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Howard, thanks, I've printed that image for reference. For sure different than the later brakes.

Motors says Bendix had 4 types of brake systems in the prewar years. Hydraulics were Type 1: no eccentric, T-2: 1 eccentric, T-3: two eccentrics, and T-4 was all mechanical.

Prewar Packards from early 30s used mostly T-2 with T-4 used on some senior models. Postwar all used the type 1 which is on your 54 and what most of us are familiar with.

Motors did not mention any operating characteristics or advantages/disadvantages of one system over another and why one type in particular was chosen for use in a car but the shoe positioned eccentrics of T-2 and 3 must not have been that advantageous to be worth the added mfg cost since they eventually went away. Maybe there is someone who knows or is curious and enjoys doing research who could answer that.

Just for clarification, the post-war brakes had an eccentric, but it was located at the anchor pin area.

Kev: Here’s my speculation on that ‘extra’ spring. The force required to move the shoe that has the ‘extra’ spring would be greater than the other shoe. At constant hydraulic force that would equate to the shoe without the spring moving first . . . much like the modern system that has a primary and secondary spring set. My assumption would be the two upper springs are identical and the primary/secondary function is achieved with the ‘extra’ spring, a much more ‘Murphy’ proof design IMO.
dp

David, the interesting thing about that is on my '54 brakes, there is no "eccentric" spring, yet the two anchor pin springs are the same. Go figure!

Quote:

It appears all types have the usual upper anchor pin eccentric and that one is used for the upper end of both the primary and secondary shoes. From what I read the secondary shoe eccentric must be for mostly the bottom end or maybe a fine tuning adjustment -- but the instructions have it done first and then the anchor pin eccentric adjusted for clearance at the top of both shoes.

From the Motor's 17th Edition (for future reference):

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Howard, also, thanks for reminding me about the Motors and Glenn Manuals I had buried on my bookshelf. They always had better diagrams and explanations than the Packard manuals did.

Growing up in the '60s and working on a 1939, 1941 and several 1940 Packards, a 1946-1956 Motor's manual was all I had but rarely used it other than to get a specification and even those were often wrong, especially rod cap bolt torques as I discovered the hard way.

As for the side spring, my 1951 Henney-Packard has it but I can't recall if the passenger cars did or not.

Backing plates and drums painted with caliper paint. It took off the old paint with a rolock wheel and then cleaned everything with some thinner before painting. I'll let this cure for a couple of days while I wait for the missing parts from Kanter to arrive.

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