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Distribution blocks vs prop. valves.

AzPete

AzPete

Well-Known Member
Reading on several sites, they refer to the need of a '67 distribution block to convert a 66 to the 67 dual bowl m/c for a non power drum car. Is this a proportioning valve or a distribution valve. It seems if it is just a dist. block, it should not be so expensive as it would have no internal works. Sounds like there is confusion here.

I understand the need for a proportioning valve on a disc/drum car, but is it needed on a dual bowl drum/drum? Would the delivered pressure to each axle be that different comparing the jelly jar to a dual bowl?

I plan on this mod one day so just getting all the ducks in a row.....
 
No, the OE 4-wheel drum distribution block does not have a prop valve built into it. It does have a differential pressure switch to kick on the brake warning light in case of a fluid leak. Other than that, it's there to make a convenient place to tie all the brake lines together.

You can accomplish the same thing with some simple brass fittings, but it doesn't look as nice. The reason the OE style distribution blocks are so expensive is because they're hard to find. It's very uncommon for one to develop a problem.
 
With the original question answered, I'm gonna hijack this thread and show my own ignorance for a second.

In a dual-bowl, 4wheel drum setup, aside from the differential switch, what does the distribution block do?   When I was a youngster, I replaced my jelly jar with a dual bowl MC from some drum-brake ford from the 70's.   I wanna say a maverick.   There is no distribution block in the system at all.  Rear bowl goes to the front brakes, front bowl to the rear brakes, and never the twain shall meet.  I drove it like this for several years, without incident.

Did I totally screw the pooch? 

Not that it matters too much because I will never drive on that brake system again...every component saving the pedal will be replaced.  But still, I'd like to know if I did something wrong :)

Thanks,

Steve
 
Nope. Like I said, it's mainly for the brake warning light switch, and to give a nice pretty place to tie the brake lines together. Running it the way you are now does no harm:)
 
In a dual-bowl, 4wheel drum setup, aside from the differential switch, what does the distribution block do? When I was a youngster, I replaced my jelly jar with a dual bowl MC from some drum-brake ford from the 70's. I wanna say a maverick. There is no distribution block in the system at all. Rear bowl goes to the front brakes, front bowl to the rear brakes, and never the twain shall meet. I drove it like this for several years, without incident.

Did I totally screw the pooch?
Click to expand...

Probably not. A distribution block is needed to split the two front brakes from the MC, and another to split the two rear brakes (typically done at the rear-axle fitting).

Later on, manufacturers decided to split the braking system to LF/RR and RF/LR, which requires a completely different distribution system.
 
That was done mostly to counter braking problems with FWD cars when one half of the system fails (fluid leak). FWD cars rely on the front brakes more than RWD cars, so a front brake system failure would result in something like 20% braking ability. The counter is to switch to a cross corner split, making sure that at least one front wheel and the opposite rear wheel are working during braking. The cross keeps the car from pulling too much to one direction.
 
cool. Thanks for answering that for me. I figured I was alright, but wanted to be safe rather than sorry as I piece together my new brake system.
 
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