Will the work for 4 wheel disc
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junkyardhero
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distribution ≠ proportioning
from the other posts, it appeared that you already have and aftermarket prop valve. use that.
adding other unnecessary aftermarket components to a different aftermarket system is just a recipe for problems.
master cyl ===> T-fitting ===> prop valve ===> rear brakes
from the other posts, it appeared that you already have and aftermarket prop valve. use that.
adding other unnecessary aftermarket components to a different aftermarket system is just a recipe for problems.
master cyl ===> T-fitting ===> prop valve ===> rear brakes
There is no room for the aftermarket valve without having to make lines etc thats far out of my wheel house at this point, i ordered the kit but there is litterally no space in the lines to mount the after market valve nor a damn bracket which is my main frustration a guy told me the factory disc drum valve work’s absolutely fine for rear disc conversion
I need to run a custom line from the master to t fitting? Which side of T does valve go
My understanding is 4 wheel disc does not need a proportioning valve, but only a distribution block.
That would be amazing
The valve you posted is the stock valve for a disk/drum car.
The adjustable valve that you were sent as part of your kit would be better, because it's unlikely that your rear disks were actually chosen to brake the car evenly with your front disks. The fact that you ordered a complete kit, and they didn't make the lines to include the adjustable prop valve, is poor business. If they're selling a complete, bolt on kit it should do exactly that with all of its included components.
There have been folks that have had good luck just running a distribution block. That basically just sends equal pressure to all 4 corners, and the front/rear bias adjustment is set by the calipers and rotors. Can it work? Yep, it can if the calipers and rotors match the braking needs of the car. But that depends on weight balance, tire stagger, all kinds of stuff. Can running with just a distribution block mean your brakes are biased incorrectly? Yep, that is definitely possible.
I would run whatever your brake lines fit to start off with. If it works, great. If it doesn't, well, you may need to have some work done.
The adjustable valve that you were sent as part of your kit would be better, because it's unlikely that your rear disks were actually chosen to brake the car evenly with your front disks. The fact that you ordered a complete kit, and they didn't make the lines to include the adjustable prop valve, is poor business. If they're selling a complete, bolt on kit it should do exactly that with all of its included components.
There have been folks that have had good luck just running a distribution block. That basically just sends equal pressure to all 4 corners, and the front/rear bias adjustment is set by the calipers and rotors. Can it work? Yep, it can if the calipers and rotors match the braking needs of the car. But that depends on weight balance, tire stagger, all kinds of stuff. Can running with just a distribution block mean your brakes are biased incorrectly? Yep, that is definitely possible.
I would run whatever your brake lines fit to start off with. If it works, great. If it doesn't, well, you may need to have some work done.
junkyardhero
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*shakes magic 8-ball*
"cannot predict now"
all kidding aside, without knowing the master cylinder and the caliper it's impossible to say, and even then you can only make a educated guess.
if he was running parts or a combo somebody else was running i'm sure there'd be more information available to get closer to a definitive yes or no. but i'd file this one under "better to have and not need" if i was in this situation.
Right, but I was speaking in general terms. As a rule of thumb, 4 wheel disc systems don't use a proportioning valve. That's not to say you could not plumb on in. The one in his original post though, I don't believe will work as it if for disc/drum if I am not mistaken.
Ok, i read same thing using a gutted or just drum drum distribution valve, stating that there is not a need for proportioning valve but either one would work, a mechanic of 40 years told me in his whole career he has never seen a proportioning valve on a 4 wheels disc brake car because all the pressure is equally dispersed through distribution blocks or fittings
junkyardhero
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correct, properly designed and engineered 4-wheel disc systems generally do not need a prop valve OR they have one built into the distribution block.
the devil meets the details there, with "properly designed and engineered" which, again, generally means a factory system-- not a hodge podge of parts thrown together.
@72bluNblu summed it up succinctly: there's a lot of factors that go into whether you need one or not and basically for something like this his suggestion of just putting it together and seeing how it shakes out might be the best course of action.
as to whether the distribution block from the initial post will work or not, i can't say-- if has a proportioning circuit built into it, then it would be best to avoid. if it's just a distribution block then it would be fine.
Sure, but after 40 years he may also have never seen a car that braked optimally either. Stopping and stopping as quickly as possible are two different things.
Sending equal pressure to all 4 corners only works if the brakes are sized so their stopping power matches the braking balance needed for that car.
Typically the front brakes do about 70% of the braking, the rears do about 30%. But the exact percentage depends on the weight balance of the car, the tire size stagger, etc.
The distribution block was used by the factory, and it sends equal pressure to all 4 corners. But the factory calculated the brake force needed at all 4 corners and designed the brakes to provide that amount of force with equal pressure. They designed the entire system to work correctly that way.
Your aftermarket kit just used rear disks that are intended for a completely different car, with rotors that were cheap and easy to fit to an 8 3/4 axle. I seriously doubt the brake force was calculated and matched to the requirements of an A-body at all, let alone one with your cars particular modifications.
Like I said, is it possible the factory distribution block is “close enough” that your car won’t be a hazard to life and limb when you stomp on the brakes? Sure, it is. Is it likely that distribution block with no adjustment is going to give you the ideal brake force distribution and shortest stopping distance? No, not really.
Gotcha well I definitely appreciate all this knowledge. Once i get it running i will be able to test the regular drum distribution block and see how it works but at least i have a starting point
I'm running Wilwood manual disc on all 4 corners of my bracket car without a proportioning valve, I can slow it down quickly without locking the wheels up.
just to make sure this is clear, the original valve like the one that you pictured at the start of this thread is a distribution block. Since there is no proportioning going on in the distribution block, you can use the old drum brake block that came on the car. I believe that your 71 Demon had a separate proportioning valve (one line in, one line out) about a foot toward the back of the car from the distribution block and the set of lines that you bought should have a line from the distribution block to the proportioning valve and then the longest line in the set goes from the proportioning valve to the hose to the rear axle. With just a little effort you should be able to install the adjustable valve that you have in place of the factory proportioning valve. This allows you to fine tune the system so that the back brakes don't lock up prematurely in a panic stop.
That is the distribution block. Isn't there a small brass block in the line just to the left of what I can see in the picture???
No just a distribution block
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