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Bachmann F7 Diesel Project

Started by jonathan, July 14, 2020, 01:53:50 PM

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Taking a break from scenery for a while.  Felt it was time for yet another locomotive project.

This is an F-7A, DCC ready loco.  The guts are the same as Bachmann GP units. The photos should be helpful for those curious about the inner workings.  I've installed DCC and sound in this type of loco before... one of the easier sound installs.  This one is going to stay DC for my home layout.

Took about 5 minutes to disassemble, with the four tools in the photo:

DSC_0406_01 by Jon Vogel, on Flickr

I started with the trucks:  inspecting the gears, cleaning out excess lubricant, adjusting pick up brushes if necessary, whatever is needed.  These trucks were in good shape.  I only needed to adjust one pick up brush.

When installing the truck, I find it's easier to leave-off the truck frame until the truck is back in place.  I feed the wires through their holes before putting the drive axle back in the flywheel. Do this SLOWLY, as the wires are delicate:

DSC_0407_01 by Jon Vogel, on Flickr

The new Kadee coupler is visible. You can see the shank is shiny from where I filed just a bit from the shank's top and bottom.  This makes them fit into the Bachmann coupler boxes.

Once the wires are pulled through and the drive axle back in place, it's time to line up the truck's screw hole with the frame hole and put in the small screw. Don't overtighten. This should be a bit loose for proper play in the truck:

DSC_0408 by Jon Vogel, on Flickr

Now the trucks' wires can be fitted back on the pcb.  Red goes on the right.  The little black plastic tabs hold the wires in place after the wires are threaded:

DSC_0409 by Jon Vogel, on Flickr

Little tab back in place:

DSC_0410 by Jon Vogel, on Flickr

This is the receptacle for installing DCC, if so desired.  I'm leaving in the jumper plug for this project:

DSC_0411_01 by Jon Vogel, on Flickr

So far, I've drilled 40 holes in the shell, assigned a loco number, changed out the couplers, repainted the crew, and started putting in a rough coupler lift bar. This loco won't be as highly detailed as my sound-installed loco:

DSC_0413 by Jon Vogel, on Flickr

Some lift rings:

DSC_0414_01 by Jon Vogel, on Flickr

Also weathered the truck frames before pressing onto the trucks:

DSC_0416_01 by Jon Vogel, on Flickr

Lots of work left to do.  Will post again when I've made more progress.




Very nice. Airbrush weathering or powders? Both?




 A little bit of trivia for B&O fans. In the pre 1957 3 digit numbering scheme, even numbers were temporary numbers.  As delivered, B&O cab type units had odd numbers, with most having a letter suffix. For example, an A_B_B_A set numbered 937 would have individual units numbered 937, 937x, 937ax, and 937a. They would run together as a set. the x units would be the two B units, and the 937a would be the other A unit. If the set were broken up for some reason, the unit with the A suffix would be temporarily renumbered to the the next higher number, in this case 938.  This was accomplished by merely changing the numbers in the number boards. One F units and GP7s and GP9s, these number boards were fitted in a removable light box, and the individual numbers slid into slots in front of the lamps in the box, and B&O equipped the affected units with an extra set of boards for this temporary renumbering. Having been in the noses of numerous GP7s and GP9s, I can tell you it would have been a 5-10 minute job to change the numbers if the appropriate boards were on hand.

The 1957 renumbering whereby all diesels got 4 digit numbers and the few remaining steamers got 3 digit numbers put an end to this practice, and all A suffixed cab units got permanent even numbers.
Jeffery S Ward Sr
Pittsburgh, PA


Thanks, guys.

Sid, I use only weathering powders... so I can wash it off, if I don't like the result.

Jward, thanks for the numbering trivia.  I would go down a rabbit hole for weeks, if I tried to be true to the B&O system of diesel numbering.  Thankfully, I can find photos of old equipment and at least be reasonably confident that a certain number actually existed.  

Wish I could find photos of the BACK of the F-7.  

The pcb has tabs for a reverse light, and the resistor is already on the board. Sooooo...

DSC_0419_01 by Jon Vogel, on Flickr

Don't know if the B&O actually put reverse lights on their F units, or how they would be mounted, but I did it anyway. The light cover is a Kadee spacer sitting in my parts box.  I filed down a warm/white LED to fit inside.

The board is a mystery.  Through testing I discovered the reverse light is always on, in forward and reverse.  I'm just an electrical novice, so I'm not going to attempt to noodle out that one.

I've added all the details I care to.  There's always more, just don't feel like drilling any more holes.

DSC_0420 by Jon Vogel, on Flickr

When the glue dries, I'll wash the shell, paint the details, add the glazing,  weather, and we're done.




You can make the rear light directional if you use some solder wick to remove the solder bridges between pins 1, 2 & 8 on the dummy plug. Run a wire between pins 1 & 8 and a 1N400x diode between pins 2 & 8. Check to make sure the diode is the right way around to let the rear light come on in reverse before soldeing everything in place.

If at first you don't succeed, throw it in the spare parts box.



DSC_0422 by Jon Vogel, on Flickr

Reverse light:

DSC_0421_01 by Jon Vogel, on Flickr

Runs very well, and I haven't even cleaned the wheels, yet.

Len, I really appreciate the circuit instructions.  Makes me wonder, though... would a diode work, if I just installed it on one of the wires I have now?

I really should get off my duff, and move to DCC on my home layout.  Then everything would work the way it's suppose to.  Don't know why I keep procrastinating.  Everything I own is DCC ready, except the brassies.




Yes, adding the diode to one of the wires would work too.

If at first you don't succeed, throw it in the spare parts box.


That looks very nice Jonathan. I have weathered a couple box cars, but can't bring myself to start weathering my Rapido Locomotives. I know i need too, i will wait till i have a bit more courage.