So here I sit, looking online at disc brake setups, boosters, master cylinders, hoses, tubing and the like.
One thing I would like to know is how the proportioning valves work. From what I assume, they need to be adjusted to how much pressure it takes to make the brakes work evenly and properly. Are there differences in makes? Can you use any proportioning valve on any brake system, as long as its for disc/disc/ or disc/drum applications?
Can anyone shed some light on the subject, Id like to learn how these things work.

Thanks guys!

Rich

 

Rich...check out ecihotrodbrakes.com then go to brake facts. I see a lot of guys use disc/drum setup. They use the correct mastercylinder, portional valve, and meter valves, but they forget to use a hold off valve. This is essential for disc/drum setups. It delays the front discs to allow the rear drums to actuate first. Helps stop nosedive under hard braking. Hope this helps.....Rod

 

xfordman is correct, talk to Ralph at ECI, he is a brake engineer and REALLY knows his stuff, proportioning valves do a number of things and are designed for particular types of applications, valves for trucks are different than those made for passenger due to the differences in weight bias. it is also good to consider tire diameter differences between the front and rear. during braking each tire acts a lever applying force against the brake surface, differing diameters apply that leverage at different rates. it can easily become overwhelming when trying to factor in all the variables. no place to guess at what's best. good luck, keep us posted on your findings

 

i just received a catalog from MP brakes out of Moorsville N.C. Great catalog. it goes into a good bit of detail how the brake systems work and also a trouble shooting section.

 

I ordered a powerbrake kit that bolts into the stock location, with all the valves, pedal and assembly today. I talked to the guy on the phone for about 45 minutes about my application. He added all the good stuff, and guarantees everything in the kit. Im on my way!


Rich

 

Great topic! I just purchased the disc conversion kit from Classic performance parts. The kit converts the stock Effie straight axle suspension from drum brakes to disc without major modification (basically a bolt on). The kit does not come with a proportioning valve or the other valve your talking about. My truck has the single cylinder master cylinder with power brakes. The brakes work nice right now. I don't think there is a proportioning valve in the lines. I've been told by several people I need to install the proportioning valve to adjust the brakes particularly with disc. According to the place I purchase the brake kit from. I don't need a proportioning valve, etc. Just bolt it up. I'm planning on redoing the entire brake lines in 3/16" stainless lines before I install the conversion kit. I'm not sure if I need the proportioning valve or not now?

 

Here is a piece written on the eci website. I dont know about your application, but Id call them and discuss your setup with them. Here is what their website says:

"Hold-Off / Metering Valves are used in the front (disc) system of a disc/drum brake system. They provide a "hold off" function to allow the rear (drum) brakes to actuate first. This function is very important in making the system function in the correct sequence in a rear wheel drive car. The rear brakes are always actuated first. This function is built into most factory type disc/drum combination valves. Make sure you have a metering/hold-off valve in the system either as a stand alone valve or as part of a factory valve.

Proportioning Valves go in the rear brake system (disc or drum) and provide for control of the rate of pressure rise to the rear brakes -- just the rate at which it builds up. Sooner or later the rear brakes see full master cylinder discharge pressure. The purpose of this rate of pressure rise control is to compensate for the reduction of weight on the rear wheels due to forward weight transfer during braking. In short, it eases the application of the rear brakes to help prevent rear wheel lockup. Factory combination valves have these built in -- make sure you know what you're getting, too little rate of rise is as bad as too much. You may not need one of these valves depending on the compatibility of your vehicle's brake system components.


Adjustable Proportioning Valves allow for fine tuning of the rate of pressure rise to the rear brakes if you have a lock up problem. If you have a lockup problem, experiment with the setting of the valve to eliminate lock up for all but all out panic stops. Good luck!"

Rich

 

Imlowr2,

I have built several rods some with metering and/or proportioning valves and some without. When you leave the proportioning valve out, you run the risk of the brakes not working properly if components are mismatched. On the other hand I have had brakes that worked perfectly without them. I think if yours are working well and the supplier of your kit says you don't need one, I'd leave it out.

Vern

 

Disk brakes require quite a lot more volume of fluid than drums I'd be concerned that your single rez MC won't be up to the task when the pads/shoes wear in some, plus dual chambers give a major safety margin, if one end develops a leak you still have brakes. I had a car I was driving lose all brakes when a flex line let go and it isn't something I'd care to experience again! Are you, your loved ones, and your truck worth trusting to a life critical 50 year old part compared to the price of a new MC?
The PO of our truck used the original MC for the hydraulic clutch, but I didn't trust it even for that use and replaced it with a new one. Suggestion: Don't buy MC and boosters from a regular parts house. The aftermarket hot rod manufacturers are 1/2 the price for all new.

 

A well known fact is that you can never ever use a single res " jelly jar" M/C on a dual system. Disc/Drum set ups are 2 different channels period. They act different based on pressure / volume as per explanation by AX. I would never even think of trying this. The first time your pads fade and the caliper needs to fill, the jelly jar would empty out anyway. Even on a drum/drum, the dual M/C is a good upgrade from the stock single. I second the notion on aftermarket prices, very low and a worthy investment in any car or truck.

 

Since I'm running the "jelly jar" on my truck. I also have a brake booster attached to the firewall. What would I need to do to get the right combination? Should I remove the MC and hopefully find a match to fit my brake pedal/ booster? Or just purchase the whole MC and booster kit, which is about $250.00? I've seen several on ebay going for a decent price, however I don't trust ebay on parts like that. My concern is purchasing the MC and then it won't fit, or work correctly. I definitely stop eating jelly sandwiches for a while if that were to happen.

 

Imlowr2, I would buy a matched unit from a respectable vendor and then you will not be wondering if you made the correct selection. It is really worth the peace of mind. I bought mine real cheap and got a vette cyl. as part of package. I see ads all the time for lo cost set ups. EL> However, you can always get a dual cyl with the same mount and just make sure to get the right length of rod so the stroke is correct. Not a big problem at all. My buddies just go the the salvage yard and see what is in the Fords or in cars with the same booster and then order a new one for that application. Lots of parts houses have the books with all M/C dimensions. Just look through it. Good luck