A question about Proto 2000 GP7s. I bought 4 of these in 1999 and all ran smoothly and relatively quietly. I have not used them a lot, but have given them regular exercise. Three of them still run great. One has just suddenly developed problems: When entering a curve (even 30" - 32" radius) it starts to make a chattering noise. After running for even just a few minutes, the chattering is accompanied by a screeching noise, even on straight track.
I disassembled the unit. Lubrication is good and not excessive. There are no cracks or flash or grit in the gears or axles. Separated from the frame, the trucks/gear towers move very smoothly and quietly when pushed along the track. The motor turns quietly when disconnected from the trucks. But when all is put back together, the chattering and screeching resume.
I’m at a loss. Does anyone have any suggestions as to what is wrong and how it might be fixed?
Take a closer look at the axels. Unless you have replaced these gears with either Athearn or free replacements from Walthers, you may have split gear syndrome. The crack is hairline, but you can tell if you can easily turn the wheels of one axel in opposite direction. (you have to have the axel out of the truck).
If the gears are not split, the wear may be on a gear that is inside the truck; BUT maybe on the inside that rides on a mounted peg of the truck ect.
Run the loco without the shell on it and at least determine WHERE the sound is coming from. It may be only that something has come loose, which actually happened to me!
Even if you can’t see any cracks in the axel gears, they are still the most likely candidate these units didn’t really have any other issues. Your description of the problems definitely fits. Contact Walthers for the free replacement gears for all of your units, change them out and be done with it.
Jlarch, I thought all of my Proto 2000 GP7’s and GP9’s were cracked gear free as well but upon further investigation I found 9 out of 12 had the cracked gear problem. Pop out the wheels and give them a slight twist and I bet you will see they are cracked.
Remove the wheelsets from the loco. Take the wheels of a set between the thumb and index finger of each hand and see if you can turn them in the axle gear. You don’t have to put a lot of pressure on them, just enough to see if they’re loose. If you can one or both wheels in the axle gear the gear is cracked. Walthjer’s will send you new gears, no questions asked. In the interim, the gears from an Athearn Blue Box loco are a drop in replacement.
Thanks for the suggestions of changing the axle/wheelsets. I had some replacements on hand and tried them. Didn’t cure the problem. The GP7 still screeches. I might have to take it all apart again and give another look at other components that might be cracked (though I couldn’t see any cracks anywhere the first time around, even with a magnifying glass).
If you’ve eliminated the axle gears as the culprits, then it could be that the worm bearings and/or the motor bearings are in need of lubrication. Nine times out of ten, in my experience, that’ll be the cause of a loud screeching sound.
Have you checked to see if anything is causing the wires to contact the driveshafts or flywheels? I’ve gotten screeching and grinding noises from that sort of thing happening before (my IHC 2-8-2 is a good example; the wires were being pushed into the flywheel by the shell, so I built a hood around the top of the flywheel. Hasn’t made a sound since [:D]).