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  • Andrew Fitz

How to Re-Motor HO Scale Roundhouse Climax & Box Cab Locos

Updated: Oct 28, 2020

In the late 1980’s Roundhouse introduced a Series of powered HO Scale 8-Wheel Drive Climax Logging Steam, Box Cab Diesel and Box Cab Diesel Track Cleaner Locomotive Kits. In the tradition of their extraordinarily successful and prized 2-Truck and 3-Truck Shay Locomotive Kits, this new series also used slide-on plastic transmission parts and gears. Available on our website

Sadly, as became notorious with the Roundhouse Shays, these plastic parts were 100% doomed to early, or eventual, failure resulting in dead locomotives. Northwest Short Line of Montana came to the rescue of the Roundhouse Shays by producing extremely high quality and long-lasting Brass and Delrin replacement gears and linkages. Thankfully, these replacements remain in production to this day and are available on our website. Sadly, no similar replacements have ever been offered for the Roundhouse Climax and Box Cabs.

Some time ago we investigated the Roundhouse Climax/Box Cab issue on the web and, though info and comments are plentiful, found little that was positive or helpful. We decided to come up with our own modification. Though Northwest Short Line does not make specific replacement gears and linkages for the Roundhouse Climax or Box Cab they do make these wonderful, self-contained power trucks called Stanton Drives. Use of Stanton Drives for the Roundhouse Climax and Box Cab IS discussed on the web typically described as being “complex”, “difficult” and/or “too expensive”. Having used Stantons in applications to power Custom Jordan Mack Railcars and other originally non-powered loco kits we are very familiar with their capabilities and dove into applying them, and our experience, into coming up with a Roundhouse Climax/Box Cab application. Contrary to web banter, our result is surprisingly elegant, simple, and inexpensive while greatly improving performance at the same time.

What follows are step by step instructions to modify your own HO Scale Roundhouse Climax Steamer or Box Cab Diesel. There are few extra parts or tools needed (See List) other than the 1210 39279-4 Stanton Drive available on our website or directly from Northwest Short Line. (Caveat: If ordered from NWSL there may be a significant waiting period as they are built to order.)

Tools and Parts Needed:

Electric Drill

Small Screwdriver

1/16” Drill Bit

1/8” Drill Bit

7/64” Drill Bit

(2) 1/16 Diameter x 7mm Long Self-Tapping Screws

PERMATEX Threadlocker or Super Glue and Walther’s GOO (Optional)


Remove the original motor and all associated components except the central gear assembly. It stays for cosmetic purposes.


Remove the Truck assembly from the side of the frame opposite of where the original motor would be.


Set the frame down in front of you with the original motor location and remaining Truck on the left. Notice two pre-drilled holes at the top and bottom right of the frame. Draw a line across the frame bottom between these two holes. Mark the center point on this line and drill a 7/64” hole. Drill a second 7/64” hole for the wire run 5mm to the left of the first hole.


Remove the bottom plastic cover from the still-mounted-Truck, remove the worm gear and replace the cover. DO NOT remove this Truck. It stays where it is with no further modification.


Detach the two Side Frames from the removed Truck. They are only tension mounted. File or grind down the central elements and retaining posts on each Side Frame until only 3mm remains. (Notice the pencil mark on the central element in the image below.) Ensure that the remainder is flat and equal on all sides. This WILL take some time. (See other images for reference.)


Notice a peak shaped element in the center of each Side Frame. Using a 1/8” Drill Bit, drill a hole at the top center of these peak shaped elements just under the top crossbar.


Line up the Truck Side Frame as closely as possible with the wheels on one side of the Stanton Drive and hold it there. Stick your drill bit or similar through the hole that you drilled in the Side Frame and mark the location on the Stanton Drive. Remove the Side Frame, make sure that your mark is centered, and use a 1/16” Drill Bit to drill a 1/8” deep hole in the Stanton Drive where marked. There is only plastic in this location on the Stanton. Take a 7mm long self-tapping screw that will fit in the hole and attach the Side Frame to the Stanton Drive. Repeat for the other Side Frame. (Optional: Making sure that the Side Frame is mounted squarely on the Stanton, for extra support put a small amount of Walther’s GOO (Availible on our website) along the top seam and allow to dry overnight.)


Run the wires through the second hole that you drilled in STEP 3 and mount the Stanton Drive in the first hole that you drilled in STEP 3 using the washers and two nuts included with the Stanton. (Optional: Apply a drop of PERMATEX Threadlocker or Super Glue to the top of the screw and top nut for extra security.)


Admire your work and track test your loco. Like any new motorized locomotive it will need to be broken in for an hour or so at various speeds to perform at its best. You will discover it is incredibly quiet and smooth at all speeds including, if you wish, much higher speeds than the original. Enjoy!

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