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Voldemort
05-12-2009, 09:47 PM
Do you really need that stupid Proportioning valve? I know they were put there because of different braking characteristics between disc and drum brakes. But, If it is messed up couldn't you us a hydraulic T valve for the front and just run the back straight from the Master cylinder? I mean what would it hurt to do this? I just went through a massive brake issue with a family member's car and Ihave been thinking about it, I have no plans of doing this just wondering.

cher96
05-12-2009, 10:26 PM
I'm sorry... This I know absolutely nothing about.

Mudderoy
05-12-2009, 11:12 PM
Proportioning Valve
The proportioning valve is designed to prevent rear wheel lockup during panic braking. It is needed for two main reasons - most vehicles use drum brakes in the rear and all vehicles experience weight transfer during a panic stop. Rear drum brakes are hydraulic over mechanical in design. If too much pressure is supplied to the wheel cylinders, lockup will occur. All vehicles, those with both rear drum and rear disc brakes, will experience weight transfer during a panic stop. When weight is taken off the rear wheels during a panic stop the tendency for the rear brakes to lockup will increase. The proportioning valve is designed to limit the pressure to the rear brakes during a panic braking situation.

Full info here (http://www.babcox.com/editorial/bf/bf50014.htm)

Voldemort
05-13-2009, 10:35 AM
Full info here (http://www.babcox.com/editorial/bf/bf50014.htm)

Great info bro thanks. But, it really did not fully answer my question. Which is Can you have a good braking system with out it? I mean when did they start using them? Some older cars with hydraulic brakes did not have them, Right? So you could go with out it?

Mudderoy
05-13-2009, 11:38 AM
Well I don't know, but based on what I read I think locking up the rear wheels in a extreme braking situation would be a bad thing wheather you were on the street or the trail.

I had my XJ do a 360 a couple of years ago and the only bad thing was $1500 of body repairs, I didn't hit anyone so it was only my vehcile damage I had to pay for. This was due to rain not the valve.

Maybe someone will offer an informed opinion, but I'm sticking with mine. I need all the help I can get! :smiley-scared002:

Howler_GT
05-15-2009, 04:17 PM
What you are asking is can the flow rate of fluid to the rear be decreased as to evenly distribute the braking force.

Yup it can. Best way is use of a proportioning valve.
BUT adjustable aftermarket units can be picked up cheaply through places liek JEGS and SUMMIT.

The older cars that do not use proportioning valves have drum brakes in front AND rear. Therefore the braking force is equalized.

On newer cars that have ABS brakes there are TWO inline proportioning valves as there are TWO brake lines that feed each of the rear wheels.