Optimal brake pedal ratio?

[chevyrestoguy]

I am playing with changing the brake pedal ratio on my '64 due to the fact that it no longer will have manual drum brakes. I converted to all 1979 Chevy C-10 suspension components, and the brakes will now be power discs.

I did some calculations on the stock pedal ratio. The pedal length is 15.50", and the distance from the pivot to the pushrod attach hole is 2.25", making the pedal ratio 6.8:1. That's too much ratio for power disc brakes.

Because I'm going to a power assist system, I need to lessen the brake ratio. If I increase the distance from 2.25" to 3.75", the pedal ratio goes down to 4.1:1, which is similar to what the factory uses for their power brake vehicles.

It would be as simple as redrilling the pushrod attach point 1.5" lower than the factory position.

Has anybody tried this (re-drilling the pushrod attach point), and what results did you get?

[INSIDIOUS '86]

I'm going to play around with this myself. I want a lot o lf pedal travel myself so that I can modulate with greater ease and precision. Get some extra pedals and try it. Let us know. I'm a little ways till I finish my project to play around like this
Posted via Mobile Device

[chevy_mike]

Originally Posted by chevyrestoguy

I am playing with changing the brake pedal ratio on my '64 due to the fact that it no longer will have manual drum brakes. I converted to all 1979 Chevy C-10 suspension components, and the brakes will now be power discs.

I did some calculations on the stock pedal ratio. The pedal length is 15.50", and the distance from the pivot to the pushrod attach hole is 2.25", making the pedal ratio 6.8:1. That's too much ratio for power disc brakes.

Because I'm going to a power assist system, I need to lessen the brake ratio. If I increase the distance from 2.25" to 3.75", the pedal ratio goes down to 4.1:1, which is similar to what the factory uses for their power brake vehicles.

It would be as simple as redrilling the pushrod attach point 1.5" lower than the factory position.

Has anybody tried this (re-drilling the pushrod attach point), and what results did you get?

I redrilled my pedal on my old '68 C10 I had years ago. For whatever reason, it seems that GM did not put the second hole on trucks but most cars they did. My '64 Chevy II wagon has two factory holes, one for manual, one for power and they are 2" apart but the pedal is shorter than a truck pedal. Never understood why GM did not add the second hole. Maybe not many added power booster as an option when bought new.

You'll be fine as long as the angle of the rod somewhat lines up with the lower hole. Don't force it down at an angle. I think most factory boosters sat at an angle for this reason. A lot of aftermarket ones don't, as they assume you will hook up to the stock manual brake hole, which is wrong.