In the concern for safety, many decide to replace their original single chamber master cylinder for a duel system, but they want to keep their factory front and rear drums. (The duel chambers were required by federal law on all new vehicles about 1966.)
A current new duel chamber cylinder allows your front or rear brakes to operate if either half mal-functions. Before the new federal law, you only had the foot or hand pull parking brake to save you if you lost the hydraulic brake system.
If 50% of the brake system is lost in the new system you will still know it, but you can make it to a garage repair shop rather than a hospital or funeral home!
GOOD NEWS!
A NEW REPLACEMENT MASTER CYLINDER WITH NEW DUEL CHAMBERS IS AVAILABLE.
For Chevy / GMC ½ tons, an existing dual chamber master cylinder can now be used as a drum to drum replacement.
It is an excellent exchange for the original single chamber and it fits under the floor in the position designed by GM. No one will know you have made the safety upgrade.
The two brake line threaded holes on the same as the originals. The brake line holes are a slightly different diameter; however this kit easily makes the corrections with an adapter.
There is a new steel adapter that must be used to place the modified master cylinder in the correct position to line up as the original.
Another bonus! Because there are not disc brakes involved, there is no need for a proportioning valve to modify brake fluid pressure.
Jim Carter Truck Parts part numbers are HP415 for the cylinder and HP161 for the steel adapter.
Two Chamber Master Cylinder
Used with original brake pedal and includes rod from cylinder to pedal and mounting hardware.