Anyone know how to decipher the date codes on a 240Z caliper. Have seen lots of numbers on both sides but not sure what they mean.

I have the same question. 

Bump. Anyone ever figure this out?

Anyone have the Rosetta stone for the date code on the Sumitomo calipers?

Sorry can not help with date coding.  But here are pictures of my newly rebuilt calipers.     Build date 8/72

Rebuilt by PMB Performance thanks to @conedodger  for his recomendation.

4   2   M                                                                                                    4   2   H

     31                                                                                                             35

         4   2    A                                                                                        4   2    1

            (4?)1                                                                                              46

Eric the owner of PMB is on his way to his class reunion in Michigan. One of the kids is driving while he rehearses with his Strat in the back of his Cayenne. 
But he thanks you @SteveE! 
 

yes, he is the entertainment. Once every decade or so, his old band Brat gets back together for a gig. They opened for Heart a few times in the 1980’s. They make some good noise! 

Edited August 23, 2024Aug 23 by conedodger

Thanks Steve. After looking at some calipers and seeing your pics, here's my read:

It seems pretty clear that the number in the center is the year. And since the right position can have both letters and numbers there are 36 choices, I'm guessing that is day of the year. Making the left position the month.

Some supporting pics. This caliper came from a 78. Date code "1 8 R" :

And these came from a mid-1970 build. Codes "3 0 B" and "3 0 Z"  :

And on my 77, I didn't pull a wheel and take a pic, but I've got a  "3 7 K"

  On 8/23/2024 at 1:13 PM, Captain Obvious said:

Thanks Steve. After looking at some calipers and seeing your pics, here's my read:

It seems pretty clear that the number in the center is the year. And since the right position can have both letters and numbers there are 36 choices, I'm guessing that is day of the year. Making the left position the month.

 

Works for me, my calipers are coded 9 0 2.

Both sides apppear to be date coded on mine and they are different.  Does that make sense?

  On 8/23/2024 at 6:12 PM, SteveE said:

Both sides apppear to be date coded on mine and they are different.  Does that make sense?

I just checked back into my project pics, have a shot of one backside and it is 7 0 X. No surprise to me as front and rear casting runs at a factory could have different schedules.

Thanks for checking.....and making me feel better😄

Yes, it totally makes sense  that the date codes on front and rear halves could be different. I would expect them to be "in the same ballpark", but certainly don't have to be identical.

I would also consider it completely reasonable to see some cars with a build date early in a year to have calipers with a year code from the previous year. For example, something built in Feb 1971 might have a "0" caliper on it. Something from October-December 1970 maybe?

@SpeedRoo and @inline6, Does the suggested decode breakdown comply with what you have in your possession?