I have this little problem. I have a P2K GP30 that’s about 4 or 5 years old. It has very low miles on it, hardly any. I put in a SoundTraxx LC decoder and the sound is fine but of course the sound cuts out (known problem) and the motor buzzes (another known problem). So I added a Digitrax DZ123 to run the motor (and the lights too since the SoundTraxx decoder winks the LED rear light, another known problem). Now now the motor is quiet and the sound doesn’t cut out at all. But the loco doesn’t run smoothly. It looks like the wheels might be binding because it kind of lurches. Not terrible but so much that it ruins the entire experience for me. I have replaced the axle gears due to the splitting problem that is common to this model (still another known problem). Looks like the period of the lurch is about 2 or 3 inches of track.
What else should I be looking for? The wheels are in gauge per the NMRA tool. The wheels have no flat spots or other irregularities. The axles are not bent. The axle gears are pretty much in the center. Is there anything else that is critical to smooth operation down in the axle area? Is this perhaps a function of the relative newness of this loco? IOW does it have to be run in for a few hours?
Check the condition of the lubrication inside the trucks. Proto 2000 tended to overlube the GP30s (among other models) with a lube that doesn’t react well to time and idleness. The GP30 used a “clone” of an Athearn truck, so checking the lube should be pretty simple - just pop off the bottom gearbox covers and see what you have in there. If you find “glue”, you’ll need to tear the trucks down, degrease them and relubricate with new grease or oil.
Thanks for the lube idea. I checked that out and it looks fine. However I did find that one of the axles was not properly seated as one of the square bearing blocks was out of place. So I fixed that and it ran much better but still far from perfect.
On further inspection I found an incredible thing. One of the axles is different from the others. It is a slightly different color and the tread diameter measures .475 instead of the .455 of the other 3 axles. I imagine that would have some effect on performance.
I’ll be calling NWSL tomorrow to get some decent wheels for all four axles.
Check the wheelsets for cracked gears. This is an old story with P2K GP30’s. See if you can (gently) turn the axles within the gears. If you can or they just don’t feel right the odds on favorite is that the axle gear is cracked. Athearn axle gears (I use gears from old Blue Box F7’s) are an almost perfect drop-in replacement. Also, Walther’s in many cases will replace the wheelsets free.
I own a small fleet of PK2 GP30s. Some of thme started running rough. I checked and several of them had cracked gears. I emailed Walthers about the problem and they mailed me replacement wheel sets (free) for all of my PK2 GP 30. Changing the wheele sets was very simple.
I would bet the railroad you have one or more of the bad P2k axles. Call Walthers and they will GLADLY send you replacements free. I did about 8 or 9 Geeps with anywhere from 1 to all 4 axles needing replacement. There are previous forums on this problem (one I generated) and if you go to them you will see how easy of a fix this really is.
Walthers was especially good about this, so don’t hesitate to call them.
I have a P2K GP9 that had the same problem, and was in the same state.
Turns out I needed to break it in.
Just run yours around for a few minutes in each direction, changing the speed every now and then, occasionally going to WOT. (It leveled stopped lurching after about 10 minutes)