Graham Farish Class 170 Turbostar DMU 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 170 diesel multiple units including:

• Class 170 DMU in Cross Country livery (371-431)
• Class 170 DMU in Cross Country livery (371-431A)
• Class 170 DMU in London Midland livery (371-432)
• Class 170 DMU in London Midland livery (371-432A)
• Class 170 DMU in Scotrail Saltaire livery (371-433)
• Class 170 DMU in Central Trains livery (371-434)

The conversion requires part of the chassis milling away to isolate the motor from the track power. Depending on the decoder thickness, you may also need to mill out part of the top surface of the chassis block so that the body sits correctly. This example show the 3-car version of the model, the centre car is powered.

Step 1 - Remove body

Remove the centre car's body by gently pulling upwards.

Step 2 - Remove capacitor

Remove the capacitor bridging the two halves of the chassis by removing the two small screws. This component isn't needed when running under DCC.

Step 3 - Remove underfloor detail

Remove the underfloor detailing piece by turning the unit upside down and removing the two screws from the bottom.

Step 4 - Split the chassis in two

Unscrew both screws holding the two chassis halves together. They screw into plastic nuts. Lay the chassis on its side.

Gently prise the upper half apart, and carefully remove all of the plastic spacers, and then the two bogies and the drive shafts.

Step 5 - Prepare the motor

Remove the motor and solder a grey wire to one of the contacts, and an orange wire to the other.

Step 6 - Remove part of the chassis

Using a Dremmel or a file, remove the part of chassis that was previously contacting the motor. This enables us to insert a DCC decoder between the track power pickup and the motor. Refer to the main Chinese Split Chassis Guide for a detailed diagram of the sections you need to remove.

Step 7 - Put the chassis back together

Refit the motor, then check there is no continuity between the motor contacts (i.e. grey and orange wires) and the chassis.

With a knife blade or similar, scrape away the black coating from where one of the screws will meet the chassis. As you put the two halves back together, trap a tinned red and black wire at either side so they make an electrical contact with the chassis. These will be the track power feeds.

Step 8 - Fit decoder

There is enough space between the top of chassis block and the body roof to fit the decoder, providing it is thin enough. Here we have used a Doehler & Haass PD10MU-3 which is very thin, and fits perfectly. If you are using a thicker decoder, you will need to mill out some of the top of the chassis block. An example of this is our Class 91 GNER conversion.

Step 9 - Test

Check the motor contacts (orange/grey wires) have no continuity with the track pickups (red/black) or any part of the chassis block using a multimeter. Once you are happy the conversion is good, put it on your test track and read the loco ID. It should return the default value of 3, and when it does your conversion is complete.

Our DCC Conversion Service