I have a 72 Cuda and I'm upgrading to 73 Cuda disc brakes and hoped someone can provide some guidance for installing this disc brake hold off valve.

Basically which brake lines go where and how? It has 3 ports Thanks

Here ya go.

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As per attached article "the metering valve holds off pressure to the front brakes under light braking to minimize front wheel skids on icy or wet roads"



That seems to me to be contradictory to the current mantra of putting newest tires on the rear to prevent spin outs on wet roads. I personally don't buy the new tires on rear theory, but then drivers are getting gradually dumber.

Didn't have ABS back then

that changes the equation.

Thanks All, I'll study this info in depth later. I was told I didn't need the proportioning valve?

Yes you do, BUT!

are you changing from all drum? or did it already have disc fronts, just a smaller size?

if changing from drum to disc, then you have to change to a disc/drum prop. valve.

If changing from disc to disc then you should be able to use the original prop. valve.

I'd just eliminate the prop. valve and install a manual valve in the brake line to the rear brakes. Oh ya, that's what I DID do.

Yes, it does, all the more reason for better tires on the front now, since rears aren't going to lock up.

Rears aren't gonna lock up? I'll leave that one alone.

Please don't, by using the word "now" in my comment, I'm referring to today's cars with, I assume working "abs", and the rears shouldn't lock up, am I mistaken?

BIG difference between 'aren't' and 'shouldn't'.

Then, which is it?

'shouldn't'

If something is wrong, then they will lock up. Such as rusty drums after the truck hasn't been driven in weeks, but only on the gravel driveway.

I've had them even get a SOLID pedal on the '92 Dakota that I bought new. Absolutely NO brakes at all. Only did it once, on a rainy day towing the boat, never found out why.

That is a early valve for the early disc brake cars, 73 uses a combo proportioning valve and does not use that valve.

So with the 1972 Drum brake valve and the additional valve pictured adding the proportioning valve would complete the valving needed for even my 73 Disc brakes correct?

The problem with factory prop valves is they're just a guess. Check the parts book and you'll find the same prop/combo valve used in a plethora of models with different front/rear weight bias.

One-size-fit-all is good from a production standpoint but can't possibly prevent rear wheel lockup in all instances.

My 71 Imperial did
Gus

Is any of this objectively necessary, or can you just run a tee off the front circuit and a single line with a prop valve for the rear circuit?

This has been hashed out over and over.

Rather than rehash it here, it's in the search function btw, I'll sum it up. All the manufacturers spent considerable time and money developing them. Does that answer the question?

Not entirely true.

Case in point, my 87 Diplomat could have had one of two combination valves. One for 10" rear drums, the other for 11" rear drums, both with the same front discs and M/C.

That kinda proves Kunkel's point, if that difference in drum size requires a different spec valve, how the heck does, tire size, tire TW rating, tire pressure, passenger count, trunk loading, speed, weather, road surface, fuel load, etc factor in?

No it won't be the same as using a later distribution/proportioning combo valve. I know what your wanting to do with minimal brake line work by using that valve but it's not a good idea unless you use the early proportioning valve with it.

The best course of action is to use all 72-73 stuff or all 70-71 stuff...master cyl, brake lines, distribution/proportioning valves. I know it requires new brake lines and is a PIA. Call Fine lines and have a new fresh properly working disc brake system. It's worth it in the long run, the investment in proper factory parts that we know will work well together.

Sure you may be able to do it with a adjustable valve, but we know factory stuff works and real good.

Adjustable proportioning valves...

I have them on both of my E body's. There in the rear lines to reduce even farther the rear brake pressure and makes a big difference on how the cars brake. They make the car brake very "flat" and all four will lock at about the same time. That's how you adjust JCC for varying amounts of weight and where it is placed in the car.

One time I did a big burnout and then looked up and had to stop fast and the car did with all 4 skidding just a little. It was a awesome stop for a factory disc brake car and I could not have done it without the rear proportioning valve and the sticky goodyear eagles. (pretty much stopped doing burnouts on the street after that one )

I just can't see you getting that same performance using a drum brake distribution block and that metering valve.

Edit:
Since your car is a 72 and your using 73 disc brakes, then I would use use all late parts and not use the metering valve that was used on early cars. Don't mix brake parts because there not all the same IMO.