Proportioning valve question

Mr.Spool

Well-Known Member
Already running 4 wheel disc on a failed Power master complete vacuum system ordered including the new pedal and check valve. I have a new proportioning valve, (brass), non adjustable. Do I need an adjustable proportioning valve? Here is the one I just received to replace the one that is currently running on the 4 disc with the power disaster. JEGS 631292: Proportioning Valve Disc/Disc For: 4-Wheel Disc Brake Conversions - JEGS High Performance
Do you understand the purpose of the having an adjustable propositioning valve?
 

RichieRocket

New Member
Do you understand the purpose of the having an adjustable propositioning valve?
Yes I do, to allow for bias between the pressure delivered to a particular wheel or set of wheels. In fact my old corvette was set up with bias control between each wheel independently. The original system linked right front and left rear and left front with right rear. It was changed at some point with proportioning valves to allow each individual wheel to receive fine tuning of brake pressure. So, my original question is and let me re-phrase it so it is more clear. Do some prefer an adjustable proportioning valve with these cars or do the fixed valves work fine. If adjustable is preferred, what bias is preferred? 60% front, 40% rear? Etc…
 

Mr.Spool

Well-Known Member
Yes I do, to allow for bias between the pressure delivered to a particular wheel or set of wheels. In fact my old corvette was set up with bias control between each wheel independently. The original system linked right front and left rear and left front with right rear. It was changed at some point with proportioning valves to allow each individual wheel to receive fine tuning of brake pressure. So, my original question is and let me re-phrase it so it is more clear. Do some prefer an adjustable proportioning valve with these cars or do the fixed valves work fine. If adjustable is preferred, what bias is preferred? 60% front, 40% rear? Etc…
Depends on how much power you need to hold back at the line.
The rear brakes actually hold the car when trying to foot brake it.
Adjusting the pressure to add the rear will increase holding power.
You have to find out what you need by testing.
But beware too much pressure sent to the back can make the ass try to come around you when you're trying to slow the car.
Their is a compromise
 

Chuck Leeper

Toxic old bastard
Staff member
The brass valve is supposed to prevent total loss of braking should a loss of fluid occur.
The adj prop does not do that, as it has no shuttle valve in it.
The Wilwood I have, allows for a partial increase/reduction on the rear brakes.
AIRC, my conversation with the Wilwood tech revealed it could reduce the rear psi about 58%, max.
I set mine with a panic stop, while looking for rear lock up. I adjust until I get lock up, then shut it down as required.
Obviously, tire diameter, contact patch, brake size, and ft/rear wt all come into the picture.

Back under my rock;)
 

TurboWh1

Well-Known Member
Double check to make sure the original steel one has been replaced at some point or roll with some sort of new one. I learned that the hard way:)
 
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