Disc brake proportioning valve

[Terry69RSZ28]

Hi Everyone,
Do 69 disc brake proportioning valves have any numbers or date codes on them?
Thanks for your expertise, Terry

[69Z28-RS]

Yes, see photo...  I believe the date code is encoded as:   julian date - Yr .. (mine is '154 - 9')  for the 154th day of 1969...  Also  'K-H' for Kelsey Hayes  and an 'R' for ...??.. rear?

[BULLITT65]

great pic Gary. Now you just gave me something to want to look at next time I am in front of my own.....

[ZLP955]

Great article on brake valves right here: http://www.camaros.org/brakevalve.shtml

[Terry69RSZ28]

Thank you very much for clarifying my question!
Much appreciated, Terry

[69Z28-RS]

Absolutely ZLP...  JohnZ's article is great and I refer to it often myself.   (I should have remembered to refer to that in answering the OP's question)... 

[jdv69z]

So I have a question regarding the distribution block that turns the brake light on if there is a pressure differential between the 2 sides. Can this only occur when the brakes are applied? That is, can there be a pressure differential when the brake pedal is not being depressed? My brake light stays on whenever the distribution block wire is connected, and the ignition is on.. And I know that wire goes to ground. As if the internal spool which moves is permanently stuck somehow or touching gound?

[ZLP955]

Can't answer your question Jimmy, but if it turns out your switch needs a rebuild, here's a great tech procedure from Muscle Car Research: https://www.musclecarresearch.com/gm-3956727-rebuild

[jdv69z]

Thanks, I appreciate the info!!