I have a Athearn RTR Dash 9 that needed a new motor, thing was just way to slow. I got the engine new and ran the heck out of it for about 4 years. When I replaced the motor it ran at about 25% of its normal speed. Before I decided the motor was the problem, I pulled the motor and ran it on straight DC and it was whipped!
Pulled a extra Blue Box motor I had and tested it to see how many amp’s it took to stall. It stalled at .85 amps and free wheeling was pulling .35 amps. But, the motor was making a rasping sound when I ran it. Tried oil and it helped just a little. Installed it in the chassis and have ran it around 600 feet or so, sound is still there. Engine does run great and hauls caboose!
I know this is a age old question, any ideas on how to quite the motor down?
The sound could be caused by a dirty commutator. It could also be caused by the brushes pressing hard against the commutator. You try shortening the brush springs by cutting off one coil at a time until it quiets down. Make sure you have spare brush springs on hand before attempting that. I use it as a last resort.
Glad to see I’m not the only one frustrated with slow locos!!
If it has the replaceable brushes they can be a source of sound as well as bearings. Does it make a lot of noise running but with no driveline? You can take down the driveline and check. By disabling portions of the driveline, trucks, etc you can help pinpoint. Also a lot of times I make a cradle out of thick double sided tape(multiple layers sometimes) to help absorb the motor noise–this works better than the harder plastic motor mount.
There have been some articles over the years including MR magazine. I believe polishing the commutator has been one method. I’ve also seen folks recomment TV tuner cleaner to clean the commutator but I don’t know if that is sold anymore due to environmental restrictions on carbontetrachloride (memory is a bit rusty).
Of course the more universal solution is motor replacement.
Richard, it was making the sound before I installed it. So it is the motor, not the drive train.
Jeffery and Rodger. I have all ready cleaned the commuter with CRC. Jeffery, I have not cut the springs or polished the commuter yet. I know, I should have all ready but I want to see if it was any quieter with the shell on. Think we all know the answer to that! [(-D]
After I try the above ideas I might try switching out the ends of the motor with the one that I just took out. It was very quite, and very sloooow.
Yeah, the shell will just amplify the sound, turning a whisper into a rumble so to speak. I have a 70’s era Atlas GP40 that’s a prime example. The motor is original to the model and has a lot of miles and hours on it. As a result it’s a little noisy. With the shell off you can barely hear it. Put the shell on and it has a very definite rumble. And it is the motor, not the gears. As I said before I think your problem has to do with the commutator/brushes. It’s a rather common problem with these old blue box motors. Nearly all my blue box motors run very quiet. I have two that still rumble a bit but in their cases it rather adds to the appeal of the models.
Often there is quite a bit of slop (resulting in noise) that can be remedied by motor disassembly and adding washers (athearn and/or NWSL) on the ends of the motor shaft.
That was my solution to an Athearn loco that I affectionally called the ‘Athearn Grinder.’ No amount of tinkering ever got it to quiet down so it sits on a shelf waiting to be re-powered - some day.
I certainly have heard and seen some very nice and quiet Athearn engines over the years so it must be possible. Back in the 60s some guys polished the surface of the commutator using a typewriter eraser (a WHAT? lol) followed by a pencil eraser. And clean out the little gaps in the commutator with a pin. Others lightly applied a lubricant which they then mostly removed.
An article in the January 1966 Model Railroader by J W Mathews Jr “Adjusting Motor Brush Tension” might be the article referred to above. It is an open frame motor however.