brake proportion valves

[Brandy]

Will the valve off of my 67 Coronet 500 ( drum brakes all around) work with disc front/drum back? Anyone know a good supplier for brake line materials?

 

[lewtot184]

it's a distribution block and doesn't really proportion anything; otherwise it should work fine.

 

[Brandy]

The reason I ask is because the list of different parts donor cars for the swap says to be sure to get this from the car you pull the parts from. If it's the same why get the parts car unit?

it's a distribution block and doesn't really proportion anything; otherwise it should work fine.

 

[lewtot184]

i've been thru your question about parts with folks and never got a decent answer from anyone. the distribution block you have has a "saftey" built into it to tell the driver if there's a problem in the system. it's just a small rod that makes contact with a switch if the front or back hydraulic isn't working properly, very simple. proportioning is biased by the springs in the master cylinder that control the two pistons. i did a front disc conversion on my '65 coronet and don't use a proportioning valve, distribution block or any gadget. it's simply broke into a front-back system letting the master cylinder do the brain work. seems to work fine.

 

[440+6]

lewt is right on, the master dose it all and the distribution block only tells you if the pressure is different between back and front systems.
Not sure about drum/drum but disk/drum should have a hold off valve for the rear drums, it stops flow to the rear when it reaches a certain pressure, as you continue to brake harder it applies more to the front only.

I have never had an adjustable proportioning valve in any of my old cars.

 

[lewtot184]

when i did my disc conversion i bought all the junk and listened to all the hype. wasted a lot of money and time.

 

[Brandy]

I hear you. I try to always stand on the shoulders of all you guys that have already done this stuff. If the car i'm pulling the discs off of has 4 wheel disc I might take it all. I'm using 15 inch wheels so no problem there. I know it wont make a hill of beans as far as stopping goes to have rear disc but it will look nice.
Thanks for your help guys! Randy

when i did my disc conversion i bought all the junk and listened to all the hype. wasted a lot of money and time.

 

[dpstark2]

In later years, the combo valve did have a proportioning valve built into it for disc/drum applications. In 67 drum-drum cars, you may not need to add your own when doing this swap. Some later disc/drum cars had a metering valve to the front brakes as well.

There's a lot of misinformation out there, so take some time to read up on both types of valves. A metering (or hold-off) valve acts to keep pressure out of the brake system until it builds to a certain level, like 200-300 psi. This is usually used with front brakes and the purpose is to allow rear brake shoes to come in contact with the drums as you press the pedal and synchronize application of front and rear brakes. A proportioning valve is used to reduce pressure applied to a system. There are two types. The type used in our cars allows full pressure to pass to a system until pressure reaches a certain point (like 300 psi), it then only passes that pressure plus some small proportional amount of the total pressure. The point here is to counteract the self energizing characteristic of a drum brakes and keep the rear brakes from locking up early.

In short, if you're doing this conversion, you might plan to plumb an adjustable proportion valve in line to rear brakes. You can always open it up, but most likely you'll need it to adjust bias.

Here's a good start for reading material.http://www.ecihotrodbrakes.com/brake_facts.html

 

[Brandy]

Thanks dpstark2, that was a very informative page and I saved all of the pics to a folder I have for the Express. This answered all of my questions.

In later years, the combo valve did have a proportioning valve built into it for disc/drum applications. In 67 drum-drum cars, you may not need to add your own when doing this swap. Some later disc/drum cars had a metering valve to the front brakes as well.

There's a lot of misinformation out there, so take some time to read up on both types of valves. A metering (or hold-off) valve acts to keep pressure out of the brake system until it builds to a certain level, like 200-300 psi. This is usually used with front brakes and the purpose is to allow rear brake shoes to come in contact with the drums as you press the pedal and synchronize application of front and rear brakes. A proportioning valve is used to reduce pressure applied to a system. There are two types. The type used in our cars allows full pressure to pass to a system until pressure reaches a certain point (like 300 psi), it then only passes that pressure plus some small proportional amount of the total pressure. The point here is to counteract the self energizing characteristic of a drum brakes and keep the rear brakes from locking up early.

In short, if you're doing this conversion, you might plan to plumb an adjustable proportion valve in line to rear brakes. You can always open it up, but most likely you'll need it to adjust bias.

Here's a good start for reading material.http://www.ecihotrodbrakes.com/brake_facts.html

BTW, one reason I'm wanting to get the skinny on this stuff is that my fuel tank is going in the trunk, above the axles. 25gallons of fuel weighs roughly 200 lbs. and that will shift forwards during braking thus changing the bias. Even with built in baffles it will be handling a bit different. I think an adjustable one is in order.