Until the upcoming 3rd Rail Hiawatha passenger set is released, K-line is the only maker of an O scale 21" Superdome. These scale length aluminum cars are beautifully finished and capture the look and feel of the prototype. They are not exact models as I expect the 3rd rail set to be. The Superdome has some glaring errors, specifically the number and the non-flush construction of the dome windows, and the 4-wheel trucks. All the other cars in the prototype set rode on 4 wheel trucks, but the 200,000 lb Superdome required 6 wheel trucks. A couple of years ago, I had read on the forum about a modeler who did conversions using 6-wheel trucks from MTH's full dome cars. I managed to acquire a wrecked MTH dome car to salvage the trucks. I put the project on the back burner when I read that the wheel openings needed to be enlarged for clearance.
Well, I pulled out the project and I was pleased to discover that the trucks fit nicely without enlarging the wheel openings. It was actually a very simple conversion.
One small screw holds this truck mounting plate to the floor. Separate it from the floor the remove the C-clip on the truck kingpin. Finally detach the center roller and ground wires, and put the old 4-wheel truck aside. The only modification required is to drill a new 1/8" mounting hole for the MTH truck mounting screw. In the photo below, the large hole on the left center is for the wires, to the right of that is the old truck mounting hole, and 7/16" to the right of that is the new 1/8" hole for the MTH truck screw. This location centers the truck perfectly in the wheel opening. You will need to ream out the 1/8" hole a little larger to clear the MTH screw.
Here is the screw installed in the new hole. Ignore the washer. I thought I needed it to match the car height, but the height was spot on without it.
Now route the two wires through the large hole (from underneath as pictured above - I got one backwards when I wasn't paying attention). Connect the red wire to the center roller pickup screw, and the black wire to the other screw. The MTH pickup screw heads will be very close to the mounting plate, so to avoid shorts, I stuck a piece of black electrical tape on the plate above the screws. Now attach the truck to the mounting plate with the MTH screw through to 1/8" hole. I used a tiny bit of blue locktite on the threads. Lastly, reattach the mounting plate to the truck floor and bend the wires so the truck swivels freely. The MTH screw head is a little large so the mounting plate bulges a little, but does not affect anything. I had a reattached the mounting plate so many times while working this out, that the screw no longer held, so I had to use a larger screw from my junk box.
Here is the result:
I plan some other future improvements to the car that have already been done by other forum members. Paul Fischer repainted and reconfigured the interior of his Superdome to have all the passengers facing forward:
Dan986 did a nice job adding extra window dividers using vinyl stripes to improve the side window count from 10 to 20 windows in his 18" car (prototype is 21):
I'll do the same with my 21" car with 12 side windows. I also picked up a bottle of Alcad green to tint the windows. And I really need more passengers!
Bob
