HO Scale Proto 2000 to Kato Drive Conversion Frame
Proto 2000 GP7 and 9’s are well known for fantastic detail but suffer from electrical pickup issues, cracked gears, and mediocre motor performance.
To achieve perfect running Proto 2000 Geep’s for my layout I resolved myself to the fact that I would, at a minimum, need to replace the motor and upgrade the electrical pickup.
While replacing the motor is possible by utilizing the stock frame, heavy modification is required and still leaves a less-than-desirable electrical pickup path from the trucks and the dreaded cracked gears.
How about a full-frame replacement… Challenge accepted!
The challenge was to engineer a frame that would accept a Kato motor, Kato trucks, sound decoder with keep-alive, and speaker, while still being reasonably heavy. All while fitting into a Proto 2000 GP shell with only the light tube needing modification.
My final design meets all of those requirements and more! The frame goes together in just a few minutes, DDC decoder installation is a breeze, and everything fits perfectly into the Proto 2000 GP7 or GP9 shell. The final weight is approximately 14oz, the same weight as a stock Proto 2000 GP7 that has not been milled to accept a DCC decoder or sound.
The conversion frame will also fit a Proto 2000 GP18 with minor modifications to the shell, more on that later.
Kato Motor and Trucks
The conversion frame is designed to accept a Kato drive that can be scavenged from any Stewart/Kato FA or FB unit. These can be found all over eBay and train shows, typically selling in the $40.00 – 50.00 dollar price range.
The Kato motor and trucks are a drop in fit. No modifications to the Kato components are needed. The conversion also includes a plastic tray that carries the steel weights but more importantly, it separates the decoder wiring from the drive components.
One additional feature, the plastic fuel tank can be screwed to the frame if you choose, no more sticky tape holding your fuel tank in place!
The Shell Game
Proto 2000 GP models have gone through changes over the years and some later GP9 and GP 18 shells will require small modifications to fit.
- GP7’s and GP9’s with screw mounts as shown in Figure 1 require no modification.
- GP9’s that use tabs to mount the shell to the frame as shown in Figure 2 will require modification. The tabs need to be clipped off, they typically break off anyway. The shell will be held in place by the coupler pockets.
- GP18’s came with coupler mounts cast into the frame as shown in Figure 3. The tabs need to be clipped off and I will provide coupler pockets in those kits.
Performance and Final Weight
What can I say, “It runs like a Kato”. Your locomotive will crawl at a snail’s pace! Your locomotive will be smooth and quiet! Your locomotive will have minimal amp draw compared to the stock motor. The electrical pickup will be outstanding, and your keep alive will last much longer with the lower amp draw Kato motor.
Locomotive Weight
A stock Proto 2000 GP7 that has not been milled to accept a DCC decoder or speaker weighs in at 14oz. Once milled out for DCC and sound the weight is reduced to approximately 10 or 11 oz.
My goal was to achieve a weight close to that of a stock GP7 and I accomplished that by making the frame out of brass bar stock with steel weights making up the remaining weight deficit in the full kit.
My first attempts were in aluminum but the frame was too light and not enough weight could be added in the small space available inside the Geep shells.
Light Tube Modification
When installing DCC and Sound into Proto 2000 GP’s it is typical to have to modify the light tube and that’s no different with this frame conversion.
The light tubes are easily removed with needle nose pliers. I cut my light tubes as shown in the pictures.
Once the tubes are cut they can be reinserted into the shell. I don’t glue them in place. I use some black acrylic paint around the inside of the shell and light light tube to hold it in place. The paint is translucent and will lower the intensity of the light transmission through the light tube to the number boards.
It is up to you to determine if you want to paint the inside of the light tube and what works best for your chossen LED’S.
DCC Sound Installation
How many times have you struggled to get wires packed into the shell on a custom DCC install without the wires getting pinched or jammed into the drive train? You can forget about all that mess if you install your equipment as pictured. Wiring is separated from the drive components intentionally to prevent entanglement. The steel weights are narrowed to provide room for wires, and the LED lighting can be installed onto the frame weights or speaker box. The Proto 2000 shell drops into place if wired as pictured. Did I mention the frame is isolated from the electrical path unlike that of the Proto 2000 frame.
I have chosen to use the TCS WOW sound decoder. This decoder screws in place on the motor mount with no modifications.
You may need to cut (lower) the plastic motor mounting tabs for other decoder installations but you can use the provided mounting tray as a guide if you need to.
Purchase Options
Due to the nature of this conversion, some modelers may already have modified locomotive weights that fit their needs. For you, I offer the frame as a stand-alone item.
Modifying the stock Proto 2000 weight is not difficult but will require some hand tools. The example weights pictured were modified using only a hacksaw and file to illustrate that this can be accomplished without a milling machine. All the weights I have tested are drilled and tapped deep enough into the casting that you should not need to tap the weight mounting hole after modification.
Using a stock Proto 2000 weight modified as shown may allow you to use the stock light tube on one end of your locomotive and a speaker would fit on top of the short weight. While I have not tested the final weight of the locomotive in this configuration it should be close to, or heavier, than the 14oz. full kit weight.
What You Will Need To Complete The Conversion
- Proto 2000 GP7 or GP9 shell with the coupler mounting pocket hardware.
- A Kato donor locomotive, any Stewart/Kato FA or FB unit will work.
- Optionally, a Kato motor and a pair of Kato trucks with retainer clips and driveshafts.
What You Won't Need
- Proto 2000 cracked gear replacements!
- You won’t need to modify the electric pickup to have reliable performance.
- A milling machine to modify your Proto 2000 to accept a DCC decoder!
One Response
Sounds interesting. May have an application soon.