I have put front disk brakes from a 74 Duster on my 62 Valiant. The rear brakes are 10" drums and I used the 13/16" Dakota wheel cylinders. I've been trying to figure out what to do about a proportioning valve. It isn't clear to me that I will even need one; if I do I suppose an aftermarket adjustable proportioning valve would do the trick. Any thoughts, ideas, advice?

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

You could find a stock prop valve and see where it leaves you. Or( I recommend) A universal adj. prop valve. Put one on my 67 Dart when I went BBP and worked great,I was able to dial it in perfectly. You can go with willwood, summit, mopar...etc... or go on ebay and get a no name one for a lot cheaper(thats what I did).

You must have a proportioning valve when mixing disc brakes and drum brakes. The drum brakes are self-energizing so if you don't run a prop valve you'll lock up the rears under heavy braking or on wet pavement. That is exactly what you do not want to happen.

I did some research, and it seems that there were several factory configurations. Some had distubution block and a mettering valve but no proportioning valve. Other had a proportioning valve and no metering valve while others had both. On top of that, for some years there was a "Combination Valve." What is the difference and what do each of these do? I'm leaning toward a distribution block with an aftermarket prop valve but I'm open to other suggestions.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

David,

Inline Tube has a fair amount of info on proportioning valves, hold-off valves and so on. http://www.inlinetube.com/

I'm running my disc brake equipped '67 Valiant with the drum brake distribution block (does nothing other than act as a plumbing T), 13/16" rear wheel cylinders, but no proportioning valve. If I did have a proportioning valve I could probably use more rear brake bias under light braking. As it stands I have not been able to get any rear lockup, but I also have pretty serious tires on the car so it is hard to exceed the available grip. On my '66 Barracuda project I've decided to use 15/16" rear wheel cylinders and an adjustable proportioning valve so I may tube the system for best performance.

As anecdotes, my wife's old '72 Duster with the K-H disc brakes would lock up the rear wheels early. My '66 Dart I converted with '76 A-body brakes including the combination valve was not prone to rear lock up and stopped very well.

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Joshua

I did soe more looking on the inlinetube site... I had been there before... I found where they list specific parts for specific year/model vehicles. It looks like 69-74 A-body cars got a combination distribution block/hold-off valve - their part number BK250. They don't list a part for 75-76 A-body vehicles. I may go back and look at E, F and B body parts, just for reference.

As I understand it, the hold-off valve simply delays the application of the rear brakes but doesn't really provide any pressure metering. The above part would be an easy application because it mounts in exactly the same place and manner as the original distribution block.

The lack of a true proportioning valve bothers me a bit, especially since I have 10" brakes on the rear. An alternative is to use the BK243 distribution block which splits the front and rear circuits, and add an aftermarket adjustable proportioning valve. The total cost would be comparable and I would be able to dial in the rear brakes a little better I think.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

I have used a stock 75 up prop valve on the Valaint with both 10" drums and rear discs. It works just fine.

Its about balance within a range.....most of us are well within the range with our setups.

I have put together at least 10 modified brake setups over the years and have never found a reason to use more than a stock prop valve.

Unless you find a brake inbalance after your swap ....stay stock

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Yeah....Im the one who destroyed this rare, vintage automobile.....