Ok, I have the rest of the weekend off and I plan to finish my CBB project. To recap I have the large diameter calipers with 12" Vette rotors in the front, and I have Caddy rear discs in the back. I am planning to run my stock combination valve (off of a 4-wheel drum car) and an adjustable proportioning valve. I plan to plumb and mount the proportioning valve right below the MC and before the combination valve. This is mostly for convience of mounting and plumbing. Will this work, or will I be violating a part of the Geneva Convention by doing this? :confused:

My goal is to drive the car to the Northern Chevelle Gathering next weekend!!! graemlins/thumbsup.gif But unless I call in sick all of next week, and I find 5 friends that are master mechanics and willing to work 16 hour days, I don't know if I will make it. :(

Thanks.

You have to put the proportioning valve after the distribution block. If you don't the pressure differential between the full pressure front and reduced pressure rear circuit will "trip" the safety switch in the distribution block and cut off the rear brake circuit. It will also turn the warning light on because it sees the pressure difference between the front and rear lines as a leak in the rear circuit. I found this out after installing my proportioning valve between the MC and the distribution block (from a 4 wheel drum car). I didn't think it through. Sure enough, first trip out I stepped on the brakes and the dash warning light came on-- I knew right away what the problem was and kicked myself for not seeing that during the install. With the proportioning valve installed after the distribution block, the distribution block sees equal pressure between the front and rear circuits and you won't have this problem. I moved the proportioning valve to the rear brake line after the distribution block and no more "BRAKE" warning light turning on during stops.

Also, check and double check there aren't check valves / residual valves in either side of the distribution block, or your discs will drag.

Troy

seems like you could just run the adjustable valve without the combo valve.

From reading all the stuff on proportioning / combo valves on masterpower's web site, the only thing you would be missing out on is the pressure sensor "brake failure" light.

I know the disc/drum combo valves have a drum pad hold off (residual press) and disc delay feature, but I don't think the drum/drum combo does anything other than proportion (like the disk/disk).

Is there any other reason to have the combo valve in there, other than not having to set the adjustable valve right away?

Troy,

As I was typing the question that was exactly what I was thinking. Oh well.

Charles,

I was thinking the same thing, but I was trying to use the stock combination block just because it looks clean and I already have new stainless steel brake lines that line up right to the factoy block.

My next question is, I have two factory combination blocks (which is just a distribution block and a brake light switch I think) and when I try to dissassemble them I can't get the piston to move? Am I doing something wrong???

Thanks.

It is pretty well a non servicable item.

Troy;