Discussion in 'FAQs' started by Freelancer, Nov 14, 2002.

  1. Freelancer

    Freelancer Member

    I have an Athern deisel that has a problem. When it takes right turns it is fine, but when it goes left it sounds like its gears are grinding or something, it is a very obnoxious noise. Someone once told me that it could be my radius. It is a large engine, and I am running it on an 18" radius, but I was wondering if maybe some oil or something might help. I have no idea what to do, any help would be great.

  2. jon-monon

    jon-monon Active Member

    I would try to isolate the noise. Maybe remove the body and press down on different areas and see if pressing somewhere makes it get quiet.
  3. 60103

    60103 Pooh Bah

    Another check would be to turn it upside down, apply power to one truck and turn the other back and forth to see where the noise starts. Then do it for the other truck. Youi may be able to see something when it's running. (and not have to take the body off yet)
  4. tomfassett

    tomfassett Member

    If it has "C" trucks, you are lucky it doesn't derail on the 18" curve. As for "B" trucks, my older Athearn GP35s all do this (the grinding noise). It is caused by the binding of the shaft as the truck turns too far out of line with the motor. I have noticed that the SWs don't have a problem on the 18" radius, but the new GP38-2 grinds a little bit like the older 35s. I just tore up an of 18" radius and replaced it with a 22". Now I have no problems in this area. I can even run some of the SDs over it, though some of the older ones (like the Athearn SD9s and SD45s) tend to want to jump the track. The other areas I can't tear up or I would have to replace the scenery. It is a problem that prototypical engines have that (for the most part) has been solved in the modern engines. Modern engines have axles which have a slight side to side movement to allow them to curve with the track instead of putting lateral pressure on the rails while trying to keep all the axles perfectly in line. I have a very old Atlas SD35 that can negotiate some fairly small curves due to the fact that it has been run so much that it has worn bushings where the wheelsets seat in the truck frame. You can actually see the wheels shift back and forth slightly as it rounds a sharp curve. It still grinds a little as the shaft binds slightly as the truck rotates out of line with the motor.
    As an experiment (about 15 years ago), I cut the center out of the drive shafts on a GP35 and replaced them with a broken section of spring like material which came out of the shaft of a flex shaft tool (like the dentist used to use). The good news is the grinding went away immediately. The bad news is it took me 5 hours to retrofit the thing properly. I decided long ago to just live with the grinding noise rather than do the other 40 or 50 models...:D :p

    Tom F
  5. Vic

    Vic Active Member

    Sounds like the problem is in the universal joints and/or the alignment of the motor.

    You'll note that the motor sits in a rubber/plastic mount. Be sure that this rubber mount is seated all the way down into the frame of the loco. If its up on one corner or side the universal joints will be misaligned. Be sure the little rubber pegs are firmly seated in the holes in the frame. They sometimes come loose in shipping. Just push straight down on the motor to re-seat it and give it a gentle twist to align it straight.

    The next thing to look for is flash in the plastic universal joints. Disasemble them and using a magnifying glass look for plastic flash in the couplings. If found just gently scrape it away with an Xacto knife. A little plastic compatible grease on the joints won't hurt either.

    An Athearn loco is going to have some degree of noise but it should not make the grinding noise and the above will usually cure it. Also check to see if the metal contact strip is hitting a universal or drive shaft when the trucks turn. If so, just bend it a bit to get it out of the way.

    Hope this helps:)
  6. Railery

    Railery Member

    Its good to know what kind of engine u are running. But for a rule of thumb, u are best to stick with B trucks for 18"r . C trucks will drag (bind) or grind in a tight curve and depending on how many cars u are pulling. OR u may have to get out the exacto blade and check for any plastic spurs(flashing) or edges that may be catching on the trucks or even the gears. i know from dragging, my first layout was 18", than 20" and finally i expanded to 22"r. Still had problems but my new layout i decided minimum radius to be 24" on inner curves and my max is now 30" on my outer. Its only a foot more for my dog bone.

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