I have been checking in serveral places and in many threads as to what Proportioning Valve is. If anybody knows or has a picture of one i would really appreciate it if you could tell me. I kno it has something to do with brakes from what i have read in the threads i just would like to know what it is. Another car word that needs defining. Thanks if you can help. :hail:
SaSc (sassy)

 

It controls the braking pressure from back to front. The fronts ususally have around 70% of the braking power and the rears around 30%. That is the proportioning valves job to work things out. You can buy adjustable proportioning valves for speacial brakes setups like Bear and etc that allows you to set the braking distribtuion manually too, but are very expensive. But a drum brake rear and a disc brake rear use different proportioning valves due to different braking application between the two systems. Hope this helps?


By the way...welcome to the boards too!!!!

 

That's what it does.... basically it controls the timing and fluid volume delivery to the fronts vs the rears, so that the braking effort is applied evenly to both..... as far as what it is, look at your brake master cylinder; immmediately underneath it is a block of metal with about 4 or 5 lines and an electrical connector (that works the "Brake" warning light); that's the object in question.

 

I was told on my rear disc swap that the rear disc's proportioning valve doesn't really do any proportioning; that all 4 calipers get equal brakes. Supposedly it's just a housing to allow for the split of the front brake lines, and to give the brake warning light switch a place to go.

 

Not 100% sure, but I would think that if all 4 tires had equal braking power it would cause the rears to lock up to easily????

 

Hello i doubt that any of you are going to read this post after you have already responded to it, but i just wanted to thank you for taking your time out and explaining it to me. Its a warm welcome to this board everytime i sign in. Been checking out this board for a while....its great. thanks again
SaSc (sassy)

 

just want to say welcome to the boards as well

and to go a little further in depth here

when you hit the brakes notice how the nose dives and the rear end comes up a little bit?

that is mainly due to more weight being transfered to the front tires
this will allow the front tires a little more grip then the rear.
if front and rear had the same amount of braking force then you would lock those rear wheels up VERY easily because most of the weight has been transfered away from them.
so the valve allows more braking force up front since they are carrying more load and have more grip

kinda like when you take a turn very hard it is generally the inside wheel that spins
reason is because the weight is being shifted to the outside tire lifting up on the inner tire.


and again welcome