Is a 72 Cutlass Supreme power disc brake system supposed to have the proportioning valve included as standard from the factory? I have to replace the master cylinder and noticed it does not have the valve.( at least it is not near the M/C where you would expect it. I have driven the car enough previously and have not experienced anything unusual with the braking. I'm not even sure if it is the original vacuum booster M/C setup. Are the brake line threaded fittings standard size over a range of years? I'll have to take the cylinder in and match it up when I get a new one I guess. Thanks, Chumley

 

ALL disc brake systems have a proportioning valve. Starting in 1971, GM used a combination valve that incorporated the proportioning valve and the residual pressure valve into the distribution block. The combo valve should be bolted to the frame directly below the master cylinder.