dual master brake question

norville · Post by **norville** » October 29, 2006, 4:50 pm

Hey folks,

Will a 1972 f250 disk/drum brake dual master cylinder work with my drum/drum system on my 65?

Heres the story. I'm upgrading to power discs in the front in the spring. So I threw on a new booster and a dual drum/drum for the winter. I do not have a working garage. But after a week plus of trying to bleed the system and finally getting someone to pump for me. It's the napa master. I slapped on the old disc/drum master from the donor and it worked yeah for like an hour I must have ridden on a new spot cause now its to the floor.

So I want to upgrade to discs can I just use a disc/drum setup??? with out the proportioniing valves for now? Is there something different in the master besides the fluid resivour. Cause the disc/drum one is plenty big enough in both sections.

Help??

bob

DV65CustomCab · Post by **DV65CustomCab** » October 30, 2006, 7:22 am

Don't do it.
The internals of the master cylinder are different. The bore size and fluid requirements of drums vs discs are different and it will not brake properly...you may, in fact, have no pedal.

norville · Post by **norville** » October 30, 2006, 7:31 am

thanks

bob

MadMaxetc · Post by **MadMaxetc** » October 30, 2006, 10:39 pm

DV65CustomCab wrote:Don't do it.

He is right. The internals are differant as well as volumes.

You als NEED the proporting valve. if you don't have it most of the braking will go to the rear and just lock them up, and it will take you a LOT longer to stop. (I could go into the pysics if you want, but I will refrain for now)

I would wait to do it all at once (but I know that some times thats not an option)

Truckfarmer · Post by **Truckfarmer** » October 31, 2006, 6:02 am

Put the correct type master cylinder on! You can change it later when you goto disk/drum. A rebuilt master cylinder is what? $25? Not worth the risk to save so little.

BikerDude · Post by **BikerDude** » November 2, 2006, 10:20 am

I just swapped out my drums for a 75 F-150 brake system front to rear including power booster. While I had the front end apart I installed Enrgy Suspension urethane pivot bushings and they tighten things up nicely.

All of the original drum system functioned when I took them off two months ago. If anyone needs or wants any of these parts just let me know.