Author Topic: New to this site!  (Read 3981 times)

william

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Re: New to this site!
« Reply #15 on: September 26, 2017, 08:29:35 PM »
I have been working on 'reverse-engineered' 1969 production schedules for many years. Data used to compile this includes:

•   Chevrolet 'last car of the month' data for both plants
•   Known production rates of 57 cars/hour at Norwood late Sept ’68 through 1st week April 1969
•   Print dates on Van Nuys body & chassis broadcast copies. 
•   A very few factory to dealer invoices

Each of these sources requires interpolation.

The ’last car of the month’ VIN was recorded at the end of the 2nd shift on the last financial day of the month. It wasn’t always the last calendar day of the month. The successful completion of roll-test marked the car as complete. However, cars were not final-assembled in VIN order. The next car through roll-test could have an earlier VIN; on occasion several hundred units earlier.

People that worked at Norwood are emphatic about the production rate of 57 units per hour. It’s a simple calculation but requires knowing how many work days there were. Did they work only 1 shift on Christmas Eve? Did they work the day after Thanksgiving? For the most part it works out but on occasion requires making assumptions about overtime or shutdowns. It works for January ’69 if I assume production started on 2nd shift January 2nd and they worked a full Saturday the following week.

All bets are off after Firebird production moved to Norwood mid-April. They probably still built 57 units per hour; how they were allocated is not known.

It’s been stated many times but bears repeating: Body & Chassis Broadcast Copies were generated by Chevrolet Assembly after the completed body was received into the body bank. The date on them is when they were printed. Typically the date is a calendar day or two prior to completion.

Factory invoices are rare. The CRG was fortunate to locate almost 200 dealer copies from Norwood for the 1969 model year. There are two key dates on them:

•   Date shipped
•   Date of execution

The invoice from ZL1 #1 has been around for years. It’s known ZL1s #1 N569358 & #2 N569359 were delivered on Christmas Eve, 1968 from a 1989 interview with Fred Gibb. The date shipped on the #1 invoice is 12/30/1968, date of execution 01/09/1969. The date of execution is obviously irrelevant. In this case the cars were expedited, shipped soon after coming off the line. But in comparing almost 200 data points from the invoices to a production calendar, only 11% shipped the same day they were completed. 34% shipped the next day; 12% shipped 2 days later. That means 43% shipped 3 days or more after production; a few waited 11-12 days.

Conclusion: The “GM Official Production Date” on the NCRS report is from GMAC shipping info and is likely the date shipped. The actual production may be the same date but most likely is not.

I expect that some internal paper document for each VIN was time/date-stamped as the unit completed roll-test. However that data was not relevant outside the plant so there was no need to disseminate it. I believe dealers received reports on assembly scheduling, if not actual production. There are internal Yenko Chev docs around with columns titled ‘body build date’ ‘body comp date’ and ‘ship date’. Some are filled in; many are not. But the dates appear to be estimates; they show N578878 shipping February 7th when it could not possibly have been built by that time. Other close VINs shipped February 20th.

The production schedules will always be a work in process as more data is acquired. Lately, I only occasionally have to make adjustments it so it must be getting close.


« Last Edit: October 10, 2017, 07:41:30 PM by KurtS »

BULLITT65

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Re: New to this site!
« Reply #16 on: September 26, 2017, 08:55:59 PM »
Thank you for putting the time into this, and one better explaining it to us.
1969 garnet red Z/28 46k mile unrestored X77
-Looking for 3192477 (front) spiral shocks 3192851 (rear)
-Looking for an original LOF soft ray windshield
-Looking for original Delco side post negative battery cable part # 6297651AV

Rich 5150 69

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Re: New to this site!
« Reply #17 on: September 26, 2017, 11:47:10 PM »
Wow William, did not know it was that involved, great writeup...Thanks..!

Petes L48

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Re: New to this site!
« Reply #18 on: September 27, 2017, 12:34:05 AM »
Many thanks for such a detailed reply and your tireless research,William.

KurtS

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Re: New to this site!
« Reply #19 on: October 11, 2017, 02:45:49 AM »
However, cars were not final-assembled in VIN order. The next car through roll-test could have an earlier VIN; on occasion several hundred units earlier.
This change in order occurred in the Body Bank. IMO, it's unlikely that VIN's were out of order by that much, because they were always pulling from all 6 lines in the bank.
Kurt S
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69Z28-RS

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Re: New to this site!
« Reply #20 on: October 11, 2017, 03:04:28 AM »
YIPPEE!!!!    :)   

... sorry..  just happy to again be reading CRG posts...  :)
Gary W / 09C 69Z28-RS, 72 B 720 cowl console rosewood tint
69 Corvette convertible, silver/black 350 hp,
60 Corvette white/red, 72 Corvette coupe, '70 Mach I 
90 ZR1 red/red #246, 90 ZR1 white/gray #2466
72 El Camino, '55-'56-'57 Nomads, '55-'57 B/A Sedan

william

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Re: New to this site!
« Reply #21 on: October 12, 2017, 10:07:44 PM »
None of us was there, so when I started working on this I asked someone who was-John Z:

Yes, a body could be held (only in the Body Bank) for a full shift, and a sharp bank supervisor was always prepared to do that if he had to; however, the body was VIN'd  before it was released into the bank, so it was possible to see some pretty significant VIN offsets -vs. actual physical line position. With a nicely-balanced schedule, up to a six-unit difference wouldn't be unusual, and ten or twelve tells you that there had been excitement of some sort up in the Body Bank.

This is important because the last VIN of the month is the basis for reverse-engineering the calendar. If it so happened that the car selected as last VIN of the month happened to be significantly out of sequence, it messes up the calendar. It is possible that happened for the 1969 model year. Knowing the last VIN of a month also reveals the first VIN of the following month. For December 1968 last VIN-first VIN works out to 18,125 units. Divide that by 20 work days equals 906 units/day, within the plus/minus 6 VIN margin. However, that calculation does not work out that closely for every month.

As I stated, a work in process. Got another data point so more number-crunching.

KurtS

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Re: New to this site!
« Reply #22 on: October 13, 2017, 04:14:26 AM »
Yup. My point (and John's) is normal is a very small range, mostly less than 10 or 12.
Your point is true - one of those oddballs could be the VIN that was recorded. Something for sure happened to the late NOR 68 recorded VIN's - those numbers are way off.
Kurt S
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