Brake pedal ratios

[JiI]

Gang, I was reading that a standard powered assist brake setup is usually 4:1 and a non-assist should never go over 6:1. Isn't a stock bug 4:1? Is the 4:1 ratio on a bug low due to the lower weight of the car?
Jeff

[dustymojave]

I just measured the forged 1965 pedals on my buggy. I got the following:

- 1-3/16" from the floor to the pedal pivot centerline
- 2-9/16" from the floor to the pushrod centerline
- 9-5/16" from the floor to the center of the brake pedal pad

This was quick measurements with a tape measure and limited access due to a front cockpit panel forward of the pedals. So if anyone wants to argue the accuracy of those, go 'head on.

- 9-5/16" - 1-3/16" = 8-1/8" pivot to pedal
- 2-9/16" - 1-3/16" = 1-3/8" pivot to pushrod

- 8-1/8" / 1-3/8" = 5.9
- 5.9:1 pedal leverage ratio

I had figured this all out many years (decades) ago when I was building that buggy to calculate the brake modifications. The trophy for a championship won with that car tends to show my calculations panned out.

What is it you're planning that you need to know the pedal ratio?
_________________
Richard
Offroading VW based cars since 1965
Tech Inspection 1963 - 2012 SCCA/SCORE/HDRA/MORE/MDR +
Retired from building Bajas, Fiberglass Buggies and Rails in the Mojave Desert. Also Sprints & Midgets, Dry Lakes, Road Race cars. All types New and Vintage
SoCalBajas Member
Kicked Cancer's A$$...1st and 2nd round...Fight ain't over yet.

[JiI]

Thanks for the info. I'm running 2 master cylinders: One 1" mc for a Ford Mustang II front end and a second Type 2 mc for the rear disks. I'm setting them up separate so the rear end will be removable in one modular section. It's for a crazy project I've been working on for a few years. I need to calculate the linkage and ratios to make them adjustable without a proportioning valve.
Jeff