How to rewheel a Mantua diesel!

[Darth Santa Fe]

My Shark is from the earliest run (1953?), so there were screws instead of rivets. The rivets will have to be drilled out to remove the wheels from your truck, and then you'll have to use long screws and nuts to reassemble the truck. Or, if the rivets are still in decent shape, you can glue them back in place when you're done.

[bitlerisvj]

Hi, I just saw this and am really intrigued.  I have 3 A-Units and 1 B-Unit of these cast sharks.  I can see that it is pretty easy to replace the wheelsets on the power truck, but how did you remove the wheelsets from the dummy truck.  On mine, the sideframes are riveted together and hold the wheelsets captive.  Did you remove the rivets and replace with new ones?

Thanks and regards, Vic Bitleris

[Darth Santa Fe]

Got an old Mantua diesel you want to run, but a bad wheel or two are causing it to have an annoying wobble? Or maybe you want it to run through switches without losing power? Here's how to make it all better!

Mantua uses 40" wheels on their diesels with a 1/8" axle. For this conversion, I'll be using Precision Scale wheels because they were available. For anyone else, I would highly recommend using NWSL 37129-4 axles. The PSC wheels are great, but their axles are slightly larger than 3/32" (0.097"), making them very difficult to work with. NWSL axles are a true 3/32" diameter (0.093", it makes a huge difference!). 1/8" brass tubing, thin brass sheet, fine wire (I use 24 gauge), thin plastic bubble packaging, and Kadee centering springs are also needed.

I started by polishing the brass tube to a high shine. I then cut it to a 14mm length to press onto each axle.

Next was to remove a wheel to press the tubing on. The extra diameter of the PSC axles made this very difficult. They will probably be closer to a slip fit on NWSL axles, so tap a dent or two into the center of the tube to grab the axle if necessary.

I then removed the gear from the Mantua axle and pressed it onto the new one, and then pressed the wheel back on. An NMRA standards gauge was very helpful for this. The gear should be as well centered as possible.

I tested each axle after completion for free rolling and smooth running. Because the tubing was so tight on the PSC axles, the ends warped a tiny bit and had to be ground down to eliminate binding. Once every axle was spinning freely, I ran the whole engine on track to make sure all was working well. The rear truck grounded wheels go to the right rail, and the front truck to the left.

To improve electrical pickup, I decided to make wipers for the backs of the insulated wheels. Kadee centering springs work very well for this. They give enough tension for reliable conductivity without causing a lot of drag, they're easy to modify, and they're easy to solder.

To make the wipers, I cut the centering springs in half, bent the arms almost all the way back, and soldered the halves to a 4x35mm piece of brass sheet. The MU-1 truck is a little longer than the more common MU-2, so a 30mm length of brass should work better for those. There are little tabs above the arms which should be cut off for clearance (marked in the picture). I then soldered a wire to the center of the sheet to reach the motor (about 2" for the motor truck, and about 4" for the dummy truck. An extra inch or more may be necessary depening on what you have). To insulate the assemblies from the metal truck frame, I cut clear plastic bubble into sheets the same size as the wiper assemblies and super glued them to the bottom.

Once the glue was strong and dry, I super glued the wipers to the bottom of the trucks where they would contact the insulated wheels. I further adjusted the wiper arms for best electrical contact.

To connect the wires, I soldered the one from the motor truck directly to the brush contact for the left rail. I soldered a terminal to the other one and screwed it to the motor truck frame. Then I tested to make sure all wheels were providing good electrical pickup. Some running helps to get everything working just right.

Once all was working well, I reassembled the model.

My Mantua Sharknose is now a smoother and more reliable runner. Because there are no tires, some extra weight is needed to improve traction. If a lot of traction is needed, "Bullfrog Snot" can be used on a wheel or two, or a second power truck can be added.

This project applies to all MU-1 and MU-2 power trucks built by Mantua. The later MU-2 trucks made by Tyco and Roco (for Tyco) should also be compatible, but many of them use plastic construction that will require a little modification to work. This will not work on Tyco's "Power Torque" sidewinder trucks.