Master Cylinders: Drum vs. Disc vs. Power vs. Manual

[rich69rs]

Master cylinders have been discussed on several occasions on this forum in the past.  Often the discussion has been on the topic of residual pressure valves (check valves) located behind the tube seats in the outlet ports of the master cylinder body on cars with drum brakes and whether or not they should be there.  Some of those discussions can be found at the following links:

http://www.camaros.org/forum/index.php?topic=5189.0

http://www.camaros.org/forum/index.php?topic=3428.0

http://www.camaros.org/forum/index.php?topic=3657.0

http://www.camaros.org/forum/index.php?topic=3541.0

http://www.camaros.org/forum/index.php?topic=2938.0

http://www.camaros.org/forum/index.php?topic=3674.0

Recently, I acquired a copy of "BRAKES, standard, disk and power" which is a  training program booklet that was used by Chevy in their training programs.  The manual is #TP-53 and is dated 1969.

Attached to this post is a copy of the cover of the booklet.  My '69 RS has power drum brakes.  The master cylinder part number is 5460465 with a CT application code.  This past weekend I rebuilt my master cylinder with a rebuild kit that I obtained from NAPA.  The rebuild kit came with a new complete primary piston assembly, check valves and springs, and rubber cups for the secondary piston.  As you will see in the following postings - it is the critical dimensions of the secondary piston that establish the application code.

[rich69rs]

Second post showing the master cylinder for power drum brakes.  Originally from the factory, power drum brake master cylinders would have had check valves (residual pressure valves).

[rich69rs]

Third post - application code from my master cylinder

[rich69rs]

Fourth post - page 7 from the manual explaining the criticality of the dimensions of the secondary piston and the use of check valves for all drum brake applications.  Also, in the second column, it clearly states that all master cylinders mounted on an angle (power) would have bleeder valves - which my master cylinder does.

[rich69rs]

Fifth post - page 8 from the manual - continues the previous discussion and shows master cylinders for front disk / rea drum and master cylinder for 4 wheel disk brakes.

[rich69rs]

Sixth Post - Master cylinder from my car ready for reassembly.  Note that the secondary piston (which was re-used with new rubber caps) has a single groove on it denoting its application; i.e. CT code in this case.

Check valve and spring assemblies have already been installed with new seats pressed in place.

[rich69rs]

Seventh post - another view of front disk / rear drum master cylinder from the namual.

[JohnZ]

Nice thread - there are some pretty scary "conversions" out there that make it pretty obvious that some folks (including the outfits that sell the stuff) don't understand that brakes are an engineered system, or how they're supposed to work.