The Chassis has to be modified to accept the New Bottom Plate that you have just set aside. Remove the weight attached to the top of the Chassis. The Chassis profile is shown in Appendix C. The drawings are provided in two forms; first in the form you find them. These views may have cut lines drawn on them. The second view, is how the part will look after the cuts have been made. Remember to sand or file each of the cut surfaces. The cuts can be done in the same manner that we cut styrene; i.e., score the surface deeply with a razor saw or hobby knife and bend the plastic away from the cut until it breaks, then sand or file.

The first modification to be made is to provide room in the sides of the Chassis for the new axles and electrical pickups. The electrical pickups currently mounted in your locomotive are one of two types: either brass wipers or small brass plungers. In either case, they should be removed. The brass wipers will come out with the old motor. There is usually some hard yellowish adhesive used to hold the wipers to the side of the Chassis, also there may be a couple of cast-in wedges to hold the wipers in place. Detach the hard cement with a hobby knife. Remove the old motor and wipers. If your loco has plunger-type pickups, these can be removed with a very small Phillips screwdriver.

The Chassis sides have rails above the shaped indentations, slots, and raised sections. The cut is made just below the rails. The cut proceeds to the rear of the loco to the plate that carries the raised brake cylinder. Measure in 3/4" from the rear indentation to find the diagonal cut line (see Appendix C). This will provide all the room needed for the new axles and wheel pickup contacts.

The brake shoes provided are a nice detail and can be retained or left off. If you wish to retain the brake shoes see Appendix F. The section just cut away from the Chassis also carried the brake shoes. By cutting a small section away, each brake shoe will have a square base to be glued to the aluminum frame (see Appendix F). The brake shoe assemblies can be removed from the Chassis, the protrusions on the backs of the base cut and sanded flat, then cemented to the new aluminum frame in their original positions.

The interior of the Chassis must be cleared out to permit the space needed for the new motor. First, remove the old motor by removing any motor mounts that are screwed into the Chassis. Please notice the wires (usually pink) from the two spring followers, do not cut these wires, they are to the sound system's trigger or switch. This trigger can also be used with many after market sound units. Next remove the gears by punching the pins from the side of the Chassis, once they are protruding from the opposite side pull them through

with a pair of pliers. There are usually two or three shafts each with a cluster gear internally. Once these items have been removed your Chassis will resemble the drawings in Appendices D or E. Inside the Chassis, there are two or three gear shaft mounts, which need to be removed. It is difficult to show this in the drawings.

The motor in the BBT Drive is a tight fit in the Chassis, so much so, that it can force the existing sides out far enough to touch the backs of the rear and center drivers. Therefore the next steps are to provide enough clearence for the motor without totally destroying the Chassis. The rivet details that are blackened in Appendix C should be shaved off and the same for the spring relief behind the second driver.

Appendix D illustrates the Chassis' top view. The cut lines are shown in the upper view and the resulting relief to the Chassis is shown in the lower illustration.

Appendix E illustrates the Chassis' bottom view. Again the cut lines are shown in the upper view and the results of the cuts are shown in the lower illustration.