Disc Brake Proportioning Valve - Replacement

[Daffy_'69]

In my '69 Ranger F250, it appears I had original equipment Dual Piston Discs up front, however, it was in the junk yard long enough to rot the brake lines and valves.

I am getting most of my brake parts from my donor truck with Drums up front, obviously I will not be able to use the Prop Valve from this truck, but what about metering valve? Also, I read in another post that the Prop valve mounts on the top of the Steering box(?), but mine was on the frame rail, just aft of the steering box.

I have seen Prop valves at LMC and NPD, do I just need a Prop valve for my year of truck and some new brake line for my set up or is there something else I've missed?

Thanks for your feedback.

Cheers,

[AlleyCat]

No, you seem to be right on track.Is your original valve damaged? The reason I ask is most prop valves ( at least those used on older vehicles) were made of brass which is pretty much corrosion resistant.Unless the threads are stripped it's probably okay.

As far as location I've seen prop valves on the steering box, on the frame aft of the steering box and on the 79 F250 I just scrapped it was on the rear side of the engine crossmember beside the box.Hope this helps.

[Daffy_'69]

Thanks for the information... I was not able to save the old Prop valve from the Disc set-up, the brass was OK, but the switch was not functioning.

I have decided to get a Prop / Metering valve combination from SSBC, spendy, but it is adjustable and what the heck. I'm only going to rebuild a truck once (I hope) and why not be able to tune the brakes.

With this Prop valve, I'll be doing new lines. I think I'm going to try and mount the Prop valve in a little more accessible location so that I could actually adjust it.

Is the firewall an OK place or should it be on the frame? Are there issues with loads in the lines if the valve is not on a hard rigid mount, like the frame? Thanks for your feedback and thoughts.

I'll let everyone know how if goes when I get it installed.

Cheers,

[mnagatani]

OK, I have a picture of the valve itself and its stock location. I have a question regarding the question marks on the image. Does anyone know which "?" line goes to on the master? Thanks!

[Daffy_'69]

I can tell you where mine go tomorrow, when I go out and take a look.

Is this for disc brakes or drum, just curious. I have a drum front brake donor and that is what I'll give you the information from.

[theskytoucher]

Um both do!! There should be two outlets on your master cylinder!!!! At least that is the way all the truck i have seen have had it!!!

[mnagatani]

My current setup is for drum brakes all around. I know I have two outlets on the master, but does it matter which line goes to the front side or rear side of the master? Thanks again all

[theskytoucher]

i dont think it matters on drum but it does on disk!!! If the reservors are the same size it doesnt matter!!

[Daffy_'69]

Troy,

So for Discs, which goes size goes for the discs - bigger or smaller?

Thanks

[theskytoucher]

The bigger goes to the disks!!! They require more fluid!!!!

[AlleyCat]

The master cylinders between disc and drum brakes are different.On drum brake masters or the drum half of a disc/drum master there are check valves in the outlet ports.These hold a small amount of residual pressure (maybe 1 psi) in the lines to keep the wheel cylinder cups seated against the bores to prevent seepage.Disc brake calipers use square cut o-rings that don't require the residual pressure to prevent leaks.If a drum master is used with discs the check valves will prevent the calipers from releasing completely and the brakes will drag.

As far as mounting the prop valve you should either mount it to the master cylinder/booster assembley or to the frame ( top of steering box is okay as it's a solid frame mounted component).If you look at the lines from the master to the prop valve you will notice a loop built into the lines.The reason for the loop is to give the line some flexibility when the cab and frame twist under load.Even the most gently driven vehicle will have some flexing.If the lines are too short or lack flexibility they will eventually break.Hope this helps.

[Daffy_'69]

Clay,

Glad to hear your comments... I have a couple follow-up questions.

1) I can't assume the guy who had this rig before me did anything by the book, so to be safe I should get a new Master for a disc brake set up. Do you agree?

2) I have a 69' F250 and the brake parts I have been buying are correct for that year and model of truck, my question is, how can I tell if I have a correct master?

3) I like the idea of mounting to the master, but I do not see any obvious mount locations on the casting, am I missing something?

Anything else you'd like to tell me about making sure I have the correct set-up and then setting it up correctly, will be greatly appreciated.

Thanks again

[AlleyCat]

Doug, in answer to your questions:

1) Yes, if it were me I would get a new master for disc brakes.The time and aggravation you will likely spend to learn the master is the wrong one is far more costly than buying a new one.

2) The check valves in drum brake masters are usually built into the line seats at the bottom of the holes where the fittings screw in.These are about impossible to see.There is no real way to tell them apart.

3) Mounting the prop valve to the master is usually done by fabricating a bracket that is retained by the same studs that mount the master to the booster.I would suggest mounting the master then measuring to see if the studs are long enough to accommodate the thickness of a bracket and 2 additional self locking nuts to hold the bracket.Some guys may disagree but I think this makes a stronger set up.I would suggest you fab a bracket from 1/8" steel.

I hate to run the risk of insulting your intelligence but your (and lot of other folks) safety is involved so I'm gonna take the chance.

If you are making up brake lines they must be steel and they must be double flared.This is a Federal standard.Copper tubing and compression fittings won't withstand the line pressures generated in a hard, panic stop.

Where ever you decide to mount the prop valve make sure not to forget the extra loop in the lines.I've often bent lines around a piece of pipe or large socket to get a nice looking loop.

[Daffy_'69]

Clay,

Excellent information and I will be taking your advice. I am using new lines and they will be steel and double flared.

I'm looking forward to getting the Prop valve in so that I can start fabricating a bracket. I should be able to get the Master through NAPA or other source I'm sure.

Have a great weekend.

[Daffy_'69]

I have my new proportioning valve from SSBC (very nice). Plan to mount that on the booster Master Cylinder interface with a plate, but I have a question first.

Is the master cylinder swap from drum to disc a direct replacement, or are there adjustments i need to make to my booster or pedal travel, etc.

BTW, I borrowed a flaring tool and the new brake lines went on very smoothly.

Thanks in advance for your response.