RoR Project PC1931 – JoHan Rides Again

RoR Project PC1931 – 1931 Cadillac 370® Indy 500™ Pace Car

            This grand example of what Detroit used to do best was quite a challenge to build. The Jo-Han® CG-431 base kit took extensive modifications to convert into this 370 Roadster but it was worth it. I’ve never seen another one like it in 1:25 scale. If you happen to see one let me know so I can compare research notes.

1931 Indy 500 Pace Car

     For this project I modified the base kit (Figure 1), a Jo-Han® #GC-431 Cabriolet model. Those kits are rather plentiful on the auction sites and can be had pretty reasonably even though they are forty years old. The reason is that although the kits were well engineered to replicate the actual car – they try to hard to replicate the original piece-by-piece and are very delicate and difficult to build. The other problem is that the kit’s instructions are pretty vague and in some cases incorrect. The biggest issue by far however, is the amount of flash on the parts. All of the above can be overcome by a modeler with moderate skills but when the flash is so thick that you can’t tell where the sprue ends and the parts begin – that’s a real Houston size problem, especially on chrome parts. I would have to say that the molding process and quality control of the parts were Jo-Han’s downfall. They had excellent engineering and subject matter choices but couldn’t mold a well produced model.

Figure 1

            The topside of the rear deck on the Cabriolet model has horizontal ribs that must be covered. Use a thin sheet (.010” thick) styrene (Figure 2) by cutting it to size and use some CA (super glue) to adhere it over the ribs.

Figure 2

            Cut out the wheel wells in the fenders on both sides and glue some of that thin styrene sheet into place to fill the hole (Figure 3).

Figure 3

            Add some modeling putty or filler to completely fill the gap (Figure 4) and finish it off with increasingly coarse grit of sandpaper.

Figure 4

            Glue the driver’s side golf bag storage door into place and fill it with finishing putty (Figure 5).

Figure 5

            Use a small drill of the same size hole as the original door handle to make a new hole to locate the door handle at the rear of the door (Figure 6). Make sure it’s the same distance from the edge as the original. Fill the front door handle hole in.           

Figure 6

            Cut out the door hinges at the rear of the door jamb with a sharp hobby knife (Figure 6a) and re-scribe the panel line there.

Figure 6a

            Fill in the spare tire mounting holes in the fenders and behind the cowl vent on both sides (Figure 7).

Figure 7

            Also fill in the notch along the fender (Figure 8). Use a piece of styrene square stock and fill the gaps with putty to finish them off.

Figure 8

            Fashion a few ribs and a center emblem for the running board fascia from styrene strip and a piece of round sprue (Figure 9).

Figure 9

            Glue them into place along that ridge (Figure 10).

Figure 10

     Primer the body parts to be painted white (Figure 11).

Figure 11

            Spray the parts a bright gloss white (Figure 13). 

Figure 13

            Discard the stock radiator cap and fashion one from round styrene stock or reach into your parts box and grab an old engine oil breather cap like this one (Figur 14) and secure it to the radiator shell.

Figure 14

            There is one glaring error in the kits instructions that deals with the cylinder head sub assembly (Figure 15). Note that in this photo you can see through the cylinder walls (black parts).

Figure 15

            The kit instructions show the cylinder assembly as one piece (Part #3) and do not mention the side walls needed to complete this assembly (Figure 16).

Figure 16

            Locate the cylinder head side walls (on the sprue tree next to the transmission halves). These do not have any part numbers assigned to them so you’ll have to find them by sight (Figure 17). The back sides of these parts have arrows that point to the front of the engine for proper orientation. Assemble these parts to the #3 part.  

Figure 17

            This is what the completed engine block will look like with all the pieces assembled (Figure 18).

Figure 18

            To modify the engine to emulate the 12 cylinder power plant used in the 370 roadster locate the exhaust manifolds and remove the two ports on each side shown    Remove the intake ports that are circled and use a small piece of sprue to add a port to the center of the manifold (Figure 20).

Figure 20

            This is what the completed (12 cylinder) engine will look like with the modifications (Figure 21).

Figure 21

            Assemble and detail the five tires by adding a chrome finish to the spokes and rims and the Fred Cady® decals to this model. Those are available on the online auction sites (Figure 22).

Figure 22

            Here is a look at the completed chassis with the wheels installed (Figure 23).

Figure 23

            Fabricate a spare tire mount from styrene pieces to mount to the bottom of the rear gas tank brace rod (Figure 24).

Figure 24

            Along with the excessive flash problem found on many parts there were also some parts with sinks (depressions caused by not “packing out” the part completely) such as on the front bumper (Figure 25). Strip the chrome in a bath of bleach, fill the sinks with putty and then chrome the bumper.

Figure 25

            Bare Metal Foil® was used here to provide the new finish (Figure 26).

Figure 26

            Apply some tempra paint to the body panels to add realism to those features (Figure 27). After it dries wipe off the excess with a damp soft tissue or cloth.

Figure 27

            Assemble the front end chrome parts with the hood and body tub in place to ensure proper alignment (Figure 28).

Figure 28

            At the back end add some turn signal red to those parts and some chrome trim to the rear deck ribs (Figure 29).

Figure 29

            Shape and paint the top of the dashboard black to include tapered ends at the edges of the top surface (Figure 30). Select and shape a piece of rectangular styrene stock for the top rail of the wrap around piece of the body tub.

Figure 30

            The completed dashboard assembly and window frame will look like this (Figure 31).

Figure 31

            The inner body panels should be painted cream and can be detailed with respect to handles, etc., in a variety of ways. Foil and paint were used here to emulate those features (Figure 32).

Figure 32

            Use a flat file to shave off some of the seat bottom. Especially at the rear of the seat to get it to set flush with the package shelf behind the seat (Figure 33).

Figure 33

            Apply the Fred Cady decals for the ’31 Pace Car. The words “Cadillac V-12” are a two piece application. Apply the gold lettering first and after it’s dry you can apply the black outline and the rest of the door logos in one piece (Figure 34).

Figure 34

            Because of some warpage to the golf bag access hatch and a poor fit in general you might consider just gluing the door into place on the passenger side with some epoxy glue. The yellow strips shown (Figure 35) are some tape used to keep the hatch in place while the glue dries.

Figure 35

            Another big omission in this kit was the lack of a handle for the rumble seat. Use the chrome center pivot hinge from one of the the landau’s to fabricate a realistic looking handle and adhere it to the center of the rumble seat panel (Figure 36).

Figure 36

            Finish off the interior according to the directions. Note that the pedal assembly straddles the steering mast jacket. Glue the body tub in place (Figure 37).

Figure 37

            Add the rear view mirror and convertible bonnet (Figure 38).

Figure 38

            Finish off this rare model by adding the foot pads, license plate holders and foil to the running boards and imagine yourself cruising the main roads home to Detroit after the big race!

Figure 39