In a prior conversion project I had requests for more detail on how I managed the drive, and as I think this drive came out well let’s take a closer look.

In part 2 I showed the basics of the drive, including adjusting the gauge of the power truck, but without the motor and everything wired up. Refer to that article as well for the early steps.

Based on an Athearn GP-7 drive

There are a lot of ways you could make a drive for this model. The basic thing to say clearly is that I like blue box Athearn drives, they convert well to OO, I have done this conversion a number of times.

For a Diesel switcher I like to use the original motor and drive one of the two trucks. There is simply not enough room to fit both drive trucks in place with the original motor, so I typically use either the unpowered truck from an AHM SW-1 or Alco S-2 on the other end. In this case, it was from a S-2 that I purchased in high school! All you have to do is widen the wheels out on the existing axles.

The unpowered truck is used for power pickup, so we have 8 wheels picking up power. It is mounted as below.

One lead is soldered to the harness on the top of the motor, and for the other I drilled and tapped a hole next to the motor to attach the wire to the frame directly.

Sideframes

The sideframes are from a AHM SW-1. For the powered truck I cut down the original sideframes to use them to hold the sideframe in place. For the non-powered truck, they are attached directly to the AHM truck.

Also in the above photo you can see one of the screws on this end that hold the frame to the body.

It’s tight and a bit light

For this to work at all I had to notch out the back of the AHM truck to clear the motor and cut back the fuel tank casting as far as possible. I’ve had to do this before. If the overall wheelbase of this engine was even 1/16 inch shorter it would not fit and I would have had to use a different motor.

Yet to be addressed is adding more weight to the model. I expect to add some weight inside the cab.

Couplers?

The good news is that there are holes set up in the right places for Kadee couplers! You will need their underset head couplers, however.

Bonus: Super Scale comparison

In the previous photo an engine is in the background, a Super Scale NW-2. It is an interesting comparison.

The Super Scale model is proportioned well, but the cab windows are a bit small and there are some clunky details. I’m now thinking though to rework that model a bit, in particular with better handrails.

When the series returns I’ll add more details and tackle the handrails.

Continue in SW-8 Series