Bachmann class 47 replacement motor

[GWR-fan]

A few weeks ago I purchased a non runner Bachmann class 47 #32-800 from a well known store.  I thought it worthwhile to see if a simple fix or maybe something major to get my brain working.   Well,  the item arrived yesterday and after moving forward about 60 cms it stopped and tripped off my power supply.  After stripping the motor out and testing directly to the motor terminals,  sparks emitted from the commutator end and my power supply tripped again.    I suppose if I had the time and the money I could await a replacement motor from Bachmann Europe,  but I decided to look in my spares box.

 

I found a Hornby X9863 motor from a class 43.  This is a black motor with dual flywheels.  Comparing to the Bachmann Buhler motor,  the motor case length and width were the same and even the overall shaft length identical.  The Buhler motor clips into a saddle mount whereas the Hornby motor is screwed down with mounts at each corner.  After a little head scratching the Hornby motor mount pads were cut off and width trimmed slightly to fit inside the Bachmann chassis casting.  The original Bachmann saddle mount needs to be removed.   A 0.040" styrene mount pad was glued to replace the Bachmann saddle mount and the motor glued in position,  ensuring it was aligned both laterally and longitudinally.  When I went to hook up the driveshafts it became obvious that the shafts were slightly too short as the shaft recess in the Hornby drive coupling is deeper than the Bachmann coupling,  so the shaft could slide further  inside the coupling thus disconnecting the shaft from the bogie coupling.  Now in hindsight what I should have done is most likely moved the flywheel coupling each end of the motor further away from the motor casing,  thus reducing the distance to the bogie coupling to compensate for the deeper recess in the coupling,  however,  given the late hour and my need to get up very early the next morning I did not think of this.  What I did was by trial and error,  insert styrene shim pieces inside the motor coupling until I arrived at the correct size.  The bogies were then hooked up and the drive tested.  Only hiccup was reversing the motor wire terminals on the circuit board to achieve correct direction response and directional light function.  The loco runs beautifully.

 

Of cause,  a replacement Bachmann motor would have been nice but I did not have one in my spares box.  I feel the quality Hornby motor just as good (well maybe not as good as the original Buhler motor)  and with a little ingenuity I have rescued what would have been a pile of spare parts.

Edited June 25, 2020 by GWR-fan
Additional info

[GWR-fan]

Very odd.   Last night after seeing the motor sparking and tripping the power supply with power applied directly to the motor terminals,   I sprayed the commutator with electrical contact cleaner.  I dried it thoroughly and then retested the motor.  Same condition,  sparks and power tripping.   24 hours later with nothing to lose I tried power once again on the motor.  It works perfectly.