Installation instructions for the Yardbird D8120 Re-Motor kit
The D8120 remotor kit is designed to fit almost every application in which the original Mantua 5 pole, open frame motor is used. This is probably one of the easiest to install kits we've seen for these locos, other than the original motor. A flywheel application is not used with the D8120 in order to accommodate virtually all of the models with the least amount of modification. But, the powerful Mibuchi can motor delivers a steady, slower RPM speed that results in a smoother, more prototypical operation.
The following directions are somewhat generic in nature to fit all of the applications needed. If you have specific questions about a particular application, please look at our "Loco Specs" pages or contact us. You will need some basic tools such as a small screwdriver, flat file, soldering iron, electrical tape, etc.
1) Remove the boiler from the loco, being careful to watch for wires, etc. Also, on many smaller Mantua locos the steam chest may be free to slip off of the frame, so you will want to secure it by placing a small nut on the screw and cinch it down. Be careful here as the crosshead slide, valve gearing, or both will come loose if the steam chest is dislodged.
2) Unhook any wires from the existing motor, being careful to keep them them grouped how they are if there are more than one. In some cases, you may have to unsolder the wire going to the tender from the motor (normally the left side).
3) Turn the mechanism upside down and find the one screw that holds the motor in place. After locating it, carefully remove it and free the motor from the frame.
4) Check the drive gear to make sure it is in satisfactory condition (no excessive or uneven wear). It would be good to take a fairly stiff bristled brush and clean the teeth of the drive gear while turning the wheel.
5) Set the D8120 motor unit on the frame and check for fit. Insert the motor screw back into the hole and check how much it protrudes past the frame. There should be approximately 1/8th inch to screw into the new motor base. If there is less, you will need to obtain a longer screw in order to secure the new kit properly (be careful not to use a screw with more than 1/8th inch sticking out as it may go too far and touch the motor shaft).
6) Check the worm gear / drive gear clearance. The tolerance between the two gears should be minimum, so that you can just slightly move the drive wheel back and forth within the teeth of the worm gear.
- If it is too tight, take a small piece of cardstock (such as from a business card) and after making a hole in it for the screw, place it over the screw and between the motor mount and the frame. Recheck for tolerance.
- If it is too loose, place the motor unit on the flat file and carefully file the bottom of the mount to remove a slight amount of metal, rechecking the tolerance often.
- Be careful not to over-tighten the motor screw into the new base.
7) After you are satisfied with the fit, attach the loose wires to the small leads of the motor (I suggest soldering and insulating with tape or compound. The lead coming from the coal tender should be on the right (white dot by the motor post), and the lead coming from the other side of the motor (red dot by the motor post) would normally screw somewhere to the loco frame. (note: this would be different for DCC wiring - see the instruction sheet included with your DCC decoder)
8) We recommend that you bench test your loco frame to make sure all is well. Replace the boiler and anything else that was removed during the process.
This completes the installation of your new Yardbird D8120 remotor kit. Your loco should be ready to run and ENJOY!
We're interested in your comments and suggestions. If you would like to contact us concerning the Yardbird D8120 remotor kit, please do so by clicking here. Thanks for choosing Yardbird Classic Trains!