Date codes and other info for some, not all, BT trans cases

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Re: Date codes and other info for some, not all, BT trans cases

#16

Post by panhead » Fri Jun 10, 2016 10:11 am

Thank you for sharing!



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Re: Date codes and other info for some, not all, BT trans cases

#17

Post by 1950Panhead » Fri Jun 10, 2016 1:38 pm

Eric,
This is excellent work, thanks for posting.

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Re: Date codes and other info for some, not all, BT trans cases

#18

Post by Bigincher » Fri Jun 10, 2016 5:05 pm

Eric, it's really good to see some of your knowledge published in a complete and comprehensive form like this. It's an invaluable resource, and I hope will be a chapter or series of chapters in a book that I hope you're able to produce at some point. Engine cases, cylinders, cylinder heads, transmissions, steering forks, frames, wheels, and more- when it comes to identifying stamps, codes, and characteristics, you're the man!
Thank you for the above information, and best of luck in any future endeavor. (Seriously- you should print a book!)

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Re: Date codes and other info for some, not all, BT trans cases

#19

Post by Speeding Big Twin » Sat Jun 11, 2016 10:12 am

Cheers, guys, and thanks for the kind words. I don’t think I’ll be going to print anytime soon though. There are still a few codes and other things I’d like to resolve in one area or another.
Eric

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Re: Date codes and other info for some, not all, BT trans cases

#20

Post by George Greer » Sun Jun 12, 2016 6:55 am

Speeding Big Twin wrote:Next code looks like I 9 and it appears to indicate September 49 as opposed to September 39.

P17A.jpg

P17B.jpg

P17C.jpg

I also have other examples that appear to be I 9 on 1949 cases and it is something I am still looking into. On a 121 35 case, M9 has yet to be seen by me so if you have an example then please let me know. L 9 is the latest I have for 1949 so far but regardless of which letter(s) indicated Dec 49, I do not know if letter-number was the only format used for BT trans cases that month. For BT aluminium engine parts cast in Dec 49 I have seen two code formats: letter-number; and numbers-only. These suggest Dec 49 was a changeover period for engine code formats so a similar thing may have happened with date codes on BT aluminium transmission parts.
Eric

Eric,

Great information here, and I will buy the book too!

I built a transmission using that case.

It is now on its way to Portland Oregon where I will install it into my project bike.

I have a few other photos if you need them.

George

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Re: Date codes and other info for some, not all, BT trans cases

#21

Post by Speeding Big Twin » Mon Jun 13, 2016 3:51 am

Thanks, George. Good to hear your bike is progressing. I’m okay for photos of that one at the moment. I have a couple more examples of I 9 cases with the beefier bosses and over the years I tried interpreting the code in other ways for those particular examples but none of them worked and I kept coming back to I 9 for Sept 49. It will be interesting to see if M9 shows up on a BT trans case and I’m also looking for what happened in Dec 59.
Eric

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Re: Date codes and other info for some, not all, BT trans cases

#22

Post by Panacea » Tue Jun 14, 2016 5:04 am

Interesting stuff Thanks for posting...Mikw

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Re: Date codes and other info for some, not all, BT trans cases

#23

Post by Panacea » Thu Jun 16, 2016 4:47 am

Here's another example from 43?
IMG_1096.JPG
IMG_1096.JPG (35.91 KiB) Viewed 4279 times

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Re: Date codes and other info for some, not all, BT trans cases

#24

Post by hplhd » Thu Jun 16, 2016 6:30 am

thanks eric.

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Re: Date codes and other info for some, not all, BT trans cases

#25

Post by Speeding Big Twin » Thu Jun 16, 2016 11:34 am

Mike, yes, that would be 1943, August. The insert may be bronze if original.


Cheers, Rich.
Eric

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Re: Date codes and other info for some, not all, BT trans cases

#26

Post by 58flh » Sat Jun 18, 2016 11:48 am

Eric----Your knowledge is priceless!//I have been able to CORRECTLY identify MONTH for 3 of my customers using your wealth of knowledge!.We knew the years/but when it came down to the bosses//I was at a loss for info!.Thank-you SOOO MUCH for sharing your Years works of Coding knowledge!----Respectfully---Richie///(oh I to would purchase a Book if you ever get around to Doing so!).

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Re: Date codes and other info for some, not all, BT trans cases

#27

Post by Speeding Big Twin » Mon Jun 20, 2016 5:19 am

Cheers, Richie. Re the two lower bosses, on CAI in Feb 2011 Matthew Olsen mentioned the change. He said more material was added there as of sometime in the early-50s. I began looking into it and tracking the difference via the date codes. Matthew was close with his estimation but in fact it seems the change to the casting occurred at some point during the 49 calendar year.
Eric

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Re: Date codes and other info for some, not all, BT trans cases

#28

Post by VPH-D » Thu Apr 27, 2017 6:30 pm

I had a look at the trans for my 45FL last week. It has an L4 date code, with a steel insert for the mounting bolt.
VPH-D

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Re: Date codes and other info for some, not all, BT trans cases

#29

Post by Speeding Big Twin » Sun Apr 30, 2017 2:31 pm

Thanks VPH-D. Steel insert as original is consistent with L 4.
Eric

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Re: Date codes and other info for some, not all, BT trans cases

#30

Post by Speeding Big Twin » Sun Apr 30, 2017 2:34 pm

Two DCs that can be added to the list in my first post are from December 1939 and June 1949. The first case below has rounded bosses at top left so in this instance L 9 indicates Dec 39. Also notice the insert.
December 1939 case.jpg
December 1939 case.jpg (96.15 KiB) Viewed 2940 times
December 1939.jpg
December 1939.jpg (99.57 KiB) Viewed 2940 times
On the next case F 9 indicates June 49. When I started this thread I had photos of what appeared to be a June 1949 case but the DC wasn’t clear. The F 9 example below is much better and the case has beefed up bosses for the left-side mounting studs. June 49 is now the earliest casting I’m aware of that has the beefier bosses.
Eric
June 1949.jpg
June 1949.jpg (109.49 KiB) Viewed 2940 times
June 1949 case.jpg
June 1949 case.jpg (85.71 KiB) Viewed 2940 times

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