Replacing the Motor in A Con-Cor Turbine/U50/C-855 Chassis – Additional

Following on from last week’s post about replacing the motor in a Con-Cor Turbine/U50/C-855 Chassis, which you can find here, I have a few updates to share with you.

This chassis has been around since 1973 and has undergone very little change.  However there have been a few, and the more I work with them the more I find.  One of my fellow modelers, Mr Mike Musick, who wrote the guest article about changing the wheels in these chassis, has discovered that the most recent version released under the Rail Baron label has a different motor cradle and the new Kato/Atlas motor will not fit.  You can find Mike’s guest post about the wheel sets here.

The problem with the cradle is solvable by removing the part which clashes with the motor.  Mike says ‘This plastic is hard and not trivial to work with, a Dremel with a small burr bit is about the only way to remove enough material.’  Below is Mike’s photo of a modified cradle.


Mike also goes on to say ‘When removing the old motor, be sure to note the location of the “white stripe” on one side of one magnet. This indicates motor polarity, and the new motor should be oriented with the white stripe in the same relative position. This is especially important if it is not going to be modified for DCC;as with DCC if you get it backwards you simply swap the orange and gray wires.

The original motor in mine came with a 0.010″ shim in the motor cradle. So I swapped it out for an 0.020″ shim, which turned out to not be enough, it should be a total of 0.030″.’

The shim raises the motor as discussed in last week’s post, however too much will cause the gears to bind.

With the C-855 extended chassis Mike has also experimented with not gluing the cup gear extenders, shown below, into the cup gears.  This ‘in Mike’s words’ ‘lets the adapter cup gears “float”, which turns them into sort of a constant-velocity joint and may also influence the noise by reducing gear pressure’.

C-855 Chassis Extenders 11

These small changes can greatly affect the running of the locomotive  by improving noise reduction and smoothness of the motor.

Bob’s three C-855s, from last week’s post, have now all had their motors swapped out for Kato Atlas Motors and I was able to catch them this weekend running through Solent Summit station.  I haven’t added any sound to the video so you can hear, or rather not hear, the motors.

Next week’s post will be on Boxing Day here in the UK so it will be nice and short but for now I would like to wish everybody a Merry Christmas.