67 509 master cylinder

[Rob A.]

I have a 509 master cylinder. The"DC" letters stamped on the front are recessed. I need to know if this is an original or not. I have a picture of an original, which corresponds to the judging manual, with "raised" DC letters. Should I assume this was not original, but stamped to look like one?

[John H.]

Re: 67 509 master cylinder

Rob -

The "DC" letters are STAMPED on the machined surface, not raised casting numbers - the lighting in the photo you refer to must make them appear to be raised. The 509 you describe is correct for a '67.

[Rob A.]

Re: 67 509 master cylinder

I also see a stamp 9258 on the area where the front line attaches. I believe this is the 258th day of 69. If this is correct, then I assume it is not an original '67 509 master cylinder.

[Rob A.]

Re: 67 509 master cylinder

I see now from a better picture that the DC stamp is not raised. Does the #9253 on the flat of the front line connection mean this is not an original '67 509?

[John H.]

Re: 67 509 master cylinder

The 509 casting with the "DC" stamp was also used as a service part; it was catalogued as an active replacement part (#5458833, note...stamped "DC") for all '67-'73 Corvettes (except J56) as late as August, 1973, and probably later. The '67 production part carried P/N 5458831; the service part was identical, but probably carried a different part number due to the way it was packaged or because it didn't have a "YA" broadcast code label on one of the cap bails.

[John H.]

Re: 67 509 master cylinder

See my post below - it appears to be a service part, made in mid-September 1969. My 509 has no julian numbers stamped on the machined surface around either of the ports.

[Joe L.]

Re: 67 509 master cylinder

Rob-----

The "9253" stamping on the front brake line connection machined surface is a manufacturing date. It decodes to the 253rd day of 1969. So, this master cylinder was either an original one off of a 1969 or 1970 Corvette or it was a SERVICE replacement part made on that day. There's no way to tell which and it doesn't matter, anyway.

The '509' master cylinder was used after 1967 in PRODUCTION and SERVICE. For 1968+ it was used for Corvettes with manual brakes. It was not used after 1967 for any Corvettes with power brakes, although it was used for BOTH manual and J-50 power brake 1967 Corvettes.

Except for the practically indiscernable date code found in the area that you described, there is absolutely NO difference between a 1967 "509", "DC"-coded master cylinder and any 68-73 "509", "DC"-coded master cylinder.

[Craig S.]

Re: 67 509 master cylinder

My original 67 509 DC cylinder has no Julian dates either, apparently the production units did not carry a stamping like the service dated items....Craig

[William O.]

Re: 67 509 master cylinder

Look at your casting number not all "509" were 67'
Casting number 5455509 with a "DC" stamp on the front machined area were used for 1967 "standard" or J50 power brake cars.

[Joe L.]

Re: 67 509 master cylinder

Craig-----

No, the date stamping was not unique to SERVICE master cylinders. My guaranteed original, 1969 PRODUCTION "509" master cylinder has the julian date code. I don't know if the dates were being stamped on 1967 master cylinders, PRODICTION or SERVICE. I think that the practice started after 1967.

[Craig S.]

Re: 67 509 master cylinder

Thx Joe!