68 Brake Proportioning Valve

[Kurt B.]

My 68 with power brakes has what appears to be a square metal block attached to the master cylinder with metal brake lines running to it from the master cylinder. I think this is a proportioning valve.
1. Am I correct in this assumption, and
2. Did ALL 68s with power brakes have this or is this optional?
Thank you,
Kurt

[Gene M.]

Re: 68 Brake Proportioning Valve

Kurt,
It is there without power brakes too.

[Phil P.]

Re: 68 Brake Proportioning Valve

i thihk you are refering to the pressure differintial switch---if it has an electrical connector on it---it is there to activate the "BRAKE" light in case of front/rear or even master cylinder leakage or other problems caused by uneven pressure in the hydraulic system

[Joe L.]

Re: 68 Brake Proportioning Valve

Kurt------

It is present on all 1968's. The same piece was also used for 1967. Other versions of it were used right through the end of C3 production. However, although it's widely regarded and referred to as such, it is NOT a proportioning valve and it has NO proportioning function. It is a brake fluid DISTRIBUTION block AND PRESSURE DIFFERENTIAL sensing switch. Those are its only 2 functions. The same functions were present in the several other switches used over the 69-77 period. For 1978+, the device added a proportioning function. However, it was a fixed, non-adjustable proportioning.