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Manual Master for disc/disc '73 barracuda #3078697
09/19/22 12:00 PM
09/19/22 12:00 PM
Joined: Aug 2011
Posts: 359
mississippi
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lostdog Offline OP
enthusiast
lostdog  Offline OP
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Joined: Aug 2011
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mississippi
When I started this project there were NO brakes in this car.
I thought I wanted power brakes so I bought all the pivots, clevis, master, booster, firewall support plate, and a speedway rear disc conversion (I hate this kit by the way) but anyway, my brakes work real good. I had to install a manual valve to be able to adjust the bias to the back brakes but as far as I can tell it's working fine. I am prepared to change that

I did the math and science before I bought the power brake set up and it dictates the system requires a 7/8" bore master and I have an 8:1 pedal ratio

Fast forward .... I have decided to put a blower on the engine and I want to clean up the look and go with a manual master. I would like to keep the power brake mechanisms under the dash and find a master that I can bolt up, air bleed and just go.

What suggestion do you have for a manual master?

Re: Manual Master for disc/disc '73 barracuda [Re: lostdog] #3078751
09/19/22 02:55 PM
09/19/22 02:55 PM
Joined: Feb 2010
Posts: 18,493
Granite Bay CA
Kern Dog Offline
Striving for excellence
Kern Dog  Offline
Striving for excellence

Joined: Feb 2010
Posts: 18,493
Granite Bay CA
A manual setup will need MORE pedal ratio than a power setup. It is reported that many power setups have ratios as low as 2.5 to 1 considering the linkages and such. Manual cars need a minimum of 4 to 1 but are better with higher ratios. I have a 6.6 to 1 ratio in my '70 Charger but I am also switching to hydroboost. Mine ought to stop quite well.
Dr Diff usually suggests a 15/16" bore for manual applications whether they are disc/drum or 4 wheel disc.

Re: Manual Master for disc/disc '73 barracuda [Re: Kern Dog] #3078753
09/19/22 03:02 PM
09/19/22 03:02 PM
Joined: Aug 2011
Posts: 359
mississippi
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lostdog Offline OP
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lostdog  Offline OP
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Joined: Aug 2011
Posts: 359
mississippi
Originally Posted by Kern Dog
A manual setup will need MORE pedal ratio than a power setup. It is reported that many power setups have ratios as low as 2.5 to 1 considering the linkages and such. Manual cars need a minimum of 4 to 1 but are better with higher ratios. I have a 6.6 to 1 ratio in my '70 Charger but I am also switching to hydroboost. Mine ought to stop quite well.
Dr Diff usually suggests a 15/16" bore for manual applications whether they are disc/drum or 4 wheel disc.


I actually just reached out to them a few minutes ago for a recommendation. I think I will need to add a proportioning valve too - not sure.

Thank you !







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