1949 1 ton brakes

[hillguy]

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

[dwcsr]

Originally Posted by hillguy

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.

[mr48chev]

According to this that one is 1-1/4 bore. http://www.rbinc.com/p-15166-m89160.aspx

It would at least need a residual valve on the front side.

I'm wondering if it can move enough fluid to work the drum brakes though.

We are all assuming that you have the brakes properly adjusted all the way around as out of adjustment brake shoes will need a lot more fluid and pedal travel to push them out to the drums.

[dwcsr]

Originally Posted by mr48chev

According to this that one is 1-1/4 bore. http://www.rbinc.com/p-15166-m89160.aspx

It would at least need a residual valve on the front side.

I'm wondering if it can move enough fluid to work the drum brakes though.

We are all assuming that you have the brakes properly adjusted all the way around as out of adjustment brake shoes will need a lot more fluid and pedal travel to push them out to the drums.

1.125" is 1-1/8"
1.25" is 1-1/4"