Anatomy of a Brake Pedal

Who ever thinks about their brake pedal?  You push it and the car stops.

Actually, there's lots of math an physics that goes into that simple concept.  I have a brake pedal from a car that had power brakes (as almost all cars have had for the last 20 years).  Power brakes add extra force to the effort applied by your leg when you press the pedal.  I didn't want to bother with having power brakes so I have to create the equivalent force another way.

It starts with the leverage being applied by the brake pedal itself.  Here is the pedal I have.

It pivots around the tube on the end and the arm that sticks-out about 1/3 of the way down pushes the brake mechanism.  In this case, the leverage is 3x.  If I push the pedal 3", the arm moves 1" but 3x harder.  Push with 50 lbs of force and get 150 pounds.

But that's not going to stop me well enough in my setup.  Without power brakes, I estimate I'll need about 6x leverage to get proper stopping forces.  My plan is to shorten the distance from the tube to the arm and lengthen the distance from the arm to the pedal.  To do this, I'll have to cut and reweld in a few places.

Here are my first cut marks.  I plan to take 1 1/2" out of the upper part.

Cut that apart.

Open up the bottom to reinsert the cutoff piece.

And reweld everything back together.  (It's just taped at this point, but you get the idea)

I just need to make sure it will actually fit in the car this way before I weld it and then install it.  By the way, the ratio is now 6.2x.