.

It has nothing to do with flow or volume - the displacement/movement of fluid is very little/small.

Bugpac
08-19-2008, 02:54 PM
If a way undersized master cylinder is used, it will never displace the volume of 2 large calipers tho....You still have to push the large pistons out to apply pressure, and displace all the fluid are when it moves.... what is the bore of a pilot master cylinder, 1/2" maybe?

masterfabr
08-19-2008, 03:00 PM
you could mount a larger wilwood cylinder down below, and run a slave cylinder off the pilot master to operate the larger cylinder, be like power brakes for ya....:Dgood idea

grant_wt
08-19-2008, 03:42 PM
If your lever is going all the way to the steering wheel you need to get a larger bore master. I have also heard that stainless lines can help firm up your brakes, but I have a hard time believing since you still have rubber lines which have to flex more than steel.

If your lever feels hard, but nothing happens you need to go to a smaller bore master to increase your mechanical advantage.

I also like bugpacs idea. My dad did something similar with a 2.8 v6 powered buggy he had. Stock master just gave you foot cramps you had to push it so hard, so he ran a levered push rod to a power master that sat back near the engine. You could do the same thing with a cable or a hydraulic system in between. Firefly's and similar small cars have pretty small vacuum pots that can be hidden fairly well.

Grant

LiveWire
08-19-2008, 04:05 PM
Since the C-Moore buggy gets significant influence from the Formula Cross/Extreme formerly built by Drakart then Hawk, I assume it is using the same Wilwood 4 piston calipers in the rear and small 2 piston calipers in the front with Goodridge stainless lines. I know of multiple people running Pilot yokes on the Formula Cross and Extreme and have not heard of issues with braking power. I just recently drove one and it did not stand out as having poor braking. The Formula Cross uses the smallest piston size available in the DynaLite series. If C-Moore went to a larger piston size, that could be a problem. As someone else asked, are the levers hitting the yoke?

Islander
08-20-2008, 08:27 PM
I believe that braided stainless steel lines to replace the rubber ones are what you are hearing about to firm up the braking. And yes, they do work a lot better then rubber lines, but I don't know if it would firm up the brakes as much as Stress needs though.

stress
08-20-2008, 08:35 PM
A normal C-moore buggy uses 1 master cylinder that has a 0.75 dia piston to drive both the front and back calipers. I am using 1 Pilot master cylinder to work the front brakes and 1 Pilot master cylinder to drive the back brake. The Pilot master cylinder has 0.5 dia piston. When I put the brakes on the the brake lever moves in about 1/3 of its total travel and stops and is firm. So it sounds like I need to go to a smaller piston in the master cylinder. I would like to solve my problem with the master cylinders and not have to go to different capilers, because the capilers have very little room right now. My front capilers each 2 pistons, my back capiler has 4 pistons.

masterfabr
08-20-2008, 08:45 PM
I think you're on the right track.

LiveWire
08-21-2008, 07:55 AM
A normal C-moore buggy uses 1 master cylinder that has a 0.75 dia piston to drive both the front and back calipers. I am using 1 Pilot master cylinder to work the front brakes and 1 Pilot master cylinder to drive the back brake. The Pilot master cylinder has 0.5 dia piston. When I put the brakes on the the brake lever moves in about 1/3 of its total travel and stops and is firm. So it sounds like I need to go to a smaller piston in the master cylinder. I would like to solve my problem with the master cylinders and not have to go to different capilers, because the capilers have very little room right now. My front capilers each 2 pistons, my back capiler has 4 pistons.

Your rear caliper has 4 1.380" diameter pistons. There are two calipers with larger pistons, identical mounting and setup for the same thickness rotor. They have 1.62" and 1.75" calipers respectfully. For the rear brakes, I think that is your best bet because 1 $140 bolt on caliper and you are done. Making the master cylinder larger will be no where as easy.

Your front calipers have 2 1" pistons. There are calipers with 1.12" pistons that have the same mounting dimensions. They do have threaded mounting holes instead of plain bore, but you could drill the thread out. They also have a an M10 x 1.25 inlet vs. 1/8NPT assuming yours have not already been modified to be 10x1.25. If not, you would need new brake lines or adapters. Once again, I would think this would also be much easier than trying to fab up different master cylinders.

Also, the area of 2 .5" circles is already less than that of one .75" circle. The problem may lie more in that the levers have less leverage against the pistons then the foot peddle does. It may be possible to drill a large hole for the lever pivots that is offset closer to the piston giving more leverage. You would then use a larger pivot pin as well.

stress
08-21-2008, 08:25 PM
I spend all night looking for master cylinders with a smaller piston than the Pilot and can not find anything. LiveWire the calipers you are talking about with the bigger pistons are they Wilwood calipers? I was wanting to know so I can go to the right companys website to look for the calipers you are talking about.

LiveWire
08-22-2008, 02:48 PM
Yes, Wilwood.