Brake pedal ratio

Hoghead

Gold forum user
Messages
570
I am calculating brake bias and line pressures for a disc brake mod

What is the brake pedal ratio? I have read 3.7 and 4.6 and would like to hear from someone that really knows as I am designing this from afar and cannot go measure for myself

Before I reinvent the wheel, is there a DYI mod to increase the ratio?
 

Tweak

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CAT Member
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64
Contact Tom Hall at tigerengineering.net

He does awesome work on the pedal assembly and knows the ratios and more.
 

modtiger

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CAT Member
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4
Brake Pedal Ratios

The OEM Tiger/Alpine brake/clutch pedals have a mechanical ratio of approximately 4.4:1. I've been making kits for quite a while that modifies this ratio to 6:1, which is pretty much the standard aftermarket ratio. This gives you an advantage of about 1.36 over the OEM Pedal. This is almost as much as the vacuum booster gives you.

I also make this kit for several master cylinders from the OEM Girling to "new" Dual Masters from 13/16 to 1" diameter. Using a 13/16 diameter also increases your hydraulic ratio. The kits are complete, but you must send me a Tiger brake pedal (Alpines have a different bend) and the Pivot assembly. I can bend an Alpine pedal to near Tiger specs, but not "perfect". The process is reversible with the exception of the Pivot which I modify. I typically make several a year for Dale's customers.

I have also run my 6:1 kit with a booster and autocross pads, but be sure your seatbelt is fastened.

modtiger@comcast.net for further info.
 

Hoghead

Gold forum user
Messages
570
The OEM Tiger/Alpine brake/clutch pedals have a mechanical ratio of approximately 4.4:1. I've been making kits for quite a while that modifies this ratio to 6:1, which is pretty much the standard aftermarket ratio. This gives you an advantage of about 1.36 over the OEM Pedal. This is almost as much as the vacuum booster gives you.

That will do the trick with, and on paper at least, makes a huge difference in a non-boosted car.
Given the ability to change the pedal ratio, raises more questions:

What is a reasonable leg pressure on a street car to achieve max braking?

What deceleration rate can a street Tiger with "good" brakes achieve? I have been using .86 g as a WAG

My other WAG is the centre of gravity height. A better idea of the actual number would be a big help
 
Last edited:

michael-king

Gold forum user
CAT Member
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4,132
What deceleration rate can a street Tiger with "good" brakes achieve? I have been using .86 g as a WAG
?

It really depends on how fast you are going and how far/heavy the car in front of you is and what speed you hit it at. ... :eek:. .....

Sorry not helpful. :eek:
 
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