1967 Brake Warning Light Switch - does it have a "heart-shaped" stamp on outer case?

[Scott S.]

This is a strange question, but I was examining the original dual reservoir brake master cylinder from the '67 L79 coupe last night, and looking at the Brake Warning Light Switch looking for dates. The switch is described in Noland Adam's book on page 388 and in the NCRS judging guide.

Two things caught my attention. The "date" on mine (if that's what it is) is "7 8 1", the same as "many" were found to be in Noland Adam's research. However, if that is indeed a Julian date code for 1967, 81st day, then it can't be original to the car, because if I understand correctly, the build date for the car is January 11, 1967. It has "F11" on the Trim Tag, and using the available Internet birthday calculators, I come up with the same date by searching the VIN.

Then I noticed that there is a heart-shaped "stamp" on the outer casing, facing outward toward the driver's side when mounted on the car. Does anyone else have this heart-shaped stamp on their Brake Warning Light Switch?

I have a suspicion about it, but I wanted to find out if anyone else has this mark, and what it might mean, before I jump to any conclusions.

Thank you,

Scott

[John H.]

Re: 1967 Brake Warning Light Switch - does it have a "heart-shaped" stamp on outer ca

Two things caught my attention. The "date" on mine (if that's what it is) is "7 8 1", the same as "many" were found to be in Noland Adam's research. Then I noticed that there is a heart-shaped "stamp" on the outer casing, facing outward toward the driver's side when mounted on the car. Does anyone else have this heart-shaped stamp on their Brake Warning Light Switch?

Scott -

My June-built '67 has the same markings - I'm sure the "2225781" is the casting number for the block.

[Scott S.]

Re: 1967 Brake Warning Light Switch - does it have a "heart-shaped" stamp on outer ca

Scott -

My June-built '67 has the same markings - I'm sure the "2225781" is the casting number for the block.

Thanks John, that means it's not an incorrect date part then :thumbs up:

When you said that yours has the same markings, does that include the heart-shaped stamp too (lower left-hand corner of the Brake Warning Light Switch, photo #1 and #4)???

[Edward J.]

Re: 1967 Brake Warning Light Switch - does it have a "heart-shaped" stamp on outer ca

Scott, I Thought The First Two Digits Or Three Were The Day And Last One Was The Year On Julian Codes?

[John H.]

Re: 1967 Brake Warning Light Switch - does it have a "heart-shaped" stamp on outer ca

When you said that yours has the same markings, does that include the heart-shaped stamp too (lower left-hand corner of the Brake Warning Light Switch, photo #1 and #4)???

Yes - mine's in a slightly different location, but it's there.

[Scott S.]

Re: 1967 Brake Warning Light Switch - does it have a "heart-shaped" stamp on outer ca

Yes - mine's in a slightly different location, but it's there.

Thanks again John. There goes my theory that it was a "stamp" that the previous owner might have used to "mark" his parts. My Dad bought this car in 1976 from Richard and Patricia Valentine, in or near Bradford, Ohio.

I thought maybe 'Valentine' = heart-shape mark.

I know, it was a long shot

[Scott S.]

Re: 1967 Brake Warning Light Switch - does it have a "heart-shaped" stamp on outer ca

Scott, I Thought The First Two Digits Or Three Were The Day And Last One Was The Year On Julian Codes?

Hi Edward,

I believe that's true in most cases. My clock once had (operative word being "had" ) what I believe was a Julian date code of "2 1 0 6", which should mean the 210th day of 1966 (see picture). In a slightly different format, the seat-belt tags have what might be called a Julian-style date of "50 E 66" for the 50th week of 1966.

But on some parts the year is listed first (6A1 = 1966, November, 1st week on Holley carburetor, not a Julian date, just an example), so it might be possible that some Julian date codes started with the year first too.

The reason for my original posting about "7 8 1" being a Julian date code is from what I read in Noland Adam's book, page 388, regarding the Brake System Warning Light Switch:

"The switch contained a manufacturing date code. According to the switch's original design blueprint, a date code representing the year and day were to be stamped on the side of the switch housing. However, examination of original examples have located the code on the center 'saddle' area. Typical codes are:

2 2 2 5
7 8 1

All switches we found had the '2225' code, but we have no idea what this signifies. We found several dates, with many '7 8 1' examples. 7 8 1 translates into 1967, 81st day, which is another way of saying Wednesday, March 22, 1967."


I didn't read anything about this specific part where the date code was called "Julian" in the Adams book, I must have added that myself, thinking it was a Julian-type code because of the 81 being called the '81st day' in the Noland Adams book.

I have learned that none of the reference books are always right 100% of the time, but between using three or four of them, I can usually get pretty close to an answer. If that doesn't work, I know that somebody HERE has the answer

[Edward J.]

Re: 1967 Brake Warning Light Switch - does it have a "heart-shaped" stamp on outer ca

Scott, I learned alittle more each day, thanks Ed

[Patrick T.]

Re: 1967 Brake Warning Light Switch - does it have a "heart-shaped" stamp on outer ca

While we're on this subject, does anyone have a see-though diagram of the inner workings of the '67 pressure differential switch? I would like to see how many working parts are inside. Mine is on the fritz right now and I have to take it off and try soaking the unit in some denatured alcohol, since it might be "gummed up" inside.

I do have a new repop switch, which isn't even close to my original. Would anyone know if I can swap out the new internals from this switch and install them in the original one? Thanks for any tips. PT

[Edward J.]

Re: 1967 Brake Warning Light Switch - does it have a "heart-shaped" stamp on outer ca

Pat, does the diff. pressure switch look like it will disasemable? I would think theres nothing to lose since it already does'nt work, there may just be a spring and piston and maybe a seal of some sort.

Are sure it inop. Ive seen the switchs fail that turn the light on.

[Patrick T.]

Re: 1967 Brake Warning Light Switch - does it have a "heart-shaped" stamp on outer ca

Pat, does the diff. pressure switch look like it will disasemable? I would think theres nothing to lose since it already does'nt work, there may just be a spring and piston and maybe a seal of some sort.

Are sure it inop. Ive seen the switchs fail that turn the light on.

Ed, my switch is exactly the same as Scott shows in the picture above. I have tested it and without a doubt it is in the switch. I will take it apart when I soak it in alcohol. As you said, I got nothing to lose. Or as a last resort, I can send it to Lone Star Caliper and let them rebuild it. Hopefully, it won't be a big deal to fix it myself. PT

[John H.]

Re: 1967 Brake Warning Light Switch - does it have a "heart-shaped" stamp on outer ca

While we're on this subject, does anyone have a see-though diagram of the inner workings of the '67 pressure differential switch? I would like to see how many working parts are inside.

Pat -

Photo below shows a later "combination valve", but the center section is the differential pressure switch, and shows how it operates; it's simply a spool, sealed on both ends, with a groove at the center. When there's a difference in pressure at either end relative to the other end, the spool shifts, and the switch terminal touches the taper on the groove in the spool, grounding the circuit for the warning lamp, illuminating the lamp. There is no valving function, nor is there any fluid flow through the spool - both ends are sealed.

[Edward J.]

Re: 1967 Brake Warning Light Switch - does it have a "heart-shaped" stamp on outer ca

Pat, I don''t know if the alcohol will help, the seal or seals may not like it, the seals may swell, maybe see if alittle air pressure will help once your ready to remove the pistons, rust is always a problem with cast iron.

[Patrick T.]

Re: 1967 Brake Warning Light Switch - does it have a "heart-shaped" stamp on outer ca

Thanks Ed, that was exactly what I was looking for.