1970 master cylinder question

[R N.]

Hello All,

In the 1970-72 Technical Information Manual it states the there is a date stamp along with a "TG" stamped on the front line area where it is machined on the master cylinder.

The way the manual is writting leaves me asking more questions about this stamping. Was the TG stamp and date stamps applicable to the 1970 M/C? or was that for the later '72 models?

What are the typical stampings that one would find on the 1970 M/C?

Also, what format was the date code?

Thank you for the help.

Regards,
Kurt N.

[Joe L.]

Re: 1970 master cylinder question

Kurt-----

1970 master cylinder for power brake cars was stamped "PG" on the "semi-circular" front machined area. This was also the case for 1971 models and some early 1972.

The julian date code is found on the front machined surface for the brake line. It will be a 4 digit stamping---the last digit of the year followed by the julian day of the year. For example, a cylinder manufactured on January 31, 1970 would be seen as "0031".

[R N.]

Re: 1970 master cylinder question

Thanks Joe...

Do you know anything about the TG stamp?

Regards,
Kurt

[Joe L.]

Re: 1970 master cylinder question

Kurt-----

I don't know that any were ever stamped "TG". I think that was a broadcast code used on some later 1972+ and was present only on the paper label on one of the bails.

[Harmon C.]

Re: 1970 master cylinder question

Kurt

The code was stamped on line boss with the date on all 73-77 corvettes and I would say it started after the code was not stamped on the front machined boss.
Lyle

[Dick W.]

Re: 1970 master cylinder question

On most cars you are unable to read the date code when the cylinder is installed, therefore it is not a judged item

[Harmon C.]

Re: 1970 master cylinder question

The boss is sometimes rusty and that makes it hard to read but if the area is clean the only problem is the size of the letters. In Bowtie judging I check it out but in flight judging it is one date that has not been judged. I would say it will be added or has been by some judges when the code and date are both stamped.
Lyle

[Terry M.]

Re: 1970 master cylinder question

On some of the earlier C3s the number stamped on the port area of the master cylinder makes no sense.

The original master cylinder on my January built 1970 has the single number 1 stamped there. Want to tell me what that means?

Even if you allow that the leading zeros are missing (like is done with the stamp on the AIR pumps), I doubt they were building master cylinders on the first of January 1970. And to confirm my suspicions I once saw a master cylinder for sale at a swap meet in the McLean County fair grounds with the same number 1 stamped on it. The entrepreneur selling it wanted $200 for this "extremely rare" (his term, not mine) example. Those of you who have been in the hobby for a while will know how long it has been since there was a Corvette swap meet at the McLean County fair grounds. Most used master cylinders were going for around $20 at that time.

That is the reason the earlier 1970-1972 TIM&JG did not specify any date information. Yes most are dated in an understandable fashion, but what are we to do with those which make no sense?

[Harmon C.]

Re: 1970 master cylinder question

Thanks for the information and I see why the date is not judged 70-72. The later master cylinders I have seen 73-77 all were dated correct with the code if original.