[bigfred1958]

Hi,
I'm converting my '64 caddy to 70+ caddy discs before Thursday for Viva las vegas...
The disc brake caddys have this valve thing that connects to the front lines. Can anyone tell me why this is there?
It looks like the valve opens up & allows more flow, but I'm not sure. Is it to hold off the front discs for a little bit so the rears can grab?
I know people that have done this conversion and not used that valve... Is it absolutely necessary?
Thanks.

[powerrodsmike]

Although the valve is not absolutely necessary for the brakes to work, It is necessary to make them work right. Does the 64 have a dual master cylinder? If it was me I would get a master cyl and a combination valve for a '70 caddy. You will have a better chance of the brakes working right. If the 70 M/C won't bolt up then try to get a m/c that will fit with the same piston diameter as the 70. The combination valve does several things, it blocks pressure to the fronts until the rears start to work,(you knew that already),I'm not sure if that part of the valve is seperate on the 70+ systems. The most noticeable effect of omitting this valve is that the fronts will lock up on loose surfaces at slow speeds. The combination valve also reduces pressure to the rears (That is the proportioning valve) and it has a shuttle valve to shut down one side of the brake system in the event of a leak. The shuttle valve has a switch for a dash light. If you do put the car together without the valve you will probably never notice until you do a panic stop or some kind of evasive maneuver. Then you will wish you had put the valve in. Hope this helps, mikey