C3 1981 Frame Stencil

[Fred S.]

The Corvette Assembly Instruction Manual list the frame number as 14020218.....is this the same for automatics and 4 speed? Vette is 1981, L81, 190 hp, automatic late Aug. 81 build at Bowling Green. Thanks

[Michael J.]

Re: C3 1981 Frame Stencil

I believe the '81s had the same frame regardless of transmission, the TIM&JG states both had a bolted cross member regardless of transmission, unlike the '80s. You should see the frame stencil, and just inboard on the back side of the passenger side footwell you should see a grease penciled VIN derivative (last 4 digits). Here are pictures of my very early August built '81 automatic.

[Fred S.]

Re: C3 1981 Frame Stencil

Mike, thanks for the response. I suspect that the assembly manual number is not correct because although most of my part number is illegible, I can read #140??14? which would correspond with your actual part number. My date reads ??-8-8? Since both vettes are Aug. builds, it would make sense that the part numbers would be the same. Also I do have the grease penciled VIN derivative on the footwell. Do you know what the - suffix number after the part number is and/or how it is determined?

[Michael J.]

Re: C3 1981 Frame Stencil

I think your frame part number is correct as well. Mine is a 5,000 mile all original I am starting through Bowtie judging. I do not know what that suffix number refers to, but now you have me curious so I will ask the team lead when it is judged for Bowtie sign off at the regional soon. What is your last 4 VIN? Mine is 2509, as you can see. The first BG built cars are very neat. Is yours a tu-tone too?

[Fred S.]

Re: C3 1981 Frame Stencil

Mike, my 81 is silver over blue with s/n 6114 and 24,000 miles; previous owner triple crowned the car back in early '90s....the reason I thought that the manual number was not correct for my car was that the remaining visable digits on my frame do not correspond but do correspond to your part number; the car is still all original and we plan to take it to the national this July.

[Michael J.]

Re: C3 1981 Frame Stencil

That's great Fred, I look forward to seeing it in Warwick. Best of luck on your judging, sounds like it will do very well.

My first new Corvette was an '81 (beige/bronze), long before I ever heard of NCRS, but I loved the car (had to sell it when we had kids) and always wanted to get another when I got older. Not many '81 fans around here, but I just had this claret/dark claret one judged for the first time ever at the Arizona Chapter last weekend and it was very popular among the crowd (even won "Ladies Choice") because you hardly ever see them at NCRS meets. I like the less popular cars, I have two '64s, and we made up a special T-shirt "Secret Society of the '64". I am thinking of having one done that says "Secret Society of the '81".

[Tom R.]

Re: C3 1981 Frame Stencil

Also I do have the grease penciled VIN derivative on the footwell.

In the late model C3 years when GMAD sported its landscape style buildsheet, in the schedule box was listed the schedule number and job number. The footwell was used to write the job number. This practice was consistent with St Louis built Corvettes. I have only studied one Bowling Green Corvette 7772 (1982) and noted that the footwell yellow hand-scratched number corresponded to the VIN...which was also in the schedule box. You BG built owners may be onto something here where the job number became this quasi VIN derivative that marked a particular chassis as a mate to the body on the other side of the factory.

Do you know what the - suffix number after the part number is and/or how it is determined?

The suffix is the lot number. In other words, if you find a bunch of frames with the same date, the likilihood is that the lot numbers are the same or within a digit or two. I have tracked Pace Car frame stencil numbers for both four-speed and M38 over the years and have seen this pattern. The lot number increases as the date moves forward toward the end production date. In 1978, a lot more M38 frames were assembled than four-speed so there are a lot more...lot numbers used.

[Fred S.]

Re: C3 1981 Frame Stencil

Tom, my 81 is BG vin 6114.....the buildsheet shows job seq #C0 064806 and Sched No. date 40-6114 / 08-25. The footwell shows the sched. number 6114; however what I did discover from the buildsheet was that it listed the last three digits of the frame number which confirms my previous correspondence with Michael Johnson where I was trying to confirm a number that was obtained from the Corvette Assembly Manual. Not sure why the manual number is different. It makes sense that Michael's 81 and my 81 would have the same frame number especially since both are Aug. 81 builds. Thanks for your response.
Fred Sarbello 81 and 70LT1

[Michael J.]

Re: C3 1981 Frame Stencil

In the late model C3 years when GMAD sported its landscape style buildsheet, in the schedule box was listed the schedule number and job number. The footwell was used to write the job number. This practice was consistent with St Louis built Corvettes. I have only studied one Bowling Green Corvette 7772 and noted that the footwell yellow hand-scratched number corresponded to the VIN...which was also in the schedule box. You BG built owners may be onto something here where the job number became this quasi VIN derivative that marked a particular chassis as a mate to the body on the other side of the factory.



The suffix is the lot number. In other words, if you find a bunch of frames with the same date, the likilihood is that the lot numbers are the same or within a digit or two. I have tracked Pace Car frame stencil numbers for both four-speed and M38 over the years and have seen this pattern. The lot number increases as the date moves forward toward the end production date. In 1978, a lot more M38 frames were assembled than four-speed so there are a lot more...lot numbers used.

Tom, thanks much for that info. I have found the early BG cars to be pretty interesting, and since only 1 '81 has ever been through Bowtie judging (and I understand it was a St. Louis build) in NCRS history, I wanted to take my very well preserved low mile, early BG car through Bowtie judging so maybe we can all learn more.
Mike

[Fred S.]

Re: C3 1981 Frame Stencil

Michael, now that we know the frame suffix number was a lot number, what was your complete suffix? your photo did show -3?? Maybe I can find that also on my build sheet.
Thanks
Fred

[Michael J.]

Re: C3 1981 Frame Stencil

I have my build sheet too, there is a job sequence # (upper left corner) which is not the VIN, below that is the sched. no. and date, which is 17 and the last 4 of the VIN and 07-30, but it was actually built August 3, and for frame it only says 144. I am leaving in a few minutes for a trip and will check the frame suffix when I get back.

[Tom R.]

Re: C3 1981 Frame Stencil

So Fred, what box number as used to broadcast the last three digits of the frame assembly number? And it is the frame assenbly number and not the lot number?

I just checked my inventory of buildsheets and see the 144 number in box 12...and all the 81 sheets have the 144 number...including the St Louis built 81. But the St Louis built Corvette does not show the VIN derivative in the schedule box...rather it shows the traditional job number. In fact, in all my study of buildsheets, I had not correlated that box 12 frame three-digit number with that of the last three digits of the frame assembly number. And it reconciles nicely with frame assembly part numbers both four-speed and auto. For example, in 1978, 981 was the four-speed and 982 was the auto frame assembly.

See in the early years of the GMAD buildsheet, the codes broadcast were primarily chassis. Over the years, more codes were broadcast. I even see the frame assembly number derivative back in 1973. Nice job guys!

[Fred S.]

Re: C3 1981 Frame Stencil

Tom, the number 144 was listed in "box 12 Frame". Michael Johson's actual frame number which also ends with 144 is also listed on his build sheet as 144 and his suffix as stenciled on his frame, starts with -3. So what is the frame assembly part number and where do I find it? The corvette assembly manual lists the frame number as 14020218 which is not what is on my frame. Thanks

[Tom R.]

Re: C3 1981 Frame Stencil

See if there was a change order note at the bottom of the AIM sheet. What appears on the AIM does not reconcile with either the buildsheet or MJ shipped vehicle. The buildsheet is what a factory worker would have been looking for...he would not want to screw it up.

[Fred S.]

Re: C3 1981 Frame Stencil

Tom, OK sorry but what is the AIM sheet and what is MJ shipped? Thanks, Fred