This page describes how I converted this car from the toy-train couplers and wheels to the scale ones. It is an easy process. The S-Helper Service box comes complete with the scale wheels, but you will have to buy the scale couplers separately. I decided to purchase a set of S-Helper Service couplers (part number 01295 - provides four couplers). The only tools required for this project are a set of small, jewelers screwdrivers, tweezers, and perhaps a magnifying visor. The first photo shows the car as it comes out of the box. It has the large American Flyer-compatible couplers and wheels with large flanges.
This is a close-up photo of the original wheels, truck, and coupler. The coupler is effectively truck-mounted.
The first step is to remove the truck. I had a hard time with removing the screws. They are in there very tight. Be careful of the small washer in the truck, because it is easy to get lost. The wheels can be removed by slightly widening the truck. For one truck this was very difficult, for the other the wheels practically fell out. Once the first wheel is out, the other one is easy to remove.
These are the new parts. I was very impressed with S-Helper Service's fore-thought to us scale modelers. I was fully prepared to have to cut the shim off of the old coupler, but when I opened the package of the wheels, I discovered that they provide us with a replacement shim (seen here in the lower-left corner of the photo).
Before placing the truck back on the model, I installed the new S-Helper Service couplers. The car is already set up to take the screws for the coupler (as well as the Kadee S-scale coupler). I found it easiest to install the two screws on the outside edges first. The center screw is seen on the car's floor, and the new truck shim is already in place in this photo.
Next, I installed the center screw. If you look closely at the photo, you may see that the center screw isn't all the way down. If you tighten it too much, the coupler will not move freely. Also, I found I needed to loosen the screw just a bit more so that the coupler would return back to its center position.
And here is the finished model. The truck fits nicely in between the pins on the shim, and is then attached with the screw. I usually tighten the screw all the way and then back it off a half turn or so to allow the wheel some sideways motion. All-in-all, this was a simple project. The hardest part was loosening the trucks' screws. S-Helper Service provides us with all we need to easily convert these cars to scale. The visual difference between the toy couplers and the scale ones is significant. Since I don't plan on using uncoupling magnets, I will most likely cut off the trip pin on the coupler. However, that will be done later when I further detail this car. The scale wheels exactly matched the NMRA S-scale gage.
Update: I have decided that the HO-scale Proto Max couplers are going to be my fleet standard. The next photo shows that coupler installed. Note that I use only the center screw. In a heavy crash, the coupler can move, but most of the time, it stays put. For some of my cars I have put a drop of superglue in the back of the coupler where it meets the floor of the car.