"Peening" on late production 69 axle codes

[bcmiller]

Gary, it’s for very late model year 69s as well. Did you read the date of that in my post?

There is no documentation that “peening is required”.  😀

[69Z28-RS]

Bryon,

That directive was for ALL Chevrolets (not only Camaros), and it corresponded to the normal 'date' for coming year changes (ie. For 1970, all Chevrolet model differentials got the C added).   

But what happened in parallel, was that '69 model Camaro production was 'extended' past the normal time, and the 'C' was NOT specified for '69 model differentials, and I believe that's why the C was peened out for late Camaro differentials.   Not surprising to me at all, as things happen in different locations at the same or similar times, and changes/corrections have to be made..   The peening over of the 'C' for '69 model Camaro diffs. was one of those things.

[bcmiller]

Gary. Wrong. They weren’t factory peened.

The axle plant didn’t change their policy or operations just because the model year was extended. Did you read Kurt’s earlier post? I am 99 percent certain there were modifications done after vehicle assembly.

You have your opinions and I have mine. Let’s leave it at that.

[ZLP955]

By 'factory' are you referring to the axle assembly plant, or the 2 Camaro assembly plants?

[69Z28-RS]

Gary. Wrong. They weren’t factory peened.

The axle plant didn’t change their policy or operations just because the model year was extended. Did you read Kurt’s earlier post? I am 99 percent certain there were modifications done after vehicle assembly.
...

Bryon,  I'm curious as to WHEN/WHERE you believe ALL the late '69 Camaro differentials had the inadvertent 'C' removed (or peened over)...  Or are you still contending that thousands of owners individually peened over the 'C'??

[KurtS]

In my mind, there's no question that the assembly plant peened the prefix C on these axles. I'm kind of baffled on why they thought they needed to though. It's also notable that it's not all late axles, just a subset. Wonder if it was just one supervisor....

[ZLP955]

In late '69 MY production (including the timeframe that peening has been observed), did the 'C' appear as a prefix to the axle code on Protect-o-Plates?

[cook_dw]

No Tim.

[bcmiller]

In my mind, there's no question that the assembly plant peened the prefix C on these axles. I'm kind of baffled on why they thought they needed to though. It's also notable that it's not all late axles, just a subset. Wonder if it was just one supervisor....

Why are they not all the same then? Why didn’t they use the same tool to do the task? Why was it ongoing intermittently for 2 months?

[cook_dw]

Why are all engine pad stamps not identical.?.  Why are screws left out of locations?  Why weren’t the same fonts and locations of stampings consistent throughout production.?.  Human error and it was over 50 years ago.  Although most things were pretty standard there are always anomalies..  This is just another one of those things that are not cut and dry.  I would like to see this thread continue with fact based posts but I guess that isn’t gonna happen.

[KurtS]

Why are they not all the same then? Why didn’t they use the same tool to do the task?

No one knows. Since it was not widespread and was not implemented on all axles, I would say it wasn't a high level edict. Therefore a procedure was not defined and documented. Leading to implementation that varied.
A good example of why GM liked and followed their procedures - consistency.

[69Z28-RS]

In my mind, there's no question that the assembly plant peened the prefix C on these axles. I'm kind of baffled on why they thought they needed to though. It's also notable that it's not all late axles, just a subset. Wonder if it was just one supervisor....

You guys have more data points/info that we readers do, but I've seen enough examples of 'consistent' peening to know that it had to be done in 'a' GM plant somewhere; probably NOT the axle plant, so that leave the assembly plant as the only possibility.  And unless I'm mistaken, all of the late '69 Camaros were assembled in the Norwood plant, so that narrows it down to be a 'time frame' inconsistency.  Do we have enough data to make an attempt to narrow in on the time frame when it was done?  Or was it so inconsistent that we have to deduce it was a particular supervisor on a particular shift that did it?   Can we expand the data listing we have by listing the VIN or date of the car the rear end came from?   That might give us some better 'timewise' information since rears were not used sequentially as the VINs themselves.

The ones I've seen here on this thread that appeared to have been 'peened' seemed to have been peened by multiple strikes by a blunt faced' small circular tool.  If there's examples of this peening which seem different than that, I'd love to see an example?

The service bulletin that Bryon posted doesn't really give us the dates for which the Axle plant received the information for changing the stamping of 1970 model year axles, but since they indicated the model year change for 1970 MY  the implication is that the dealers already had the information on 1969 axle stampings.'

I noticed that Corvettes were also on the list of Chevrolets which were to get the 'C' for '70 production.  I have an August built '69 Corvette that I could check on the stamping to see if it's 'AM'  or 'C AM' as the '70's were, but I don't recall ever hearing anything about a discrepancy on "Corvette axle stampings', but of course the assembly plant for Corvettes was St Louis.

[bertfam]

I noticed that Corvettes were also on the list of Chevrolets which were to get the 'C' for '70 production.  I have an August built '69 Corvette that I could check on the stamping to see if it's 'AM'  or 'C AM' as the '70's were, but I don't recall ever hearing anything about a discrepancy on "Corvette axle stampings', but of course the assembly plant for Corvettes was St Louis.

My October 21st, 1969 assembled L36/M20 Corvette has its original axle and it's dated 2 CAT 10 6 69 (October 6th, 1969, Heavy Duty 3.08 Posi assembled on the 2nd shift).

Ed

[69Z28-RS]

Ed,

Did you check the stamping on the differential in your Corvette?   Is it notated with the 'C' in front of the code?

[bertfam]

Did you check the stamping on the differential in your Corvette?   Is it notated with the 'C' in front of the code?

Yes I did and yes it is. And by the way, there's no mention of "peening" in the latest (5th edition) 1968-1969 Corvette Technical Information Manual and Judging Guide (TIM&JG). It only states “Those 1969 cars produced after September 1969 have 1970 differential codes.”

Ed