My Atlas Alco RS-1 (GM&O 1108) came with Rapido-style couplers, so replacing them with knuckle couplers was a high priority. Fortunately, MicroTrains makes a body-mount upgrade kit for this exact locomotive that makes the conversion very easy. I picked up the MT #1158 coupler conversion kit from Fifer Hobby Supply along with my latest order and set to work.
The pre-1998 Kato-built Atlas RS-1 models such as this one have truck-mounted Rapido couplers and consequently have rather large, unprototypical holes in the pilots. The #1158 kit includes two filler panels that are an exact fit for these openings and give a nice looking pilot, though the color of the plastic is slightly different. Nothing a little weathering won’t cure. The kit also includes two pre-assembled couplers, three mounting screws (in case you lose one) and a small strip of metal.
The first step in the process is to cut the old coupler housings off the trucks. To do this, you place some tape over the gear holes in the truck, remove the old coupler and spring, slide the metal strip between the truck and the locomotive frame under the coupler, and saw away. I used an Atlas Super Track Saw for this, but any good, sharp, small razor saw will do. The truck sideframes extend slightly beyond the ideal spot for sawing, so be careful not to cut them.
Alas, my camera wasn’t working, so I have no more in-progress shots. We’ll make do, though.
Here you can see the installed coupler. The next step in the process is to mark and drill the holes. The kit instructions say to lightly glue the pilot insert in place, and then drill and tap the frame through the hole in the insert. I didn’t get it glued quite right, but it slips right into place, so it’s hard to get this part wrong. Once you’ve drilled and tapped the screw hole, just slip the coupler through the hole in the pilot, drop the screw through the coupler, and screw the assembly into the locomotive frame.
One catch. The included screw is too long. You will need to cut it down short enough that it doesn’t stick up through the deck on the locomotive frame. In my case, I cut it off after screwing it in place because I had accidentally drilled all the way through.
Here’s a parting shot of the new pilot with the knuckle coupler…