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Old 06-26-2017, 03:56 PM   #2
dwcsr
Hollister Road Co.
 
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Join Date: Apr 2005
Location: Houston
Posts: 6,131
Re: 1949 1 ton brakes

Quote:
Originally Posted by hillguy View Post
can i use a dorman M89160 dual master cylinder to up grade stock drum/drum brake system? do i need 10lb. checks classic parts said it would work do not get any pedal. have 1 inch travel on rod new lines new wheel cylinders no leaks? stumped
That master is to small. You will get no pedal. You will need a minimum of 1.25".

Are you using a vacuum booster? if not you may want to go to a 1.375 or 37mm bore.

We do a lot of 3/4 and one ton disc brake and master cylinder conversions and I can tell you for fact that 1/2 ton stuff that sold by many will not work on 3/4 and one ton. The cylinder bores are much smaller on a 1/2ton and you end up with the pedal you have. They then will suggest you use a residual valve to keep the pedal up. This is an attempt to fix a bad design and make their part one size fits all. You do not need a residual valve in a properly sized system unless the master is below the IN port of the wheel cylinder. Or in some odd cases you have a quick take up master that was designed for better fuel economy and then only on the drum side.
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