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Brake pedal ratio

Posted: Mon Nov 10, 2014 3:12 pm
by Kahuna
Can someone advise me on the correct pedal to master cylinder ratio for a car WITHOUT power brakes?
Thanks so much
Jim

Re: Brake pedal ratio

Posted: Mon Nov 10, 2014 4:55 pm
by miniv8

Re: Brake pedal ratio

Posted: Mon Nov 10, 2014 6:21 pm
by Kahuna
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

Re: Brake pedal ratio

Posted: Tue Nov 11, 2014 11:23 am
by BirdMan
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.

Re: Brake pedal ratio

Posted: Tue Nov 11, 2014 4:20 pm
by Kahuna
Thanks so much. That really helps me
Regards
Jim

Re: Brake pedal ratio

Posted: Sun Nov 23, 2014 8:48 am
by pitts64
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...

Re: Brake pedal ratio

Posted: Sun Nov 23, 2014 4:56 pm
by governor
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

Re: Brake pedal ratio

Posted: Mon Nov 24, 2014 8:56 pm
by Kahuna
Thanks Governor
That's going to be my next step, I think
Jim

Re: Brake pedal ratio

Posted: Tue Dec 09, 2014 3:46 am
by Warpspeed
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

Re: Brake pedal ratio

Posted: Tue Dec 09, 2014 5:06 pm
by af2
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......

Re: Brake pedal ratio

Posted: Tue Jan 13, 2015 7:32 am
by cjperformance
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?

Re: Brake pedal ratio

Posted: Tue Jan 13, 2015 7:18 pm
by af2
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..

Re: Brake pedal ratio

Posted: Tue Jan 13, 2015 7:34 pm
by cjperformance
af2 , has this project/op's question been scrapped?

Re: Brake pedal ratio

Posted: Tue Jan 13, 2015 8:29 pm
by af2
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.

Re: Brake pedal ratio

Posted: Tue Jan 13, 2015 9:06 pm
by cjperformance
You're a little closer than me then!