79 Brakes

[Michael79]

Can anyone tell me why does the '79 proportioning valve block have two outlets for the front brakes and one for the rear. Is it to cut down on the need for an additional block or is there another reason?
I ask because I am about to install a line lock which necessitates the need to blank off one of the front line outlets on the proportioning block, run the other oulet through the line lock solenoid valve then from there into a new T piece which distibutes to the front calipers.
Would blocking off one of the outlets affect the working of the proportioning valve?
Michael

 

[brusso]

I believe the reason for one outlet to the rear was for economic reasons. One is it is cheaper to run one larger (1/4") line to a block/ flex line, then a smaller (3/16") crossover to the other rear flex line. Same for the front. It is more practical to run steel line to each front corner flex line. As opposed to having the same arangement as the rear. Also that combination valve casting is the same that GM has used since GM has been using them. As far as blocking one of the front outlets? That block has two anti-locking valves. One for the rear and one for the front. Think of the two outlets for the front as an elaborate T block. If one side fails, they both fail. (hydraulic theory) I hope this helps.