Brake question

[pontiacgp]

yes this is correct.

i was taught this in tech school, but this usually pertains to masters mounted at a level even with or below the wheel cylinders, like '57 olds that is mounted under the floor, not in masters that are mounted high on the firewall like our gbodies. i can find no factory diagrams indicating this is on our gbody master cylinders. between the weight of the fluid and the internal spring/cup assembly of the wheel cylinders, it would be superfluous.
joe

I did some checking and they used to run the residual valves in the master that were installed in the same position as the ones in G bodies but they stopped installing them so I have been wrong thinking that our brake system had residual valves. When we changed the master in our G body circle track car we ran a manual Chryco box with an inline 3 lbs residual valve for the front disk and 10 lbs for the rear drum. I didn't think that spring in the cylinder held the shoes in place but one day I will remove the brake line to one of my back wheel to see what happens.

 

[BOXCARS]

here is my experience with disc brake upgrades I've made over the years.
i started with converting my fronts to '96 corvette hd rotors and calipers. no other changes. rear brakes would lock up prematurely.

many years later, upgraded rears to ls1 camaro rear disc rotors and calipers. no other changes made. rear brakes worked properly, no premature lock up during panic stops, but i didn't drive this very hard before i performed the next mod.

upgraded front brakes to 2000 corvette 12.8" rotors and calipers. this caused me the most frustration. pedal feel was weak, long pedal travel, like i had air in the system. i would run out of pedal reserve. not a happy feel.
switched master cylinder from factory 79 cutlass to a master for an '87 monte. pedal feel got better but still didn't feel right. switched master to a mid '70s corvette master, sorry i don't remember if its a 1" or 1-1/16" bore. pedal feel is now normal.

as far as the proportioning valve is concerned. i have not changed it. i have safely tested the fore/aft balance for street driving, no premature lock up was experienced, wet or dry.
also, these valves do not have a residual pressure valve inside them. contrary to what you might read, they don't. i can not find any factory diagrams (gm, kelsey-hayes, bendix) indicating such for a valve in the gbody. as further evidence, if you look up rear wheel cylinder o-haul kits, they show a spring and cup assembly to keep the rubber cup lips in contact with the wheel cylinder bore.

i have been quite satisfied with this arrangement. 3000plus miles including 1000 miles towing another cutlass from alabama to minnesota. oh yea, and this was in the rain. think of a 3000lb trailer with no trailer brakes. my brakes performed flawlessly.

***results may vary***

joe

When I changed over to LS1 brakes on my 87 GN & 86 El camino, I installed B-body master cylinders on both. This has afforded me a great brake pedal right from the beginning. The B-body unit has a slightly larger reservoir and bore. Like you, I never touched my proportioning valve, though I have read some who have converted to LS1 brakes recommended the installation of an adjustable proportioning valve.