Brake pedal ratio and mlc

[TRoadster]

What ratio brake pedal and master cylinder are y'all using? I had planned on using a 7 to 1 pedal with a 15/16" bore m/c but the pedal travel is awful. So I'm thinking a 3/4" bore m/c with something more like a 5 to 1. I have Wilwood front discs but I've read that others have used 3/4" Vega m/c on Wilwoods brakes with no problems. The discs on the rear are factory Ford and shouldn't be a problem. The difference in pedal travel between a 7 to 1 and a 5 to 1 is about 2 3/8" for 1 1/4" travel. This would allow me the position the pedal better. The 3/4" m/c also has higher pressure but on the down side moves less volume. Anyone see anything wrong with this? Any advice?

 

[Baby Huey]

I chose the Vega M/C, Raybestos part # MC36300, 3/4" piston. Pedal ratio is around 7:1 I think.....I have GM metrics on the front, Furd 11X2 1/4" Drums on the rear.
"BH"
edit: I had the wrong part # changed it....

 

[Brucer]

whatever pedal you use and master cylinder, get an adjustable brake pushrod... you can tune your pedal position....


you just have to make sure your master cylinder has enough volume for your front and rear calipers, or front and rear drums, and the piston size to make up your pedal pressure..
i think its master power brakes has some good articles on thier website.

Master Power Brakes - How To's & Configurations

on my 80 chevy truck i'm using wilwood rear disks, and factory front disks and set it up as manual brakes, and using the 15/16 bore corvette manual master cylinder.. I'll probably do the same on the roadster, just use wilwoods all around...

 

[TRoadster]

BH, with around a 7 to 1 pedal ratio, your pushing a lot of fluid pressure. How does your brake pedal feel and how much movement is there in the pedal before it won't go any further? Brucer, Thanks for the info. I did some more searching and I found a site which had a chart for matching caliper area with MC bore for correct volume. According to the chart, my wilwood front calipers need a 7/8 bore. I know others are using a smaller 3/4 bore MC without and problems but... now I don't know. The difference on the chart is only .2 in/sq. Either way I need to make a decission soon.

 

[Rick]

I have the Total set up in mine and with 3/16" brake lines i have 1/2" of travel till the brakes stop the car.Brian at Total told me the M/C that they sell is a Mustang unit.You would have to ask Brian about the ratio

 

[Baby Huey]

BH, with around a 7 to 1 pedal ratio, your pushing a lot of fluid pressure. How does your brake pedal feel and how much movement is there in the pedal before it won't go any further? Brucer, Thanks for the info. I did some more searching and I found a site which had a chart for matching caliper area with MC bore for correct volume. According to the chart, my wilwood front calipers need a 7/8 bore. I know others are using a smaller 3/4 bore MC without and problems but... now I don't know. The difference on the chart is only .2 in/sq. Either way I need to make a decission soon.

LOL,I dunno........Mine's high n dry on stands, someday I'll bend up sommore lines and see if it all works. I guess for now it's jus therory. "BH"

 

[TRoadster]

Thanks Rick. I've decided to go with a 7/8 mc. It will give me a little more fluid volume without losing too much pressure. I will go with a 6 to 6 1/2 to 1 pedal ratio to make up the difference. Thanks