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BLOG: 4-SUB revival

Photo: On the workbench - from left: a DC Kits 4-EPB driving coach at the start of its revival, the restored Bulleid 2-EPB and the first driving car for the 4-SUB.


Regular readers of Hornby Magazine will have seen in the latest Staff Projects section that I have been working restoring a trio of kit built Electric Multiple Units (EMUs) to enter service on Twelve Trees Junction. All were originally built as analogue units for Bay Street Shed Mk 11, but for operation on Twelve Trees they required decoders installing as well as extra pick ups to make them reliable for exhibition operation. At least two of them will be joining the fleet for Twelve Trees next outing at the Basingstoke Model Railway Exhibition on March 10/11 2018.

First up was the Bulleid 2-EPB which I built from a No Nonsense Kits kit – a great looking unit which is somewhat different to the BR period stock – you can read more about that in Staff Projects in HM128. Next in line is 4-SUB which was built for the magazine back in 2008 for a pair of features. It hasn’t been in service for several years, but I have been determined to set that straight and bring the model back into working order – and with a few extra finishing touches too.

The 4-SUB looks much better for the additional of stencil route codes.

The first job was a simple one – adding stencil head codes to each end. These have been applied from the Hornby self adhesive sheets supplied with the 2-BIL and 2-HAL units and they make the world of difference to the front end of the unit.

Next was the big job – preparing the unit for digital control. This unit uses a pair of Tenshodo motor bogies (one at each end) and like the Black Beetle they suffer from poor electrical continuity when they aren’t pair with a second bogie for pick ups. As with the Bulleid 2-EPB, DCC Concepts pick ups have been added to the rear bogie of each driving coach which were then wired through to connect to the pick ups from the motor bogie.

Adding pick ups to the trailing bogie makes the motor bogie much more reliable.

A close up of the DCC Concepts pick ups on the 4-SUB. As an experiment one has been fitted with a supplied screw while the other is glued in place. Both methods work equally well.

With all the wires linked through, and the motor bogie modified so that the track pick ups are separate to the motor connections, DCC Concepts 8-pin harness Nano decoders were connected by cutting the plug off and connecting the track connections to the black and red wires and the motor connections to the orange and grey wires. To complete the unit the other end received the same treatment, but with the motor wires connected to the opposite sides so that both power cars drive in the same direction.

The Tenshodo motor bogie has had the track and motor connections separated and then wired for the addition of a decoder.

New holes in the floor allow the wires from the motor bogie to pass through to the interior.

The DCC Concepts Nano decoder wired in together with a ‘stay alive’ capacitor on the right.

One final job for now has been to change the coupling system. Originally the unit was equipped with Kadee No. 5 couplings which left an oversize gap between the coaches. All have now been replaced with Hornby small tension lock couplings after discovering that the 3mm drill that I already had in the Dremel made exactly the right size whole in the bogie stretcher to accommodate the coupling tails. The coupling were pushed through the holes and then glued in place with superglue.

Closer coupling thanks to have the right drill bit in the Dremel and tension lock couplings.

Apart from final tidying up of a couple of small paint chips and replacement of the guard irons the 4-SUB is now pretty much ready for testing and to enter service on Twelve Trees, but I do still plan to install the rest of the interior in the coming weeks prior to the layout’s next outing at the Basingstoke Model Railway Exhibition on March 10/11. However, I’m now digging into the next project which I am aiming to have ready for the same show – an Ayjay Models Tin-HAL two-car unit which will run on a Hornby 2-HAL chassis. Watch this space for more on these rolling stock developments.

I hope you enjoyed this latest post and if you have anything you would like to comment on, drop us a line to

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