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Pedal Ratio Chart

Baby Huey

New Member
Pedal Ratio Chart... "BH"

PedalRatio.jpg
 
Thanks to the chart I was finally able to get the power brakes that I needed on my Bucket. The original brake pedal supplied by the manufacturer was at a ratio of 2.8. After moving the linkage closer to the pivot by 1-1/2", the ratio came up to 4.8. Much better braking power now, with much more sensativity at the pedal.
 
Drum brakes need 8 to 1 pedal ratio, disk need 12 to 1, or a power booster.. I use a 5/8" bore master cyl. for disk brakes and a 3/4" for drums, and that will give the same result as power brakes, pretty much... or you may use a larger bore wheel cyl. to ease pedal effort, works the same as a power booster... only without all that line pressure, and much cheaper. NOTE: If you can lock up your tires at any speed without too much trouble, that is all you need.
 
another thing I forgot to mention, most every Master cyl, should have a piston travel only of 3/4 inch, max. I believe, so that should help you with pedal design, and have it pivot 1/2 that distance before and the other half after the pivot point, so things are not either going all up or down, to keep the push rod from rubbing on the edge of your Master cyl. that means you make the push rod longer or shorter whatever makes it clear everything.
 
Ted - How important are residual valves. When I built mine I had a disc/drum combination with 2 psi in the front and 10 psi for the rear and they worked fine. I've seen some discussion lately where people have been using all different combinations or none at all and they all say theirs work.
 
Thanks for the reference chart. I plan on 4 wheel disc brakes for my build.
 
der Spieler said:
Ted - How important are residual valves. When I built mine I had a disc/drum combination with 2 psi in the front and 10 psi for the rear and they worked fine. I've seen some discussion lately where people have been using all different combinations or none at all and they all say theirs work.
I do not use any thing in the front line because I do not want my front pads draging any more than they do now, nothing to pull them back in like with the drum setup.. I am taking the combo valve out of my system altogether, as that only cuts the rear system way down, I'll take all the power it wants to give, just push the pedal less hard. I like the drums to do most of the stopping anyway, in over 20 years, I don't remember ever changing the rear shoes, but I have been through over 8 ot 10 sets of ft. pads...My own fault for not testing the pressure to the rears better... I use two seperate master cyls, one for disk system, (slave cyl.) the other for drums with a ck valve in master...
 
Very good information .. thanks BH and Ted.

Ron
 

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