Need help to disassemble an Athearn SD-9

[Anonymous]

As a retiree just getting into HO, I'm looking for some help in disassembling an Athearn SD-9 loco. Specifically, how do you remove the motor and the trucks.

It looks like the motor mounting pad is a press fit into the underframe, but I don't want to break anything using brute force. I have the original Athearn parts breakdown sheet as a guide.

A high school buddy, who has become a disenchanted model railroader, generously donated two of his Athearn locos to my cause. I am going to install DCC encoders, but wanted to give both locos a good cleaning and lube first.

I'm usually very good at mechanical assembly/disassembly, but this one has me stumped.

Thanks for any help you can provide.

[cspmo]

QUOTE: It looks like the motor mounting pad is a press fit into the underframe

You are correct, they are.

[cwclark]

you can still remove the motor from the frame mount by gently prying it back and forth until the rubber tabs come loose from the holes in the frame (be gentle...too much force can shear the rubber tabs right off) ...once you remount it, you can glue it back in place by applying an adhesive to the tabs.....i don't do DCC but have read that the athearn locomotives must be insulated from the frame with electrical tape..i'd check into that before installing the decoder...

[mcouvillion]

To remove the motor, especially if this is an older Athearn, use a small screwdriver to gently push on the motor mount tabs from the underside of the frame. If the mounts are very old, they are probably brittle and will break regardless of the care you take. They should be pliable. Your hobby shop should have replacements in stock.

To remove the trucks, disconnect the drive shaft from the universal joint (if the motor isn't already out) and then take a small screwdriver to the side of the top of the gear tower next to the worm gear. Spread it gently to the side and the worm gear cover should pop off. Remove the worm gear (and its bushings) and place aside. The truck should drop out. To disassemble the truck, again use a small screwdriver to remove the clip along the bottom of the assembly between the wheels (the whole bottom of the truck). You might have to pry gently between each pair of axles on one side, since there are two catches on each side of the cover. Remove the cover. On the tapered end of the top of the truck, there will be a small cover plate of similar design. Remove it too. Remove the axles and your truck will easily come apart. Clean, lube, gauge the wheels, and re-assemble in reverse order.

Mark C.

[Anonymous]

Thanks for all the replies! All the information is helpful and I have successfully disassembled the motor and the trucks. Clever design, but obviously made with quick assembly in mind, rather than periodic maintenance.

I was aware of the motor grounding problem with DCC and will check all that out before applying power.

[ckape]

The power from the motor to frame goes through the copper pad on the bottom of the motor. To isolate the motor just put a strip of electrical tape on the frame beneath the motor.

Another suggestion is that if you've got an open-frame motor you really should look into getting that replaced with a can motor, since it'll use significantly less power than the open-frame model.

[ericsp]

QUOTE: Originally posted by hanktesta

Thanks for all the replies! All the information is helpful and I have successfully disassembled the motor and the trucks. Clever design, but obviously made with quick assembly in mind, rather than periodic maintenance.

I was aware of the motor grounding problem with DCC and will check all that out before applying power.

I don't remember what issue it was in, however Model Railroader had a small article in one the last few issues about installing DCC in Athearn locomotives.

[Anonymous]

Thanks ericsp,

Looks like it was the October 2004 issue.

How quickly we forget!

Now if I could just find the issue.....

[Anonymous]

Thanks ckape,

Any suggestion on where to look for a replacement motor?