C3 Master Cylinder date code

[Jon S.]

I have an oddball master cylinder on my '69. It is a 509 casting (manual brakes), but has the 'PG' stamp (power brakes). The car has power brakes, so I am trying to find a 546 casting for it. The problem is that mine also has no date code.

The TIM&JG says that the date code should be stamped on the front line fitting surface, but does not say if it is a julian date, month/day/year combo, etc. Since mine doesn't have a code on it, I do not know what to look for. Can anyone tell me what the format of that date code should be? Car is an August '69 build.

Thanks,
Jon
#10673

[Roger S.]

Re: C3 Master Cylinder date code

On my '73 the code is 3171TG. 3 = 1973, 171 = June 20 (Julian code) and the TG is for power brakes.
Roger

[Jack H.]

Re: C3 Master Cylinder date code

Date coding of master cylinders seems to be a hit/miss proposition with some having no sequence at all. Appears the practice varies with the model year of the car because some Shark JG books detail the sequence, others don't and it's often mentioned there may be no coding at all.

Those JG's that define the dating sequence give an example like this "YCXYYY" where YC is the PB broadcast code, X is a single year digit, and YYY is the Julian date of that year. When you do find an original dated MC, the code is stamped in a circular pattern on the machined boss serving the forward brake line in VERY small font.

[Terry M.]

Re: C3 Master Cylinder date code

The reason the 1970-72 manual does not give the code, and I think the 1968-69 is the same, is just what Jack cites. Not only is it hit or miss, but some of the codes make no sense at all.

I know of one original to the car 1970 master cylinder that has the single number 1 in the date code place. Lest you think this unit is an anomaly I did once see a master cylinder with the same code for sale at a large swap meet in central Illinois. It was billed as a real rare item.... $300 for just the bare master cylinder. The vendor and I had a discussion, which I will not bore you with.

I will share with you that he had no more idea what that code meant than I did, or do. About the only thing we agreed on is that it is not likely that these units were assembled on January 1. On the other hand, we both could be wrong. January 1, would work as a date for the car it is on, but I doubt too many judges would believe it was assembled on that date ..... I don't.

[Rich G.]

Re: C3 Master Cylinder date code

Terry

On 68, did they ever use an alpha-numeric code, like 8 A 5 for January 5, 1968?

Rich Giannotti

[Terry M.]

Re: C3 Master Cylinder date code

I don't know Rich because I rarely look at the date code when judging the master cylinder. I generally don't want to get bogged down with codes I can't understand when the goal is to judge the entire engine compartment. Also the code is often not visible.
No one has ever brought that style of master cylinder code to my attention, but posting it here may get someone else's attention.

[Rich G.]

Re: C3 Master Cylinder date code

Thanks Terry.

I have a PB MC I got at a swap meet. The P/N is 5480346 which the 68 TM&JG says is the power brake MC for 68. It has the "PG" stamp. It also has a stamp on the outboard side (the p/n is on the inboard side) that says 8 D 5. The characters are about the same size as the p/n characters. The p/n characters are raised, the "8 D 5" is stamped. There is nothing I can see where the JG says there should be a date code.

I had it rebuilt and am using it in my 68 as the one that was in there when I got it was a generic replacement.

Rich Giannotti

[Terry M.]

Re: C3 Master Cylinder date code

Rich, where is that code stamped? That sounds like the traditional casting date configuration. When present casting dates are usually cast into the item.

Master cylinder date codes are usually stamped on the machined surface above the front of the two brake line nuts. It is usually stamped in very small numerals, and is a Julian date (1 = Jan1, 2=Jan2 and so on) and a single number for the year. I have forgotten if the year is first or last, but there was a story about it in The Restorer by Hans Norberg.

[Rich G.]

Re: C3 Master Cylinder date code

Terry

Thanks. I'll look closer, but I don't see anything on the machined surface. I assume you mean in the area where the front brake line exits and there is a bleeder above that.

The area around the brake line fitting is machined, but I can't see anything there. I should have looked closer before I installed it.

Not a big deal, I just get curious when topics related to what I have come up. Always trying to learn something.

Rich Giannotti

[Terry M.]

Re: C3 Master Cylinder date code

"I assume you mean in the area where the front brake line exits and there is a bleeder above that."

Yes Rich that is the correct location. As Jack said they are not always stamped, and as I noted sometimes the stamp makes no sense. I'm sure there is something going on there; we just don't know all the answers.

[Harmon C.]

Re: C3 Master Cylinder date code

I check the date code on 73-77 bowtie judging and I feel they were all dated except those made the day before a holiday or friday afternoon when going home was more important than a date and in the middle of the pallet the inspector will never know. It may be rusted or painted over but I have found the stamp on many cars that the owner could not see as it is small. Lyler