I have an Athearn SD 40-2 that was wrapped in bubble wrap for 4 years before seeing the light of day last month. I cleaned it, applied light lube and when it moves forward everything is fine. When it goes in reverse, it makes a grinding sound at low speeds whether the body shell is on it or not. Nothing seems to be binding and I am at a loss. Anybody got an idea??
Check the washers on the worm gears, you may need to add one or two.
It seems that too much forward / reverse play in the worm gear causes a lot of the “Athearn Grind” issues.
Mark Gosdin
Ah, yes, that is the Athearn signature sound. Goes way back to the early days of the Blue Box models. You pay extra for that sound.
No more then a Atlas GP7 that had a grinding sound coming from the rear truck…A easy fix…One end of the gear box cover wasn’t completely seated.
Although most likely a truck/ worm problem, don’t overlook the motor/ brushes. This seems esspecially true on BB locos that have been stored for a period.
Early in the hobby, I strived to quiet these noisey beasts. I went through the usual, NWS wheel replacements, deburring any flash int he trucks, shimming the excessive play in the worm and motor/ brush tuning. For the most part, I was successful. I di note that units receiving continued use performed far better than stored ones. It seemed that a new breakin period was always needed. This usually was no more than just running it up in both directions for a few minutes.
Repowering to a decent can motor after some attention to the driveline produced the best performance in the BB line. Proto Power West chassis are an example of this.
Your reverse noise may just be brush noise. You can clean the commutator, even polish it. I have used a piece of worn 600 wet or dry over a piece of styrene to turn the contact portion down, removing dirt, scoring etc. Sometimes the brushes need reseating. Unless you are confident and experienced w/ motor tuning, don’t clip the brush springs to alter brush contact. I ruined many springs in this trial and error approach. Too loose a brush will cause it to dance and arc.
I think I can solve your problem real quick. Take your shell off and run it with out it. If the sound go’s away its the motor mount. You will have to replace it. Its the same problem I had with one of mine SD-40-2 and a SD-40-2t SP’s and they were the old BB Athearns loco’s. Also watch the motor if it rocks back and forth this means that the motor mount has broke.
I recently purchased an Athearn SP F7A that was discounted on closed-out and presumably in storage for a long time. I don’t mean to resurrect a long-dormant thread, but after disassembly of this otherwise nice engine, I have concluded that the grinding sound is caused by the forward dog-bone joint not being fully seated in its receiver. I’m not sure how I’m going to reset the tension on this joint since it’s embedded in the forward fly-wheel but I’m going to try. It only took a few hours’ running before this problem started. In this case I don’t think that this problem is necessarily caused by dried-out lubricants which was my initial thought.