A couple of my operators have several of these between them, and they vary from being pretty decent to downright awful runners. Typical Athearn RTR inconsistency.
A recurring problem with these units is a tendency to be highly derailment prone despite all the wheelsets being in gauge. It's sometimes necessary to disassemble the trucks to inspect all the moving parts, and to ensure the axles have sufficient sideways play to properly negotiate curves. One SD38 that was test run on my layout had problems on 42" plus radius curves, another SD40 is unreliable anywhere but on straight track. We know these issues are locomotive related and not based on the track, as nothing else derails where these units do and there are no problems otherwise with the track (uneven installation rail kinks, etc.).
One SD40 is very stiff, which overworks the motor and decoder to the point it's burned up two decoders. The owner isn't sure the problem lies more with the motor or elsewhere in the drive, but it gets hot when running and has resisted efforts to tune it up so far.
Based on what I've seen, I'd advise that you test run your prospective purchase if at all possible, and make sure it runs well on curves. If you can't, at least be prepared to do some disassembly and tune-up. I have a few such mechanisms based on older Athearn blue box units with a lot of tune-up and remotoring work invested, and they all run fine and stay on the track. I suspect the RTR models would be just as good with the same effort invested.
Rob Spangler
I have a few of the RTR SD40/45 family of locos. They are all typical Athearn runners, which is to say they run okay but not great. It's generally a good idea to give them a basic tuneup before you put them on the layout. That tuneup will usually quiet them down and smooth them out, although sometimes you'll run across one that needs more than just the basics.
I haven't bothered with sound or additional lighting functions, because I view them as fleet locos. For that reason I usually just plug in a less-expensive fleet decoder into the stock Athearn board and call it a day. BTW, I've never had any issues with those stock Athearn boards.
Having said that, there's plenty of room in the shell if you do want to add sound, more lighting functions, etc. In that case, removing the stock board would probably be the way to go.
Texasboy84 - Welcome to trains.com!
Darren (BLHS & CRRM Lifetime Member)
Delaware and Hudson Virtual Museum (DHVM), Railroad Adventures (RRAdventures)
My Blog
I am just getting back into the hobby after being away for almost 10 years, and am looking at getting my first new engines in that time. A lot has changed in the hobby in that time. Does anyone here have any experience with the RTR Athearn locomotives of the SD 40/45 family? I am considering getting a few of them, in SP livery, but would like to know how the wiring is set up for the lights. I want to be able to set up on DCC to have the typical gyralight they had on the christmas tree light package. Is this possible by just plugging into the dummy plug on the existing board? Or does it require pulling the existing board out, and hard wiring the decoder in? I have seen on other message boards that there seems to have been an inconsistancy in the reliability of the existing athearn board while on dcc. Is it just better to remove it anyway and potentially save headaches later?
Also, how much room is inside the shell to fit a sound decoder and speaker inside?
Thanks