I know that the factory proportioning is under the master cylinder. I'm thinking about getting an aftermarket one, but I don't know how it would install. The aftermarket ones have one inlet & one outlet. The factory has two inlets & three outlets. I know the front and rear has one inlet each and the rear has one outlet and the front has two outlets. So how would I install the aftermarket one? Do I remove the factory one? Do I use some kind of Y to get the front lines together, if the factory one is removed? I'm putting drilled and slotted rotors up front soon and putting some rear disc off a '97 LT1 Camaro Z28 soon also and I feel that I will need an proportioning valve after that upgrade. Anyone that has one of these please shed some light on this as I'm lost. Thanks, Bobby

 

This will answer most of your questions.


https://www.thirdgen.org/newdesign/tech/propvalve.shtml

 

What about the wire that goes into the factory proportioning valve? Will I get a brake light with it loose? Whats it even for, what does it alert you of?

 

The wire is part of the brake warning system. The system is designed to detect a large difference in pressure between the front and rear braking systems. They are independent of one another due to the dual master cylinder. In the event of loss of hydraulic pressure in one side of the system, the brake light comes on. Leaving it disconnected will not result in the brake warning light being illuminated.

 

I'm not to keen on that setup in the tech section. You get alot of road vibration from a stiffer aftermarket performance suspension and your are going to have leaks in the setup in a heartbeat. There is too much weight on those hardlines from the bias valve just hanging in place and no spiral section of hardline to dampen fitting vibration. I would HIGHLY reccomend just adapting it underneath the existing prop valve on the "rears" exit (1LE J65 valve perfered) and then re-adapt it into the existing stock rear spiral hardline. Those loops are there for a reason- to dampen shock loads and prevent leaks from appearing. The J65 prop valve is a good starting point- attach it afterwards and dial down the rears from there if they are too much- leave it open fully and its still stock factory bias.

Edit: Earl's should have any brake fitting adapters you may need

 

I would like to see any pictures anyone has of there aftermarket setup.

BillyBoy,
I see what you mean about the coils. I would like to do away with the factory unit though. Maybe a brake shop could install one with some coils. I guess I'll just have to check around and see, huh?

Anyone else with any different ideas? Thanks, Bobby

 

I agree with the statement concerning vibrations and leaving the prop valve hanging unsupported. However, I would not recommend plumbing the adjustable prop valve in series with the stock one. The reason most guys install these adjustable prop valves is because the rear brake bias is insufficient to start with, and leaving the stock valve in place will cause this problem to remain.

I am in the process of upgrading my brakes. I will be installing the Wilwood adjustable prop valve, and removing the stock one. I plan to buy a prop valve out of the junkyard, and then seperate it from its mounting bracket. The Wilwood valve has a couple of mounting holes; I'm going to mount the Wilwood valve to the modified stock prop valve bracket so that it isn't just floating around. I'm then going to reflare the stock brake lines using a standard 45deg double flare, and use unions / T-fittings as necessary along with some extra line to reach the valve. It should be a reasonably sanitary install. I used a similar approach to plumb the line lock on my '79 T/A, and it turned out great. Everyone compliments the neatness of the install. Just be sure to use a good tubing bender and flare tools. I used coat hanger wire to make a "template" so that I could figure out all the bends before bending up the line.