One of my locomotives, a RTR GP40-2, has had the usual noise issues. After doing some googling when I first got it I took steps to alleviate the problem and for the most part they worked, but recently the coffee grinder sound has returned although not as bad as the first time . I popped off the shell again and took a really close look at the motor and discovered that the armature seems to be occasionally rubbing against the magnets. When you grasp the motor between your thumb and forefinger you can actually feel the contact between them.
There’s the usual horizontal play with the motor shaft and a small vertical amount which I think is causing the problem. Loosening the mounting screws on the bottom of the motor has helped to a degree, but is there anything else that can be done to the motor?
If you still want to fix the motor, you can do it very easily if you have a Puller by NWSL. Take off one of the flywheels, slip one of the ends off the motor to get to the magnets, and take the magnets and gold housing off. Super-glue the magnets to the inside of the housing, and put the motor back together. It should fix the problem. A new motor with flywheels is easier, though.
Well Athearn customer service got back to me and there was no offer of a replacement, but they did suggest lubricating the motor bearings. I already did this previously, but I think I’ll be trying out Darth’s suggestion this weekend. I’ll probably also be checking into getting another motor in the near future if the repair job isn’t completely successful.
I have a RTR Athearn SD40 that had a bad motor, a very slow runner. I contacted Athearn about it and they had me send in the old motor and sent me a new one that worked properly.
Some cautions: before removing the magnet or the armature, place a “keeper” across the poles of the magnet. A flat piece of steel will do the trick. Athearn uses Alnico magnets, which will lose a significant amount of their magnetism if removed without a keeper. Using a glue will also cause a slight loss of magnetism, since it will slightly move the pole pieces away from the magnets. Magnetic force decreases as the cube of the distance from the source of the magnetic field.
I would strongly recommend replacing the motor. Repairing it would be more trouble than it’s worth. If you do still want to persist, if you can find some suitable neodymium (“rare earth”) magnets, you could replace the stock magnets altogether. I did it on an old Athearn all-metal RDC, and it worked wonders. Faster, stronger, lower current draw. The NdFeB magnets are the strongest known type of magnets. No “keeper” ever needed, don’t lose strength over time.
The vertical play in the motor can easily be causing your problem, it’s an indication of a worn motor bearing on that end. If that’s the case, the only viable solution is to replace the motor.
The thing is that I purchased the locomotive back in June and probably have put only about 10 hours of use on it since. I bought another Athearn GP40-2 this week and it’s almost as quiet as the several Atlas Silver Geeps that I have. I guess this is a good example of the varying quality issues with Athearn.
I’ll probably check into a replacement motor the next time I visit the LHS.
Really? I thought they were ceramic. I’ve got some Athearn Gold motors that I’ve taken apart probably a dozen times, and they’ve retained their full magnetism. The magnets are black in color and curve around the top and bottom of the armature, like in a can motor.
The old silver motor from Athearn did use a cheap AlNiCo magnet. I have one in my old Hustler, and it was easy to replace the old magnet with a stack of neodymium magnets. It really improved performance a lot.[:D]
Whoa, fellas. Before we start spending money or taking magnets out, try this simple fix:
1). Remove the shell and loosen the motor mount screws.
2). Run the loco up against a bumper post at full speed.
3). Carefully twist the motor ends made of black plastic one way, then the other. Try lifting a little and pushing down on these ends. What you are looking for is a “sweet spot” where the motor noise goes almost silent. This “sweet spot” means that the bearings and magnets are all perfectly aligned with the shaft. You can also tell by listening to the RPM’s increase and the motor takes on a higher pitch. If you really want to get technical, hook up an ammeter and you’ll see that the amps will drop in the “sweet spot”, and go up as the motor goes out of alignment.
4). Once you get the best results you can, stop the loco carefully so that you jar nothing loose.
5). Mix up some 5-minute epoxy.
6). Apply the epoxy liberally to the motor ends where they meet the gold center part. Obviously, do not get any in the moving parts, and do not glue the motor to the frame. Wait for the epoxy to fully set.
7). Carefully tighten the motor mount screws, but do not sock it down too tight. Finger tight is tight enough, IMHO. As long as one screw is solid, you should be fine. What you don’t want to do is to move the motor out of the new alignment.
8). Run the loco, and it should sound pretty sweet.
9). You can then try all the usual Athearn tricks to smooth out the drive train. Grease and oil gears, worms, bearings, etc. I also apply with a Q-tip some 2-26 electrical lubricant to the armatures. One can also try the “Jim Six Fix” where he cut off the rear 1/3rd of each motor brush. This reduced spring force on the armature and incre
Darth, I stand corrected. [:I] I was indeed thinking of the old open-frame motor. My comments are true, though, when referring to any of the old open-frame motors (of which I have a plethora).
Any motor with an Alnico magnet should have a “keeper” attached to the magnet before removing same.
Sorry to all for the mistake - I tend to think in terms of the old-time stuff, since most of my locomotives are old-technology.
If you need a new motor contact Robs. He makes the helix humpers they are a drop in replacement that uses the flywheels from your origional motor, I have about 12 of these and they are the best in my opinion