U.S.: (704) 867-5557
Toll Free: (800) 762-0057
Fax: (704) 867-7754
U.S.: (704) 867-5557
2132 Londonderry Drive
Gastonia, NC 28056 USA
Your disc brakes now have a dual master cylinder but it is only a single system. To make your Thunderbird have a dual system, you need to use a COMBINATION VALVE. In the past this feature has not been available, but now this can be added to your Thunderbird.
A combination valve incorporates DISTRIBUTION BLOCK and PROPORTIONING into one valve providing all necessary valving for disc/drum systems.
The fluid from each chamber of the dual master system enters the system by way of the distribution block. Each system is separated within this block. Brake fluid from the portion of the reservoir serving the front brakes comes into the block and is then sent out to the left front and right front caliper. The rear brakes are served in a similar manner.
The safety feature of this block is found inside where a piston rides. When the piston is "centered", fluid flows freely to the front and rear brakes. When a loss of pressure (loss of fluid) is experienced, the piston moves to close the system off where the loss has occurred, thus allowing the other system to continue to work so that complete brake loss will not occur. The piston is the part that keeps complete fluid loss from occurring. Contrary to popular belief, the dual reservoir master cylinder does not have the capability to prevent complete loss of fluid and brakes. The DISTRIBUTION portion of the combination valve is where the safety "valve" or piston closes off the leaking system.
The proportioning valve modulates the pressure to the rear brakes. The modulation is necessary to minimize rear wheel lock up found in heavy braking and to compensate for the differences in braking conditions in front disc / rear drum systems. As pressure is applied to the system full pressure is allowed to the rear drums up to a certain point. Beyond that point the pressure to the rear is reduced, preventing rear brake lock up.