Graham Farish Class 91 Split Chassis DCC Conversion

Mistakes may damage your locomotive, controller or other accessories. Use a multimeter to make absolutely sure you have completely isolated the motor from the track before testing. Always use the Programming Track for testing. Our guides are provided for reference only, and you proceed entirely at your own risk. Unsure about something - try our DCC Conversion Service instead.

This guide covers the Chinese split chassis conversion method for the Graham Farish Class 91 electric locos including:

• Class 91 91004 'Grantham' GNER Blue (371-801)
• Class 91 91021 'Archbishop Thomas Cranmer' GNER Blue (371-802)
• Class 91 91026 'York Minster' GNER Blue (371-800)

The conversion requires part of the chassis milling away to isolate the motor from the track power, and also part removing to make room for the decoder. If you have a small enough decoder, it is possible to fit it diagonally in the blunt end of the loco.

Step 1 - Remove body

Remove the body by pulling gently upwards.

Step 2 - Disassemble

Remove plastic piece attached to the bottom side of the chassis by removing the screw. Undo the two screws that are holding the two halves of the chassis together. Take out the plastic pieces that pass through, as well as the two circular spacers and the rectangular spacer also.

Take out the two bogies, and the motor.

Step 3 - Mill the chassis

Using a file or Dremmel style tool, remove the indicated metal from each side of the chassis where the motor contacts touch. You can check if you've removed enough material by popping the motor back in temporarily, and using a multimeter to check there is no continuity between the metal of the chassis and the motor contact.

Step 4 - Make space for the decoder

Mill out approximately 2mm from the top side of each half of the chassis, depending on how thick the decoder is that you are using. When seated, the decoder should not protrude beyond the 'bumps' that the inside of the body roof sits on.

Step 5 - Prepare the track pickups

Using a sharp blade, scrape away the black paint from underneath where the chassis screws and plastic square nut sit.

Step 6 - Reassemble the chassis

Reassemble the chassis by replacing the plastic spacers, motor and bogies. The easiest way to do this, is to place all components into one half of the chassis, and then place the other half directly on top.

Step 7 - Connect the decoder

Place the decoder in the milled out area, making sure it is completely insulated from the chassis using tape or your other preferred method.

Solder the grey and orange (motor) wires from the decoder to the pickups on either side of the motor. Again, check there is no continuity between these two wires and the chassis.

Strip about 5mm of wire from the end of the red and black (track pickup) wires and tin them with solder. Loosen one of the screws that hold the chassis together, and trap one of the tinned wires against the chassis at either side. Check you now have continuity between the rails/wheels and the red/black wires.

Step 8 - Test

Place the loco on your programming check and check you can read the loco ID and that it responds correctly to commands.

Step 9 - Refit body

Refit the body, ensuring it is completely pressed down. If it cannot go down all the way, check that you have milled enough space from the top of the chassis to accomodate the decoder. Refit the bottom plastic trim and you are done!

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