4th Post
Hemi-powered cars merit special mention. Their rear frame reinforcement plates are welded on to the frame rails at the stamping plant, creating a special trunk floor sub-assembly to be stored and then used at Lynch Road. Approximately one Hemi-car per shift is assembled (two shifts per day; the third shift is for plant maintenance).
Before exiting the metal shop fabrication area, every body receives its very own premade fender tag. It is attached to the left inner fender by its forward screw only, then pulled up at its rear. This allows inspector's punches to be impressed on it later, and allows the primers and color coats to be applied under it. (This is not a universal practice on every car or at all plants; sometimes the tag is hung inside the car by a paper clip).
Another vital task of the Metal Shop is embossing "secret" portions of the VIN on at least two pieces of welded-on sheet metal of the car. This is accomplished with an air or hydraulic embossing tool containing numbers and letters, manually located and actuated by its operator.
Since we are building a SuperBird, the work of the Metal Shop is still not finished. Every special part to be welded on and/or color-coated must be installed in this area. Most of this work will be done in "repair holes," which are side-tracks off the main assembly line. The major parts to be welded in are the rear window plug, wing support plates under the quarter panels, trunk floor brace brackets, and the hood latch tray mounting bracket.
The major bolted-on parts are the modified 1970 Coronet hood and fenders. The front section replacement work on the hood is done at the Chrysler stamping plant, while the more minor fender modifications are done at Lynch Road in the Metal Shop. Many special holes are drilled in the body for the wing, the 1968-69 Charger vacuum headlight system, and the fender scoops. Some usual Road Runner holes are not drilled, such as those for the metal nameplates on the quarter panels.
When the special-body modifications are completed on the SuperBird, it rejoins all other completed bodies in a holding area at the end of Body-In-White. From here, cars are selected at random for insertion on the Paint Shop line. The Sequence Number of each car is sent ahead via computer to the Paint Shop.
Every car begins its trip through Paint Shop with a trip through a seven-part, full-body spray and partial immersion in a series of chemical applications.
1. Hot chemical cleaner to remove waxy die-drawing compound, dirt, joint-leading residue.
2. Hot rinse.
3. Another hot rinse.
4. Paint anchoring, metal etching and coating phosphate solution.
5. Cold rinse.
6. Conditioning solution.
7. Dip up to headlamp level in grey water-based primer. Before this has dried, outer body is hosed off to prevent paint ridges caused by this primer, which would show through the color coat.
The first six of these steps are the "Bondurite" cleaning and coating process. The final dip in primer is a Chrysler-invented step in corrosion protection, begun with the 1960 model year. Through all of these operations, the body is supported by large hooks, the forward of which pass through the windshield opening and attach to the dash panel area. The rear hooks attach in the wheel tub area. The hood and deck lid remain open to avoid large amounts of the chemicals becoming trapped in them. The many stamped-out large holes in the floor pans allow the chemicals to drain out. Passage through a dry-off oven dries the Chrysler Chemical Corp.-manufactured dip primer, and evaporates any water wash residue.
Now the SuperBird body requires another special step, the application of heat-curing "Plastisol" one-part filler around the rear window plug. Since the car will have a vinyl roof (purposely), only shaping and rough sanding of the joint area is necessary. This avoids the time-consuming (and toxic) joint-leading process that is performed at the roof-quarter joints on all cars without a vinyl roof.
Body sealers are now applied to all cars. A black, tar-like sealer is applied to all passenger compartment floor joints. This same always-soft material was used in the trunk compartment area until the wife of Chrysler President Lynn Townsend found that her luggage once was marred by it. That episode resulted in a corporate switch to the much more expensive, hard-drying Plastisol white sealer in the trunk! This sealer is also used in the joints around the rear window panel, and similar outer-body joints. Sound deadener is sprayed on the inside of the quarter panels as accessible from inside the trunk compartment, and to the inside of the door skins.
Now it is time to prime the body. All cars, regardless of body color, use a dark grey primer. Workers in the prime booth spray the door openings, and under/inside the hood/deck areas. Dummy, recycled 1/4" wire latches keep the doors, hood, and deck lid shut. Robot guns on curved tracks spray the sides, roof, hood, and deck lid outer body, their spraying actions programmed according to the car's body style. The insides of the car, and the underside receive only overspray.
Booth overspray is collected by water that flows downward all along the sides of the spray booth and over to its center, where it catches the paint particles in the downdraft through the open steel gridwork floor.
The "Upper Door Frame" (UDF) color is sprayed on any inside metal of the body shell that will not be covered by upholstery or metal finish panels. This colored paint is sprayed on before the primer overspray has dried.
Cars remain in the primer baking oven for approximately twenty-five minutes at 350-375 degrees. This high heat is intended also to cure the weld primers and vinyl plastisol sealers, which were applied with a gun to panel joints prior to being welded together.
The primer is wet-sanded at Lynch Road, using power disc hand-sanders, which have built-in water sprayers. Only the outside of the body is sanded. Following a wipe-off of primer residue, the body is cleaned with naphtha, then wiped with an alcohol-and-water solution. The UDF color is masked off by hand, with tape and masking paper.
Since our sample SuperBird is basically a 1970 Road Runner, its tail lamp bezels have been attached to the tail light panel with their purposely-long studs, while being spaced from the panel with one-inch sleeves. This allows the bezels to be painted with the car body, and allows painting of the tail-light panel contact areas, preventing rust. After the paint is baked, the sleeves are removed, and the bezels are permanently attached.
It is essential to note that a primary goal of assembly line painting of all cars is to have every part of the car that will be color-coated be permanently attached to the body before it enters the paint booth. This prevents the inevitable paint scratching of subsequent painted-parts assembly. Also, parts that are not to be color-coated are not installed on the car prior to entering the paint booth, thus avoiding masking off.
The front valance panels present a problem unique to SuperBirds. (They are the body panels that attach to the fenders forward of the wheels, and are later bolted to the nose cone supports [bumper brackets]). The valance panels cannot be attached to the fender during painting because they would hang down at their underbelly end and get caught all along the assembly line. Yet, the valances are in an area of high rust potential, and must be color-coated.
The solution was to make them of galvanized steel, eliminating the need to run them through the Bondurite system. For color-coating, the valances are hung with short wires from the roof rails inside the passenger compartment, and painted there by the workers while the car was in the color paint booth. (This was a later standard practice on cars with bolted-on front or rear valance panels).
The SuperBirds' rear window lower "corner" pot metal trim pieces are another painting problem, because they cannot be attached to the body during color-coating. Painting of the underlying sheet metal is necessary to avoid rust, and the trim pieces are painted body color and flat back. So, they are supplied to Lynch Road already color-coated for each allowed SuperBird color.
The baking oven for the color coat has a temperature of about 250 degrees, and baking time is twenty to thirty minutes. If a car comes out of the oven with paint problems, (usually dirt, sags, or drips) it goes to a Paint Shop repair hole. There the finish in the problem area is correctly prepared, the surrounding area is masked off, color-coating is applied, and the car is sent to the repair area's oven.
Those rare cars (fleet cars, usually) that are to be two-toned (painted metal roof different than body color), are removed from the exit line of the baking oven. They are placed on the entrance line to the paint booth, where the lower body is masked off. In the paint booth the roof color is sprayed, then the car passes through a baking oven again.
No color coat is applied to the roof of cars that will receive a vinyl roof, greatly cutting the use of expensive finish paint. Vinyl roofs are installed in the Paint Shop after a car's exit from the baking oven. This includes our sample SuperBird, which passes through the adhesive spray booth, then gets its mandatory black vinyl roof, specially-cut to fit the semi-fastback rear window plug. They may also apply decorative stripes to other models, particularly if the stripes are installed before body fittings that cover portions of the stripes. Station wagon woodgrain decals are applied by Paint Shop workers.
Now is a good time to illustrate one of the assembly line problems caused by the special-ordered SuperBirds. Our tour guide through time, Engineer Gil, distinctly remembers one SuperBird that was painted a color not allowed for SuperBirds.