Converting a Bachmann BR 03 Shunter chassis to fit inside a Craftsman BR 07 shunter

The running quality of my locos is important to me. Irrelevant of how well made they are or how detailed, if they cannot run along a piece of track smoothly or cross a point without stalling, then the loco is of little use to me.

The long suffering Craftsman BR 07

My BR Class 07 Shunter is one such loco that looks much better than it runs. This Craftsman kit was purchased partly completed in 2003. One of the areas completed was the chassis, which was quite jerky and the rods appeared to be binding. I decided to deconstruct the chassis and start again.

I rebuilt the chassis with a new set of wheels and a new Mashima can-motor. I spent a very long time making sure that the chassis was set up properly so it would run smoothly. This was all done on a straight test track. I didn’t realise that the engine would not enjoy going round curves or crossing points.

I persevered, redesigning the pick-up arrangement on the wheels. I was also trying desperately to find a method of keeping the motor from rocking backwards and forwards, which made the fly-wheel skim the inside of the bonnet. My attempts at stabilising the motor eventually led to the DCC decoder blowing up, and the 07 quickly went back into storage (it was that or out the window).

Craftsman chassis (left) and Bachmann 03 chassis (right)

After purchasing a couple of the new Bachmann Class 03 Shunters, I started to wonder whether one could be adapted to replace the Craftsman chassis. I did some quick measurements and decided it was worth a go.

Body modifications

The first thing I did was widen the opening for the chassis and cut away some areas inside the 07’s body cavity. This modification also required removing the floor of the cab and cutting away the control panel (no doubt much easier if the body has not been constructed). The opening into the rear bonnet also required opening up slightly for the DCC decoder harness.

It looked as if the 03’s chassis may actually fit inside the frames, but the chassis itself would require some modifications.

Chassis modifications

The main modification required was to remove the front end of the 03’s die-cast chassis. The length of this section of metal restricts the chassis from sitting where the 07’s wheel sets are prototypically positioned. My new hacksaw was used to cut away the front of the chassis, with some masking tape around the motor core; stopping any metal shavings getting inside.

Once this was finished I unscrewed the axle nearest the crank shaft from the coupled wheels and used a mini-saw to grind away the coupling rods so the cranks could be removed. At this stage I was a bit nervous whether the new chassis would still operate properly.

Reinvigorated

The new chassis runs very well and sits as low as I hoped it would. The 07 will now happily cross the point work of Brewery Pit. I next need to reattach some bits to the 07 that unfortunately fell off while I was accosting it with a mini-saw. I also want to see if I can fit some of the former chassis’s little details to the new one.

I am fully aware of the inaccuracies in the chassis including: the wheel sets not being entirely accurate, with a slightly different spoke arrangement; and the brakes being fitted the opposite way around, but (as I said at the start), if I have to compromise the accuracy of the loco to ensure I can actually run the darn thing, then so be it.

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