Orange 73

I have a 73 and am replacing the master cylinder with a wilwood master. Can I just install it with the OE proportioning valve or do I need to get a new tandem adjustable proportioning valve? Thanks

Easy Mike

You're original is a pressure differential switch and not a proportioning valve. The aftermarket unit you mention sounds like an actual proportioning valve. Which do you want?

bazza77

Doesn't the Elwood unit come with adapters so you can just plug in your existing hardlines ?

It's just an expensive light weight thing that does the same as an oem unit.
If your going serious track racing with a large fuel tank you might use a manual bias control , if not then the factory set up will still be good for what most people would want.

Just my opinion

OldCarBum

Call Wilwood and ask their service techs.
When I purchased my Wilwood brakes they told me there was no need to change to a proportioning valve unless I was track racing my car with serious chassis and suspension modifications.

GTR1999

This is correct. It is only there to tell if pressure is lost in the front or rear system, then a spool is shifted and makes the switch to light the dash brake light.

Most seem to think this a pressure adjusting switch to bias pressure between the front and rear calipers. Then again some think you can tighten the lash screw on the steering box and back it off 1/4 turn and it is adjusted.

HeadsU.P.

The proportioning valve does a little more than just trigger a switch & warning light. It has a metering valve in the front of the unit and a pressure spring in the rear. In the event that either the front or rear brake system fails, loss of pressure, I believe the spool or piston is to shut off the faulty brake line so as to have the capability to still have pressure in half the system. Or a proportion of the brake fluid is blocked off until repairs can be made.
I have a diagram of the internal workings of the prop valve in my profile photo album.

The prop valve can not bias the amount of pressure going to the rear such as those needed on a disc / drum setup. That would be an adjustable type, often having a **** on the unit to tweak the braking system.

resdoggie

But a '73 doesn't have a proportioning valve as already mentioned. No need to confuse the OP.

HeadsU.P.

Really? H-m-m-m-m-m-
Ecklers. P/N # 25-162823-1 Proportioning Valve, fits 1970- 1973, $124.88

resdoggie

The car left the factory with a pressure differential switch as noted in this thread.

OldCarBum

Correct

GTR1999

Not to start an argument with anyone or anyplace, but that Eckler part is a not a proportioning valve. It is a remake of the original pressure diff switch. The pin contact is in the center of the spool in the switch. If the spools shifts from pressure loss, it makes contact and powers up the red dash brake lamp. This just reflects the way parts are sold today compared to years ago.

HeadsU.P.

Then I suggest we form a posse and ride on up to the vendor and conduct a lynching. And any other vendors that falsely label parts. We will meet at noon.
Anybody know how to tie a noose?

GTR1999

Yes I know how to tie a 13 loop hangmans noose but I would rather work on differentials, arms, and boxes.