brake ? PROPORTIONING VALVE or not

using a 46 ford stock brake setup on my av8, 46 front drums, 46 ford master cylinder and all its hardware.10''ford mavrick drums rear, do i need a PROPORTIONING VALVE with this set up?

 

Depends on whether you're happy with the brake bias or not. The adjustable ones aren't too expensive and allow a fair bit of adjustment. I put one in my drum/drum set up.

Flatman

 

This site might be helpful.

http://www.stoptech.com/tech_info/wp_proportioning_valves.shtml

 

i wander how many people use one with their drum/drum setup...should i use a residual valve...

 

you probably don't need a proportioning valve , if it was my car i would try without it . but you do need residual valves...either inline or built into the master cylinder

 

Here's how it was explained to me years ago.

Imagine the wheel/tire combo as a lever. The larger the size of the lever, the more stopping power. There's some kind of math formula for this but it makes my head hurt. The real problem is the size bias between the fronts and rears. If the lever in back is too big, it does all the braking. We want both ends to work. If that's the case, a proportioning valve may be needed.

That said, most tire combos seen on hot rods are not that out of balance as to require proportioning. A proportioning valve just takes away/reduces rear brake effectiveness. It's ricky racer technology that years ago someone decided to use on hot rods. Somehow it caught on and is now sorta "required equipment". Some have made a lot of money over the years selling rodders something they don't need. I have personally had a hand in building dozens of cars over the years and have only seen 1 car that needed a proportioning valve. It had 23" tire on the front and giant 33" tires on the rear (also 15" wide) making a HUGE lever on the back that the fronts couldn't overcome. That's my story and I'm sticking to it.

 

iam using the stock 46 ford master cylinder, what size of valves are needed and how many?

 

That's backwards. The larger the O.D. of the tire, the less effective the brake is and the less likely it will be able to lock the tire.

Think of that stubborn bolt that you can't break loose with your standard length ratchet. When you grab your man sized breaker bar, the bolt starts to turn. Apply that analogy to the car, the bolt represents the brake and the longer breaker bar represents the O.D. of the tire.


Is a prop valve required on an old car??? Depends. Take your car to a safe place and thrash the brakes. If the rears EVER lock up before the fronts, then yes. If not then your doing good. Do this test with the an empty trunk and minimal fuel.

 

the stock `46 master cylinder has it built in

plumb in the 8" rear and your brakes will work fine without any proportioning valve

 

Probably dont need a proportioning valve. some say to use residual valves, but
if you keep the shoes adjusted out very close to the drums ,you can get away
without them as well.
Bottom line, how do they feel to you ?

 

thanks guys....

 

you only need residual valves if the height of the master cylinder is below the height of the wheel cylinders.

 

it will be under the floor like a stock 46 is....

 

What he says.

 

All drum drum or disc drum setup's MUST have a residual valve, on the drum side. All Original Cars with drums has them. Since the strenghts of the springs pull the brake shoes away from the drum, resulting in long pedal travel, maybe to long.

Disc brakes are another story, since there is no springs involved and can cope without residual valves. But as stated above you can need them if the master cylinder is located below the calipers.

Usually they recommend 10 psi for Drum setups, and 2 psi for disc's



And mixing Ford front brakes with Bendix type rear ones, probably needs a proportioning valve, since the Bendix type is more effective.

 

Roger what Mr 42 says. Drums need the valve, in line or built into the MC. Dont chance stopping for a $20 part.

 

with the few 46 ford setups i have went through new lines, master cyl, wheel cyl, ect. i have never seen a residual valve in the system,. .. but sence i using smaller drums in back than front, i want to be safe... ok i guess i take that back, after looking at this pic, it does have a residual valve

 

yes , the stock original type `46 Ford master cylinder has the residual valve built into it


there is no need to add any to your brake system , but if you did for some reason add a 10 lb residual valve in each front and rear lines that would be fine and cause absolutely no problems

 

sorry about that i remember you had told me that already.

 

adding these valves, would that be a good idea or leave it as it is....

 

So far, I've never needed one in lots of different combos. It doesn't mean there won't come a time when I do. Just plumb the thing without it, and see if your rear wheels lock up with too little pedal effort. Remember, they will lock up before the front because of weight bias. Point is to see if they lock up before getting ample braking from the fronts. You can always add one if needed.

 

thanks...

 

Gotta disagree here. The residual pressure valves in a drum brake system are there to stop the wheel cylinders sucking in air when the brakes are released, not to hold the shoes out near the drum.

 

This is some good information - Article from Rod & Custom.

Cheers!

Neal0o

 

Looked at your car today at El Tom-os . Looks killer !!!!
Drum to drum and the residual valve is in the master cylinder.
Should stop without any additions.
Lets get er done so you can drive down to "beatersville " in May.....

 

iam ready to do just that, got it home today getting started on the paint and brakes....

 

alot of great info....good read

 

you dont need any valves with a 46 ford m/c. it does it all.