what is the difference between residual and proportioning valve? what are the effects of both ? what arethe results of not using either? 32 fordtruck , 350 eng/trans , drum/drum brakes.
ull need 9-10psi residual for ur fronts if master is in stock position and is lower than wheel cylinders, proportion valve is something you can run on ur rears, type in residual valve under search at top and suss out the threads, i asked this ques a while back also, all ur answers will be there mate
A residual valve prevents the rated pressure of brake fluid from flowing back to the master cylinder from the wheel cylinders. It maintains that small amount of pressure on the brakes. A proportioning valve equalizes the braking pressure between the front & rear brakes.
drum/drum you probably don't need a proportioning valve. but you do need 10 lb residual valves in the front and rear lines , either built into the master cylinder or added in the lines
Thanks for the educatin. The master cylinder is frame mounted with the pedal thru the floor.Thanks Again
a proportioning valve doesn't equalize the pressure front to rear - it reduces the pressure to the rear. When you slow down, weight shifts forwards. The faster you are stopping, the more weight shift. If you have equal pressure all around, as the rear gets lighter, you would have rear wheel lockup. A proportioning valve is in the rear circuit and has a knee point (a preset pressure - typically around 600psi) at which it starts to limit the pressure. Before the knee point, the pressure is equal. once you push the pedal hard enough and generate enough pressure, the rears get less, according to the slope of the valving. So if you have a proportioning valve with a knee point of 600 psi, up to that point, f & r get equal pressure. After that, you might get 700 f and 650 r, then 800f and 680r etc etc you can get an adjustable proportioning valve that is plumbed into the rear lines and you adjust it by doing hard stops until you have the fronts locking up just before the rears do. The idea is to keep the rears from locking first, and keep one end from doing more than it needs to. Another kind of valve, is called a metering or delay valve, and i've also seen them called proportioning valve. They are used in disc/drum brakes and are around 30-50 psi and allow the rear brakes to receive the preset pressure before opening to the front brakes so the rear brakes can overcome the return springs. There are a lot of components that all have to work together.
I agree with the above except I don't believe a prop. valve limits brake pressure. I believe it slows the rate of pressure build-up but at full braking, full pressure is finally achieved.
the question is what master are u using???, im using a disk/drum master on 4 wheel drum set up ,hense why i need a residual for my fronts, if ur master already has one inbuilt then u may not need one??? proportion valve for rear is prob good idea though
A proportioning valve, beginning at the knee point, begins to limit/restrict/regulate/slow/etc the pressure going to the rear by reducing it. so after that point, no matter how much pressure you add to the pedal, it will always be less than the fronts. If you push as hard as you possibly can on the brake pedal, you might generate say 1500 psi of force at the fronts but the rears, with a properly working proportioning valve, might see 800 quick read: http://stoptech.com/technical-support/technical-white-papers/proportioning-valves the residual valve, as has been pointed out, is designed to keep a little pressure in the system when your foot is off the brake. this is particularly important when the master is below the caliper. a disc brake would have about a 2 psi valve and a drum brake a 10 psi.
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