Nick Dunhill
Western Thunderer
I have fitted a Premier Components PC522 motor and gearbox into an Heljan A4 chassis.

It isn't that bad of a model, but it has very limited pulling power off the shelf. I took out the (huge) Heljan motor and ran it at full chat. I could easily stop the motor turning by grabbing the flywheel. The motor gets very sparky. I took out the rear wheelset and discovered that the axle is 5/32'', and K&S do a tube that is 5/32'' ID and 3/16'' OD. I cut a 13 mm length of tube and drilled a 2 mm hole in it 4 mm from one end. This serves as a sleave for the axle and gearbox which of course is designed to accept a 3/16'' axle.

This will allowed me to slide the axle through the bearings and gearbox, reattach the wheels, and Bob's yer uncle.

I did of course have to attack the 3 components of the chassis with a die grinder and a saw to create the space for the gearbox and motor. It does appear to work nicely though. The A4 will now pull our Mini.

It isn't that bad of a model, but it has very limited pulling power off the shelf. I took out the (huge) Heljan motor and ran it at full chat. I could easily stop the motor turning by grabbing the flywheel. The motor gets very sparky. I took out the rear wheelset and discovered that the axle is 5/32'', and K&S do a tube that is 5/32'' ID and 3/16'' OD. I cut a 13 mm length of tube and drilled a 2 mm hole in it 4 mm from one end. This serves as a sleave for the axle and gearbox which of course is designed to accept a 3/16'' axle.

This will allowed me to slide the axle through the bearings and gearbox, reattach the wheels, and Bob's yer uncle.

I did of course have to attack the 3 components of the chassis with a die grinder and a saw to create the space for the gearbox and motor. It does appear to work nicely though. The A4 will now pull our Mini.
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