Quote:
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.