Upgrade Arnold Ee 3/3

to 12V coreless motor

Fits Arnold art. 0104, 0109, 0160, 0161, 0215, 2420, 2421, 2422, 2423, 2424, 2425, 2426, 2427, 2428, 2431, 8620 and similar models (open your model to check compatibility).

What you need for conversion set

- The model and upgrade kit

- Small flat screwdriver

- Soldering iron 15W/25W

- A small file

- Epoxy glue

- Generic modelling tools

Installation time: Around 40 minutes

Difficulty: Bit fiddly, but not too hard.

Contents of the kit


Question? Just reach out!


Remove the two screws on the bottom of the model and you can easily take the whole thing apart.


If you do the filing (see following comment), cover the gears with tape, so the residue of the metal doesn’t go into the gears.

You can file the pilar a little bit to create a little more space for the motor, to give the wires more space. But before you do this, see if you are happy with it the way the motor fits.


This is the electronics board. Remove the parts marked, to make place for the motor. Use a sharp, fine cutter for this or a sharp knife.



The tray will fit precisely in place when you have the electronics board fitted. For your convenience, the indicated part touches the metal support. Glue the casing in place with using a tiny bit of epoxy glue. I used 90 second drying time glue.



Using the epoxy glue again, glue the motor in place. Check that the worm is centred in the box that is surrounding it. When it’s centred, it will naturally move freely.


Solder the wires to the contacts as shown and you’re done. Please note the right wire colour to the right contact. If you swap these around, the model will drive in the opposite direction of all your other models.

Test fit the casing.  Check if there are no remains of the print supports on the location indicated. If there is, the motor will not be flat and the worm will not touch the gear. If the motor is not laying flat, use a fine file to clean this part up. It doesn’t matter if you file too much, this part is only essential for positioning the tray.

First glue the brass adapter in the worm, using Loctite or Granville Bearing Fit & Studlock. Superglue can be used, but the problem is that you have to be very fast and the glue may set before you have everything in place. Then place the worm/adapter assembly on the motor shaft. Leave about 2.5 mm between motor end and worm. Check on model to see if it is positioned straight above the gear. It might be that the assembly fits with friction, so you don’t have to glue it. You can test fit without the electronics board present for a better view.

Test it and when it’s all running perfectly, place the housing again. If you want to convert it to DCC, the sweet settings for several brands of decoders are explained on this page (click link).

And one more model has been brought back to the future!