I spent the afternoon trying to figure out what is going on with this engine. I started by getting out another NP unit and placing it on my piece of straight track. Sure enough, no wobble and all 6 axles turn freely.
So back to my problem child. To keep track of things, I numbered the axle positions 1-6, front to back. This means slots 2 and 5 have the blind wheel sets. First thing I found out is I have 2 problems in addition to the wobble: Axles 1 and 6 do not spin freely. Front truck first: Once I pulled the pickups and bottom plate off, axle 1 spun freely. I pulled all 3 wheel sets free of the casting. The blind set practically fell out, but the other 2 took more effort, especially axle 1. I tried the blind wheel set in all 3 positions. It dropped in easily in all of them. Next I tried axle 3 in all 3 positions. Again, it went in and seated fully, albeit with a bit more fuss. Axle 1 is a different story. It was a real pain to get into any slot, and the geared side would not seat all the way down. I left it in position 3, as it seemed to fit the best in that slot. When I put the plate and pickups back on, I could not tighten the screw next to position 3 fully without binding the wheel set. I repeated the procedure with the rear truck, and found axle 6 behaved similarly to axle 1.
So at this point, I believe the truck castings are OK and I have 2 bad wheel sets. It is not the wheels or the axles, but rather the bushing castings. I’ll order a pair of wheel sets from MTH and see if they cure the problem.
Sidebar: I don’t think this a related to my problem, but I’m curious. Above axles 3 and 4 are a pair of metal pins with flat faces. There are holes above axles 2 and 5, but no pins. And above axles 1 and 6, holes don’t even exist. What is the purpose of the pins?
Chris
LVHR
