Disc Brake Conversion Dilemma

[Chasbod]

I've just about got my truck down to the frame but feel like I'm on the overhaulin show and only have a week to get everything done. I DO plan to eventually convert the front end to disc but just don't have the time to find a donor truck----unless anyone knows of any in Houston area.

The issue is I understand that I will need to change out the proportioning valve and what better time to do this than while the cab is off.

So, can I go ahead and install a disc/drum proportioning valve now even though it may be a while before I get the actual conversion done? Any issues running 4 drum in the interim? I also understand Power/No Power booster has nothing to do with the proportioning valve?

Thanks,

CB

[fordman]

i'm not going to say yes or no. i am just going to say that the porportioning vavle helps regulator the pressure to the front and rear brakes on a disc brake system.

[427blackpearl]

i did the swap on pearl,a 68' with 75' stuff.
i changed the mastercylinder to a disc drum set up and did not change the porportioning valve.
it all works good for me but it might work better another way too.
i do plan on going to 4 disc and thin i will change the porportioning valve

[FORDification]

If you're asking if you can install a proportioning valve now but continue using your drum brakes....the answer is no. Not that the brakes won't work, but they'll be very mis-matched front-to-rear, and you'll find the rear brakes will lock up pretty easily. This obviously would be disastrous if you have to made a sudden panic stop.

Just leave your current drum-brake distribution block in there while you're still using the drum brakes, and then when you find your donor truck and are ready to do the swap, get everything then and install them at that time.

[Thunderfoot]

i did the swap on pearl,a 68' with 75' stuff.
i changed the mastercylinder to a disc drum set up and did not change the porportioning valve.
it all works good for me but it might work better another way too.
i do plan on going to 4 disc and thin i will change the porportioning valve

FYI, a proportioning valve for Disk/Disk is the same as Drum/Drum... basically there is no proportioning needed for these setups so it is just a distribution block. However, you may want to use an aftermarket inline proportioning valve to fine tune the rear brakes when you go to Disk in the rear.

A Disk/Drum setup needs a proportioning valve as the drum brakes only need around 600-800lb of pressure to work and the Disk need around 1200lb of pressure, so by the time you get enough pressure to lock up the fronts, the backs locked up half a block earlier and the back end is trying to pass the front.

The proportioning valve limits the pressure to the drums in the back on a Disk/Drum setup... So installing it on a Drum/Drum setup would make the rear brakes not work much at all...

[Chasbod]

Thanks for all the replies....it's certainly makes sense to match it all up correctly---otherwise the guy doing the inspection might need to clean out his drawers when he does the braking test.

It would really be nice to get it all done with the cab off and steering gear out of the way so I may have to modify the plans a little.

[flyboy2610]

otherwise the guy doing the inspection might need to clean out his drawers when he does the braking test.

Click on Fat Albert's Car:
http://www.rhapsody.com/bill-cosby/fat-albert

[mickster]

I have a disc brake setup from a '74. But I'm not that close to Houston. 5 or 6 hours from Denison

[19FORD67]

All you need is a 1979 donor truck, which can be found in most rednecks backyards in Houston But really, should be pretty easy to find in a Houston salvage yard.

[Chasbod]

All you need is a 1979 donor truck, which can be found in most rednecks backyards in Houston But really, should be pretty easy to find in a Houston salvage yard.

That's what I thought!! But the Houston yards are all chasing the buck and only have late model stuff. They sent all the old stuff to the crusher when steel prices went thru the roof. I've had better luck calling yards outside Houston. But geez, they think all this old stuff is gold plated!