1968 disc brake proportioning valve big nut

[john302]

What is the correct plating on the proportioning valve big nut ?It is for my Dec.67 built 68z. I always thought silver zinc was correct,but the one I just took apart is gray phosphate. Has anyone else seen this before?  Thanks John

[JohnZ]

Photo below is my '69 - the master cylinder and booster have been restored, but the metering valve is original and has never been touched.

[sd1968z28]

i think my 68z built  in april it was  plain cast color.

[Jerry@CHP]

67 and 68 nuts were not plated silver cad like the '69s.  The '69 nuts are also larger in dia.

Jerry

[john302]

Is gray phosphate the correct plating?

[68Zproject]

Mine was just bare metal, but who knows what it looked like when it left the factory.

[Pex68]

Here's some pic's of a NOS one.  The plating is more of a tin-zinc that's not been buffed or tumbled.

[Jerry@CHP]

They were not plated in '67 and '68.

Jerry