Another day and a bit more progress,

The new frames have now been tidied up to match the metal frame, then checked to ensure that the body fits on correctly. In doing so I have noticed another issue with the body retaining screws being directly behind the buffer beam (and as such will probably have to be removed to fit screw links...)

I have now almost finished the underside modifications, the Bachmann keeper plate has had the break gear / springs chopped off and sanded back to get a flush back and a 1mm overall width.

A plasticard keeper plate has been fabricated (2 parts of 40thou, the lower part with larger holes to match the raised boss on the casting).

The Bachmann gear cover was chopped off the original keeper plate and glued in place on the new plate (with a new plasticard side to replace the side that was originally covered by the spring details. This is now drying before I will glue the thinned down spring detail to the sides of the keeper plate.

Once everything is glued on, it screws to the model using the original Bachmann screws.

At some point I will be gluing pickups onto the top of the new keeper plate. If I was doing this again I would probably make the top layer of the plate out of pcb to make wiring pickups easier

One area that has been an issue is the mounts for the pony trucks, the glue isnt getting a good bond between the greasy hard plastic and the metal chassis block. I think drilling through the whole chassis block and bolting might be a good solution, though I think it best to wait and see if I manage to source a new pony truck first...

Photos:

The starting point, Bachmann chassis with P4 trailing/leading wheels and one driving axle fitted

Slimmed down springs/break gear

Body fitted to widened chassis

The underside showing the incomplete keeper plate, the step between the keeper plate and the outer frame is where the springs will be glued.

The finished keeper plate sans springs/breaks

The new frames from below.