Front disc conversion - stock prop valve or adjustable?

[RGAZ]

73 duster front disc conversion. Forgot to get the prop valve and clearly need one. Rear was swapped to 8-3/4 from b-body so do I use the stock Duster prop valve I can get from Classic or Dr Diff or should I get an adjustable? Is there a better prop valve option maybe a B-body?

Thoughts?
RGAZ

 

[el5dart]

doctor diff sells them

 

[Kendog 170]

I'd get the 73 Duster one from Dr. Diff as suggested.
Mopar 1 Piece Proportioning Valve

 

[Dana67Dart]

What size brakes do you have on the back

 

[Divenut]

I'm using a Wilwood adjustable. Happy with it. Really allowed me to dial in the front vs rear bias.

 

[RGAZ]

10" from a 70 Roadrunner.

RGAZ

 

[-Boosted-]

With a mix-n-match setup, I would recommend the adjustable. Who knows what size the pistons are on the calipers and if they match up well with the master cylinder or wheel cylinders for that matter....

 

[RGAZ]

I'm using a Wilwood adjustable. Happy with it. Really allowed me to dial in the front vs rear bias.

Did you put it between the MC and the Dist block or after the Dist block?

 

[67Dart273]

I believe you want the valve AFTER (to the rear of) the dist block so as to keep the differential valve centered

 

[Dana67Dart]

Did you put it between the MC and the Dist block or after the Dist block

You put it after the distro in the main line to the rear brakes

Also...

If your stock distro has a prop valve built in you will either need to use the built in valve or replace the distro with a straight distro no prop valve and add the external in the brake line to the rear

 

[RGAZ]

You put it after the distro in the main line to the rear brakes

Bummer, that is down on the frame rail. Not what i would call easy access, but thanks for the info.

 

[Dana67Dart]

I just checked rock auto.


The rear drum on 73 dart 10x2.5 used a 15/16 wheel cyl


Guess what also used a 10x2.5 and a 15/16 wheel cyl.... 70 roadrunner!


I would go with the factory all in one prop valve.


73 dart

70 roadrunner

 

[RGAZ]

If your stock distro has a prop valve built in you will either need to use the built in valve or replace the distro with a straight distro no prop valve and add the external in the brake line to the rear

Stock car was 4 wheel drum and the Dist block looks like just a dist block with no prop valve in it (no side entry port) and with my recent test drive (with front disc) it was rear brake heavy (like badly) so I am sure it has no proportioning ability at all. But yes, I get it.

 

[Divenut]

Did you put it between the MC and the Dist block or after the Dist block?

I eliminated the OEM proportioning block. I believe some applications use Residual pressure valve before the rear drums. Have one, but haven't put it in yet as the brakes are working well.

 

[67Dart273]

So far as I know, NO Mopar all drum cars used a prop valve.

 

[Kendog 170]

I know I'm going to get beat up on this one, but I converted a 68 Dart to 73 front discs and left the valve alone. It worked pretty dam good. I did replace it eventually once I did a v8 conversion to it. Remember it's your life and brakes so I was just saying.

 

[340sFastback]

You can go to smaller bore rear wheel cylinders to reduce brake force on rear drum brakes.

 

[Icetech]

I went with the wilwood.. i can't tell any difference from full open to full closed though (closed is something like 60%, not 0%..)

Mounted it off one of the MC studs... quick flat metal bracket

 

[RGAZ]

I went with the wilwood.. i can't tell any difference from full open to full closed though (closed is something like 60%, not 0%..)

Mounted it off one of the MC studs... quick flat metal bracket

This is what I was going to do, but the group says mount it AFTER the Dist block which would put it way down on the rail. Could the Dist block be messing with your setup which limits your adjustability? I thought it was just passages to split the pressure.

 

[Jim Kueneman]

I know I'm going to get beat up on this one, but I converted a 68 Dart to 73 front discs and left the valve alone. It worked pretty dam good. I did replace it eventually once I did a v8 conversion to it. Remember it's your life and brakes so I was just saying.

Me too. Put '73 Dart setup on the '72 Duster with a B-Body 8.75" rear axle with 10" brakes.

 

[Icetech]

This is what I was going to do, but the group says mount it AFTER the Dist block which would put it way down on the rail. Could the Dist block be messing with your setup which limits your adjustability? I thought it was just passages to split the pressure.

No.. and mounting it after the dist block should make no difference at all (as far as i know).. it's a straight line from the MC to the rear brakes.. I could be wrong but unless someone explains why it matters without just saying do it that way.. meh.. I have seen most prop valves before the block

 

[Icetech]

This is from a hot rod magazine article..

 

[Kendog 170]

I'd prefer it after down low so you don't see it. Once adjusted you won't touch it again.

 

[Dana67Dart]

I thought it was just passages to split the pressure

It also has the brake warning switch in it.

There is a piston in it that will move to one side and short out the switch should the front or rear system fail.


This is the 67 distro. (No prop valve)

If the mc applies 100 psi to the front and 100 psi to the rear the piston assy stays in the center

If you put a prop valve before the rear inlet then when the master applies 100 psi to the front and 50 psi to the rear the piston assy moves shorting the valve

If the prop valve is after the distro the distro acts like the first example.


(These dates are approximate)

The factory 73 up distro has a prop valve built in.

The 72 down has a separate prop valve down stream on the inside frame rail.

 

[Icetech]

It also has the brake warning switch in it.

There is a piston in it that will move to one side and short out the switch should the front or rear system fail.

Depends on what you have.. if it was like mine, old drum/drum it's literally just a block with ports in it