1966 BB Coupe M22?

[Michael H.]

Re: 1966 BB Coupe M22?

This may not be accurate but... wasn't the M-22 only available for a short time in the beginning of 66 production? Does Noland's book mention anything about the ECL continuing throughout the 66 model year or was it dropped early in prod?

Does the 66 AIM show that it was dropped? I don't have access to my AIM so I can't look it up.

[Warren F.]

Re: Here's to a Good Whine in Your Future!

Just think, a total of 389 M22's for 7 model years in the Corvettes history!!!!!!!!!!!!!!!!!!

[Jack H.]

Back...

from an extended weekend of swap meet stalking and dug out my records. NOPE, I sit corrected! The paper label affixed to the top of the pumpkins was simply a repeat of the broadcast code eventually wacked into the bottom side. So, Joe's 100% correct, the only ID marks on rear ends were the broadcast code and NOT the ECL code.

So, for the purposes of forensic identification as to whether the original post car in question could have been BB + M22, the broadcast code of the rear end isn't detailed enough to distinguish between BB and M22 vs. BB and M20/M21...

[Jack H.]

Re: 1966 BB Coupe M22?

Noland's book states the ECL classification for positraction underwent five discrete revisions after its initial release for '66 (six tables in total) with the meaning of each ECL code changing slightly from revision to revision. ALL of the revisions provided M22 product offerings. There is no mention under the M22 option section of it having been restricted or discontinued during the '66 model year.

[Michael H.]

Re: 1966 BB Coupe M22?

Thanks Jack, I vaguely remember the large number of ECL's in Nolands book but I don't remember any details. My original AIM shows the M-22 option being first released in, I believe, October of 65, and then dropped in late November. I don't know if this change or notation is in the reproduction AIM manuals but it's shown in the original manual that I have. There are a lot of differences between an original and a repro copy. I didn't see any info that would indicate the M-22 coming back into production after the November cancellation but it certainly is possible that it did happen. I'll try to dig out more info.

[Art A.]

Re: Back...

Jack, The ECL was never "attached" to the vehicle in any manner---period! If Noland inferred that he was missed guided. As Michael has stated the REPRO AIMs everyone uses are INCOMPLETE and should not be used as gospel.

JMHO
Art

[Art A.]

Re: 1966 BB Coupe M22?

Jack, Before I comment further, could you please clarify some of your post:

" Noland's book states the ECL classification for positraction underwent five discrete revisions after its initial release for '66 (six tables in total) with the meaning of each ECL code changing slightly from revision to revision. ALL of the revisions provided M22 product offerings. There is no mention under the M22 option section of it having been restricted or discontinued during the '66 model year. ", as I don't want to misquote you.

Are you saying that Noland's book states the ECL Classification for positraction underwent five discrere revisions------(in the AIM?)-----after its initial release-----(again, in the AIM?)------for '66 ( six tables in total)------(What tables?)------with the meaning of each ECL code changing slightly from revision to revision------(I don't understand, are you/Noland talking about the AIM revisions?). There is no mention under the M22 option section of it having been restricted or discontinued during the '66 model year. -----(I also don't understand this statement, are you talking about Nolan's book or the M22 option section of the AIM?)
Jack, I'm not trying to be a smartass here, nor am I trying to be difficult, I'm just trying to help clarify the Chevrolet system so MAYBE there won't be so much misunderstanding about things such as this.

Respectfully

Art

[Jack H.]

Re: 1966 BB Coupe M22?

I take it you don't have a copy of Noland's book to reference, Art... Well, in the '66 section on G81 Positraction Rear Axle, Noland denotes the special wire-on ID tag used on M22 only equipped cars (PN 3892548), then publishes six tables of ECL codes for the rear end.

The first is a complete list of ECL codes with gear ratio and usage data (defines the upstream transmission in the car + the engine) which Noland says was effective from the start of production to 10/23/65. The second table he calls 'Revision 1' and it's also a complete list of ECL codes in the same layout as the first table which he says was valid from 10/23/65 to 11/11/65.

Next, comes his 'Revision 2' ECL table where only two codes are listed and Noland says these codes (XA and YA) were added to the overall table effective 11/11/65 through 11/23/65. This is followed by a 'Revision 3' table stating the usage definition of four existing ECL codes (JA, KA, DA, and LA) were changed effective 11/23/65 to 1/10/66.

His 'Revision 4' table states ECL code BA underwent a usage definition change (not available with M35) effective 1/10/66 through 6/29/66. And finally, his 'Revision 5' table restates all of the ECL codes and Noland claims this table was effective from 6/29/66 to the end of the '66 production year.

The above tables are then followed with a summary table listing each ECL code, the rear end ratio applicable and the qty of units built during the '66 model year. Two paragraphs of text follow the table and that's ALL Noland recites on the subject:

"As seen above, the Positraction limited-slip rear axle was a popular option on 1966 Corvettes. In order to maximize performance, engineers sought the best combination of transmissin and rear end gear ratios. This was especially true for the new L36 and L72 427 CID engines. There were many changes to G81 during the 1966 production year.

Production quantities are not given in relation to the ECL lists above because the restrictions changed so often. Also note the ECL QA, listed as a production quantity of 86, is not shown in the ECL usage lists at all. It is described in the production figures list as 'used only with M21, 86 units, 4.56 ratio.'

Note there is no reference in Noland's text to the AIM. What I was saying was the ECL list defines the rear axle in relation to BOTH the specific transmission and the engine with discrete codes for M22 used with L36/L72 engine configurations. However the rear axle codes stamped on the housing (and applied via paper stick-on label) are NOT ECL codes and they lose definition since those codes only define rear end ratio, posi vs. non-posi, and gross engine configuration (SB vs. BB).

Hence, as others said, there was no use of ECL codes on the car itself or its parts with only the 'broadcast' code reflected on the rear axle. Since the broadcast code fails to be as specific as the ECL code (rear axle ratio, upstream transmission specifics, and upstream engine specifics), my suggestion that the poster of this thread seeking proof his car was originally a rare M22/BB might be able to actually document that without having the factory original paperwork doesn't work.

I was WRONG. I thought the paper label affixed to the top of the 'pumpkin' that few know about vs. the code stamped in the bottom of the carrier was the actual ECL code. Joe Lucia challenged me and I went through my files of pictures of untouched rear ends dropped from cars that still had readable paper code tags on them. Yep, EXACTLY as Joe had said, the codes on those paper tags WERE the broadcast code and NOT the ECL code.

So, I returned to the DB and posted a 'mea culpa' retraction. Now, that was a lot of typing, so tell me if there's anything else I need to disclose, Art...

[Art A.]

Re: 1966 BB Coupe M22?

If by "Noland's book" you are referring to Corvette Restoration and Technical Guide volumnes 1 & 2, you are right Jack, I don't have a copy of Noland's book-----I have TWO, one given to me by the AQ president(leather bound)and one given to me by Noland (With a hand written letter of thanks for my technical help in their research on said book)---but I guess you wouldn't know that. So, I guess I will bow to your knowledge on this subject. End of discussion.

A man convinced against his will is a man of the same opinion still.(Dale Carnegie)

Art

[Bill Farmer]

Re: 1966 BB Coupe M22?

Hey everyone, the tranny is out of my car and....... it is not an M22. It was apparently drilled later on. Thanks for all the help. Bill