Ok I am helping a friend research his Disc brake swap on his 73 Bronco.

So far he has aquired , Nuckles rotors calipers, From a donor 78. Now he is looking for a proprting valve. Duff gets like 150.00 for them.

He is palnning on buying duffs Master cylinder/booster and bracket.

Any other options?? For the proporting valve and Master cylinder/booster and bracket.

I tried the search but didn't find anything helpfull :beer:

The prop. Valve they are selling is the distribution block/prop. valve all in one. or you can use the stock dist. block and get an aftermarket prop. valve from Wilwood(adjustable) or some other reputable source. Or grab one from a '76 F-100/F-150 as they had disc/drums stock.


Eric

You don't always need the proportioning valve. Not sure why but some Broncos work great w/o it. May just want to try it before droping the $.

thanks, I think we might just try it without. I am not sure what the proporting valve dose w a dual master cylinder anyway.

What dose it do anyway??

The proportioning valve keeps the rear brakes from locking up before the front discs. Disc brakes require more PSI to get the same amount of effective braking force than a drum brake of the common Bendix style design. With out the prop. valve the rears will see the same higher pressure as the fronts and since the rears simply reguire even less than a front drum there is too much chance of the rears locking up before the front discs get to do their job.
ok, did that make sense?;)



Eric

Sort of I just assumed that with the 2 different sections in a master cylinder that the different presure was taken care of there. not sure that mnade sense

The two resevoirs in a duel M/C are there for safety. If one circuit fails then there is still fluid in the M/C for the other. It is not set up for Proportioning. And the different sizes of some M/C's is 'cause the front circuit of a disc/drum set-up sucks more fluid into the calipers as the pads wear as opposed to self-adjusting drums which do not drain the M/C.
Make sense?



Eric

Yep, now if I can just remember that. That makes to much sense

You dont need it. I swapped a 76 D44 w/ discs into my 67, and it works great with the factory drum H block. I have the Disc proportioning valve but never even put it in, because it stops fine with out it.

Also, you don't always need to replace the master cylinder. You can pull out the residual valve on the front resivour and run it like that. Thats whats on mine now and it works great.

I had heard about that also, But my friend wants Power discss. He is running 30-9.50 15s.

Yes I know this is a Hard Core Board.

Originally posted by Pizzacutter
I had heard about that also, But my friend wants Power discss. He is running 30-9.50 15s.
Yes I know this is a Hard Core Board.

I'm running it with power. It will bolt right up to the booster. I just got the bracket and booster from BC Broncos and used my old mastercylinder.

Oh Thats good info. Unfortantly he allready bought the bracket from duff w/ the boooster and master.

I tried to explain that duff wasen't the only source but, they are convienent. (espically if its the only catalog you have, and still have dial up)

We will be starting the swap very soon, I might be looking for more help soon. Thanks for all the input