St Louis Assy Plant... Roger Stephens

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  • Michael H.
    Expired
    • January 29, 2008
    • 7477

    #1

    St Louis Assy Plant... Roger Stephens

    On Wednesday morning, Roger Stephens brought up and interesting question about the St. Louis plant. He asked "how many Corvettes would normally be in actual production, or in the building, at any given time during a work day". I replied that it was an interesting question and that I would try to come up with a figure in a day or two. I've since decided that there's likely no way I will ever be able to come up with an accurate figure. I've been looking at paperwork and the plant blueprint for three days and still have no actual numbers.

    First of all, we have to decide when a "Corvette" actually becomes a Corvette. If we assume that point is when the body is installed on the chassis, or when the engine first comes to life, it would be a bit easier to calculate the total. However, I decided to include all of the units, even though they were just sub assy's. The most logical way to come up with a total would be to begin the count with the body line since it's the longest line of all the sub assemblies (slightly over 1/4 mile) and requires the most time for the build. So the count begins the minute a floor pan is placed on a body truck. Since the body line is one continuous winding loop that ends/starts at the same spot, it would have been easy to calculate the number of bodies on that line. However, the body gring booth and paint operation booths completely destroy any chance of an accurate count as this is the only point in the journey that the body trucks are not equally spaced. The number of bodies in production, minus the body grind and paint booths would be just about exactly 73. We can probably add roughly 15 to this total for bodies in paint booths.

    Next comes the chassis line, counting from the point of body drop and beyond. There are exactly 12 jobs on that line.

    The next two possible lines are the two that have jobs the need paint touch up and those that don't. (most did) There could have been as many as 16 jobs on either of these lines.

    Last big one is the "final trim line" that was 380' long and ran across the rear of the bldg. There were 19 jobs on that line at the end of production in 82. (18 in 64)

    These numbers do not include any of the many individual stations such as water test, brake test and front end align etc etc. Add aprox 10 for these stations.

    The "repair area" had 21 machanic stalls and at least half were usually filled.

    If we count all but the mechanical repair area jobs, we come up with somewhere around 135 Corvettes for a total. (hope I have all the math right) That's a lot of cars for a building that was only roughly 400'X 600'.
  • Wayne W.
    Extremely Frequent Poster
    • May 1, 1982
    • 3605

    #2
    Re: St Louis Assy Plant... Roger Stephens

    So from the time the body was placed on the buck to the time it was ready for paint would be? If there was a deviation on the line (emergency modificton), how many would likely be effected in a day. How does this compare to the AOS body line?

    Comment

    • Michael H.
      Expired
      • January 29, 2008
      • 7477

      #3
      Re: St Louis Assy Plant... Roger Stephens

      wayne,

      From the time the floor pan is clamped in placed on the body truck, to a point where the complete assembled bare body is rolling into 1st prime, roughly 5 1/2 to 6 hours have passed. This would be the time required for the C2 era bodies. (C1 required more time and C3 less)

      The body, at this point, is complete including doors, hood and deck lid for conv. All panel adjustments have been completed and it's been through the "body grind booth" where all seams and problem areas are ground smooth.

      The body remains on the body truck throughout the entire body build process. The body truck mounting points are dimensionally exactly the same as a properly shimmed frame so when the body is eventually removed from the body truck and placed on it's frame, there will have been zero change in dimension or panel fit.

      The body moves through the entire body build process at a speed of roughly 2 feet per minute for the C2 era cars. (that doesn't include the time in the prime/paint booths where the body is temporarily stationary)

      Comment

      • Michael H.
        Expired
        • January 29, 2008
        • 7477

        #4
        Beginning And End Of Body Line

        On the right is a complete painted and trimmed (mechanical trim) body ready to be picked up off the body truck and placed on it's chassis. (not shown) On the left is the beginning of the process as it starts over again with the rear half of a floor pan locked in place on the body truck. Five hours later, the first coat of primer will be applied to the body that will have been built on this floor pan.




        Comment

        • Roger S.
          Expired
          • June 1, 2003
          • 262

          #5
          Re: St Louis Assy Plant... Roger Stephens

          At what point was the trim tag attached to the body? On the early 70's I understand it was after the body was painted. Was it before the trim lines or just before the body was raise off the truck? It looks like on average 130 cars per shift came off the assembly line for 1973. I have been reading Birthplace of Legends, and enjoying the pictures and drawing of the assembly line- page 66/67, and in building my 73 database/registry I am wondering how many cars may have come off the assembly line the same day as started and the same day as the trim tag was applied.
          What was/is considered the end of production for a car? When it came off the assembly line or when it was out of the repair area?

          Roger

          Comment

          • Jack H.
            Extremely Frequent Poster
            • April 1, 1990
            • 9893

            #6
            We can 'bound' the answer...

            Since job numbers ranged from 0-500 before starting over, 500 HAS to be a comfortable upper limit to the number of vehicles being assembled in-plant on any given day (including those pulled and set aside for repair, Etc.). Otherwise, there was the possibility of mistake/confusion. Now, just how much design 'safety margin' was in that 500 number I've got no earthly....

            Comment

            • Michael H.
              Expired
              • January 29, 2008
              • 7477

              #7
              Re: We can 'bound' the answer...

              Jack,

              The 1-500 body number wasn't related to daily production. The number I posted above would be close to the total number of units being assembled at any given moment, not counting the number of units in repair. Guessing, I would think the upper limit of units in that plant at any time would likely be in the range of 150-160.

              Comment

              • Michael H.
                Expired
                • January 29, 2008
                • 7477

                #8
                Re: St Louis Assy Plant... Roger Stephens

                Roger,

                The trim tag on C2 and C3 was attached soon after the final color coat went on but before blackout and final bake/reflow. At that point, the body had a LONG way to go before it was ready to be installed on the chassis.

                The body left the paint area and entered an area called "trim", but that wouldn't be the type of trim we would normally associate with the word. This "trim line" was for "hard trim", such as heater/AC, wiring, inst panel, body emblems, glass and mldgs etc etc. Hard mechanical parts.

                I suppose it's possible for a car to leave the building on the same date as the trim tag date but I think it would be more likely the day after. There was still a lot of car to build at that point. I'll see if I can find the time required after the paint operation, see if it's possible to have a complete unit on the same day.

                Not sure but I believe the first of the painted trim tags began at the BG plant, not St Louis, but I may be wrong.

                The end of production was the point where the unit rolled out the door and headed for the Complete Auto Transit storage lot.

                Comment

                • Anthony F.
                  Expired
                  • December 1, 1985
                  • 191

                  #9
                  Re: St Louis Assy Plant... Roger Stephens

                  Roger,

                  Let me help out a little on some of your question here.

                  The units received the broadcast copy on the front of the body as a build aid also when it first arrived in Trim. The trim & vin plates were attached as the body came into Trim (Hard Trim to some) and checked against the broadcast. The date & trim information was stamped on the trim tag when the unit passed the operation that attached the plates. The vin was also stamped at the operation by the same operator.

                  The location of this operation varied slightly during the model years but was generally in the first group. Explaining the “group”; Trim Department was and still is divided into multiple work groups that are the responsibility of supervisors. Bowling Green Trim Department started with 5 groups while St. Louis’s Hard Trim had 3 groups and Soft Trim had 1 group.

                  To help answer your next 2 questions:

                  What was/is considered the end of production for a car?
                  When it came off the assembly line or when it was out of the repair area?

                  The Final Trim Line (Soft Trim) had a “Pay Point” . This was an unmarked line in the floor where the Corvette Organization considered the unit “Built”. For business reasons there had to be a point where the car became a car, not parts. So this point on the Final Trim Line around the inspectors location was chosen. A daily report was submitted counting the numbers of job built and the plant received build credit from GM for that amount, as I have been told, thus the term “Pay Point”. This also the point where the yearly inventory checks concluded that a car was complete and not parts. Also for Tax purposes and other totals.

                  After the Pay Point there was a repair area, inspection build process and audit before the job was shipped from the Corvette Organization to the yard and transportation operations.

                  You mentioned that you have been looking at the book “Birthplace of Legends” so look at page 66.
                  Before you try to pick a point on that picture remember that it states that it is not to scale AND it is not completely accurate for your purpose. That drawing need to be taken into account that it was during the AO Smith years and is general in content. During the 73’s build the body is completely different, Trim Line is different and both the Paint line & Final Line are longer but not joined.

                  Now, look at the right hand side of the page towards the top that says repair area. You could, in general, consider the area prior to that repair area the Pay Point.

                  I hope this helps you and others understand that the plant was an evolving business and changed with the production needs to increase production, improve performance and solve other problems. I started in St. Louis in September 1962, transferred to Bowling Green in May 1980 and then retired in June 1992.

                  Comment

                  • Joseph T.
                    Expired
                    • May 1, 1976
                    • 2074

                    #10
                    Re: St Louis Assy Plant...

                    Tony

                    I was told that in 1955..the total car building process at one point was done entirely by 5 guys.

                    Joe

                    Comment

                    • Anthony F.
                      Expired
                      • December 1, 1985
                      • 191

                      #11
                      Re: St Louis Assy Plant...

                      Joe,
                      I was told by the “old guys,” when I started at the plant, that the whole car was built in just the length of the building along the rail road tracks on Natural Bridge. The width of the line was one aisle wide. Similar to the pictures we see of the Flint build process.
                      When I started in 62 that area included the office area, small parts, birdcage/ spot weld and cafeteria.

                      Comment

                      • John H.
                        Beyond Control Poster
                        • December 1, 1997
                        • 16513

                        #12
                        Re: We can 'bound' the answer...

                        Jack -

                        The "500" quantity was chosen by the Production Control Department as the number of units in each "schedule"; each "schedule" made up a "deck" which constituted a grouping for ordering production parts. After dealer orders were accepted by the plant for production, they were grouped in 500-unit "schedules", and the computers "exploded" those orders based on style, color, trim, options, and the applicable ECL's against the Engineering Parts List to generate a listing of parts required in the plant to build those 500 units, and that's how production material procurement was done - in lots of 500 cars.

                        A rubber stamp is frequently seen on the back of the "Corvette Order" (not the "Corvette Order Copy", which was the "tank sticker") which is the schedule and unit number; "23 349", for instance, would be the 349th unit in schedule #23.

                        Comment

                        • Roger S.
                          Expired
                          • June 1, 2003
                          • 262

                          #13
                          Re: We can 'bound' the answer...

                          This schedule and unit number, is this the same number that is on the 'build sheet'in box 10? Talking about the 1973 model year. I have numbers that the last three number are greater than 500 - in the 700's. Also I have collected build sheet info that shows the first two numbers appear to increase each day.
                          Roger

                          Comment

                          • Tom R.
                            Extremely Frequent Poster
                            • July 1, 1993
                            • 3963

                            #14
                            Painted Trim Tags

                            Roger:

                            Tony makes some good points in his comments...in 73 production was approx 25,000. By the end of the 70's, it doubled therefore affecting production methods rather significantly. I had a chance to meet and talk with a process engineer who was in the St Louis plant during the 70s and gave me some production numbers per day but I would have to look those up.

                            But trim tags began to appear with paint on them in the 75-76 period due to the relocation of the trim tag station from the beginning of the trim line back to a point between paint booth 1 and paint booth 2. This was also the point of VIN tag install. VIN tags were pre-assigned each day for the day's production and were pre-stamped. These were legal documents and therefore handled and documented as such. By the time production moved to Bowling Green...tags were installed after paint operations.

                            Also...most of the discussion thread focused on late 60 and early 70 production and the use of the build sheet in 73 differed significantly from the tank sticker delivered with Corvettes prior to 73. Most on the thread here probably would not be familiar with Box 10 on the build sheet so help them out by explaining it in detail. Your comparing to different era's of Corvette production.
                            Tom Russo

                            78 SA NCRS 5 Star Bowtie
                            78 Pace Car L82 M21
                            00 MY/TR/Conv

                            Comment

                            • John H.
                              Beyond Control Poster
                              • December 1, 1997
                              • 16513

                              #15
                              Re: We can 'bound' the answer...

                              Roger -

                              Dunno - I have no knowledge of the details of build documents after 1967, or what's in "box 10" on the C3 build sheets. Terry McManmon may have the answer for you.

                              Comment

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