69Rman

Hey everyone,
Another project I can work on while I have lots of time, but not much money, is my brakes.
'69 Supreme, Original drum brakes, front and rear.
Got a front disc setup from the '72 Supreme parts car I had, I got most of it all cleaned up and painted, Pass side installed so far, minus new rotors.
Which proportioning valve do I need to use. The one from the '72 Supreme is a lot larger than the original one, but I thought that I had seen somewhere, that the one in pic 1 (original style) can be used with discs up front as well as drums. Can I just use this one or do I need to use the larger one in pic 2?
Thanks
Duane

joe_padavano

The first picture is NOT a proportioning valve, it is simply a distribution block with the differential pressure switch. The 67-70 factory disk brake cars used this distribution block (which is the same as the one on drum brake cars) with a separate external metering valve. The 1971-up cars used the combination valve in your second picture, which combines the distribution block with the proportioning valve to save parts count. Unless you care about a completely correct resto, use the combo valve in the second picture.

69Rman

Thanks a lot Joe!
That's what I was thinking I'd have to do. Hopefully I can get it to fit with the headers in there as well. I've never liked the look of them mounted up on the fender well. Looks kinda goofy...
Thanks!
Duane

joe_padavano

Unfortunately you will almost certainly need to move it. On AT cars I've had good luck bolting it to the top of the frame rail using one of the two holes pre-drilled for the outer support for the Z-bar. Obviously this won't work on MT cars.

69Rman

Thanks again Joe!
That does seem to be the most logical spot for it. I guess I would then have to make my own lines though. Or re bend some if possible??
I'll have to look further into this this evening.
Thanks!
Duane

joe_padavano

I've actually been able to rebend the lines without even taking them off, but since you have to put the brake system together anyway, you might want to custom bend lines that look a little neater. Simply rebending the stock lines looks a little ugly.

wmachine

On the '69s, isn't the proportioning valve mounted on the booster?

junior supercar

on 67, 68, 69 and 70 disc brake cars, the disc brake metering valve is located right under the master cylinder like you show in the picture

joe_padavano

Which is why I said this above:

The combo valve requires fewer fluid connections and thus has fewer leak points. Even with the correct 69 distribution block and metering valve, the distribution block will still likely need to be moved.

69Rman

Yes, I believe that you are correct, but, I don't have one of those proportioning valves. So I am stuck either finding one, or using the valve from the '72 in pic 2 in original post.
I plan to replace the lines, so using the '72 unit on top of the frame will work out just fine. I think.
Duane

apachemobile

I just recently replaced, well pretty much everything in the front of my 73' Cutlass Supreme. Went with this product, says its a proportioning valve. Haven't finished the brakes yet, so don't know how it performs.

http://www.inlinetube.com/Prop%20Valves/VOL105.htm

Also I have a question on what kind of clearance is needed between brake lines and headers before it becomes not safe. I'm afraid I might have reroute my new lines I worked so hard on.

JRios

I have a disc/drum set up on my 70 cutlass, what does the metering valve do? Does it keep the disc up front from locking up? or does it retard the braking effort on the rear brakes? The plunger on the rear of mine barely seems to move and gets stuck (when bleeding) can this cause poor braking?