Brake pedal ratio

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Kahuna
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Brake pedal ratio

Post by Kahuna » Mon Nov 10, 2014 3:12 pm

Can someone advise me on the correct pedal to master cylinder ratio for a car WITHOUT power brakes?
Thanks so much
Jim

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Re: Brake pedal ratio

Post by miniv8 » Mon Nov 10, 2014 4:55 pm


Kahuna
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Re: Brake pedal ratio

Post by Kahuna » Mon Nov 10, 2014 6:21 pm

Thanks, MiniV8, but that's not quite what I was looking for. There is a recommended ratio of something like 5 or 6 to one, as I recall. Just trying to get the right one
Thanks again
Jim

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Re: Brake pedal ratio

Post by BirdMan » Tue Nov 11, 2014 11:23 am

I just measured a 1964 Falcon and brake cylinder post is 2" down from pivot and center of foot pedal pad is 12" so 6 to 1 I guess.

On my '64 Ranchero with single master cylinder I installed the power brake dual master cylinder from a '71 Cougar along with the disc brakes from it but not the power brake booster. The pedal was harder to push but not Too hard for me. The original Falcon size is 7/8" or 15/16" I think and the Cougar is 1" or 1-1/16" so larger is why pedal pressure was up as I expected to be.
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Re: Brake pedal ratio

Post by Kahuna » Tue Nov 11, 2014 4:20 pm

Thanks so much. That really helps me
Regards
Jim

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Re: Brake pedal ratio

Post by pitts64 » Sun Nov 23, 2014 8:48 am

6 t0 1 but 7 to 1 is better...

I run 6 to 1 with a power brake booster because my motor only makes 10" at idle.. It works...

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Re: Brake pedal ratio

Post by governor » Sun Nov 23, 2014 4:56 pm

If you can't get the ratio you desire you can always use a little smaller master cyl bore which will increase the pressure and provide more
stopping power.

We do this all the time on circle track cars to get the front to rear pressure balance that we need.

Gov
a passion for racing

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Re: Brake pedal ratio

Post by Kahuna » Mon Nov 24, 2014 8:56 pm

Thanks Governor
That's going to be my next step, I think
Jim

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Re: Brake pedal ratio

Post by Warpspeed » Tue Dec 09, 2014 3:46 am

Pedal ratio really has more to do with stroke at the end of the pedal than anything else.

You want to be able to stroke the master cylinder over its full range of travel, and end up with about maybe six to seven inches of pedal travel to the floor.
Much less travel than that and pedal effort increases, much more travel, and the brake pedal will end up being so high off the floor, it just won't feel right. If you are tall, with long legs, a bit of extra travel may not feel quite so bad.

The actual pedal ratio depends on the master cylinder stroke, and that can vary a bit with design, but is often around one inch.
So your actual pedal ratio might end up in the range of something like 5:1 to 7:1
Cheers, Tony.

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Re: Brake pedal ratio

Post by af2 » Tue Dec 09, 2014 5:06 pm

Warpspeed wrote:Pedal ratio really has more to do with stroke at the end of the pedal than anything else.

You want to be able to stroke the master cylinder over its full range of travel, and end up with about maybe six to seven inches of pedal travel to the floor.
Much less travel than that and pedal effort increases, much more travel, and the brake pedal will end up being so high off the floor, it just won't feel right. If you are tall, with long legs, a bit of extra travel may not feel quite so bad.

The actual pedal ratio depends on the master cylinder stroke, and that can vary a bit with design, but is often around one inch.
So your actual pedal ratio might end up in the range of something like 5:1 to 7:1
That is a point you need to take and can be done with an empty master......
GURU is only a name.
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Re: Brake pedal ratio

Post by cjperformance » Tue Jan 13, 2015 7:32 am

Kahuna wrote:Can someone advise me on the correct pedal to master cylinder ratio for a car WITHOUT power brakes?
Thanks so much
Jim
What car, what brakes & what use?
Craig.

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Re: Brake pedal ratio

Post by af2 » Tue Jan 13, 2015 7:18 pm

cjperformance wrote:
Kahuna wrote:Can someone advise me on the correct pedal to master cylinder ratio for a car WITHOUT power brakes?
Thanks so much
Jim
What car, what brakes & what use?
No kits.... Forget car,brakes and all..
GURU is only a name.
Adam

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Re: Brake pedal ratio

Post by cjperformance » Tue Jan 13, 2015 7:34 pm

af2 , has this project/op's question been scrapped?
Craig.

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Re: Brake pedal ratio

Post by af2 » Tue Jan 13, 2015 8:29 pm

cjperformance wrote:af2 , has this project/op's question been scrapped?
Not as far as I know..... If he needs help I am within 30 miles.
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Re: Brake pedal ratio

Post by cjperformance » Tue Jan 13, 2015 9:06 pm

You're a little closer than me then!
Craig.

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