I can't remember exactly, but with Travis' kit and Strange brakes, I recorded pressures of 1200-1300 psi on the front and around 1000 psi on the rear. Panic stop, very hard pedal pressure.
race only brakes
- Thread starter rich
- Start date
stock setup is 4:1 and Travis' moves the rod higher on the pedal.
Are you saying his is 4:1 and stock is different?
Are you saying his is 4:1 and stock is different?
Stock manual brake pedal ratio is between 6 to 7 to 1...can't remember exactly without measuring again. Stock power brakes is something like 3 to 1. Travis' kit has the pivot between the two.
Improper pedal ratio is the most common cause of poor operation of brakes. The pedal ratio must be great enough to produce 1200 PSI system pressure under severe braking conditions. We recommend using a pressure gauge connected to the system to verify the maximum available pressure before running the car. Start with a pedal ratio of 6:1 and adjust if needed.
PEDAL RATIOS / MECHANICAL LEVERAGE:
Pedal ratio, or mechanical leverage is the ratio calculated from the length from the pivot point of the pedal to the center of the foot pedal (A), divided by the length from the pivot point to the master cylinder pushrod (B). Refer to the figures below.
Mechanical leverage is simply a means of increasing the brake force without increasing your leg effort. As “A” gets longer and “B” gets shorter, the mechanical leverage increases brake force without pushing harder on the pedal. The disadvantage is that the pedal stroke also increases, requiring you to push the pedal further.
With a 1” master cylinder stroke, a 100 pound push on the pedal, and the pedal having a 4:1 ratio, the force is 4 x 100 = 400 pounds, and the stroke is 4 x 1 = 4 inches. With a 100 pound push on the pedal, and the pedal having a 6:1 ratio, the force is 6 x 100 = 600 pounds, and the stroke is 6 x 1 = 6 inches.
If uncertain about which pedal ratio is right for your application, a 6:1 ratio is an excellent starting point.
A = Distance form pivot point to middle of push / pull point
B = Distance form pivot to point of push on master cylinder
P = Pivot point
F = Force or push
PEDAL RATIOS / MECHANICAL LEVERAGE:
Pedal ratio, or mechanical leverage is the ratio calculated from the length from the pivot point of the pedal to the center of the foot pedal (A), divided by the length from the pivot point to the master cylinder pushrod (B). Refer to the figures below.
Mechanical leverage is simply a means of increasing the brake force without increasing your leg effort. As “A” gets longer and “B” gets shorter, the mechanical leverage increases brake force without pushing harder on the pedal. The disadvantage is that the pedal stroke also increases, requiring you to push the pedal further.
With a 1” master cylinder stroke, a 100 pound push on the pedal, and the pedal having a 4:1 ratio, the force is 4 x 100 = 400 pounds, and the stroke is 4 x 1 = 4 inches. With a 100 pound push on the pedal, and the pedal having a 6:1 ratio, the force is 6 x 100 = 600 pounds, and the stroke is 6 x 1 = 6 inches.
If uncertain about which pedal ratio is right for your application, a 6:1 ratio is an excellent starting point.
A = Distance form pivot point to middle of push / pull point
B = Distance form pivot to point of push on master cylinder
P = Pivot point
F = Force or push
well Todd used Travis' kit and he's anal about getting stuff right and his was within specs at the calipers. I think you'll be just fine with his kit.
anal is good when stopping not the best pics camera batterys need charged if my math is close almost a 7:1 ratio pivot to top hole 2 pivot to bottom of pedal 14" equals 7 :1
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