I recently bought a Lionel PW 2338 GP7 and had to replace the power truck since the one I bought was seized. I also added the spring washer between the truck and frame since I saw it was missing. It runs and coasts fairly good on my 027 track. I have little experience with GP7 but just doesn't seem to pull that good without cranking up the voltgage. Then I noticed this extra shaking and what I think is excess noise.
The loco shimmies laterally within the track, more so over the power truck. The first thing you notice is the Milwaukee logo shakes and the cab rocks back and forth laterally, especially on curves. When stationary, it doesn't seems to have any more lateral sloppiness in the wheels that other locos.
So Im looking for any suggestions to diagnose the problem and fix.
I did my typical clean and lube of the gears, axles, etc and cleaned the motor and lubed. I didnt spot anything abnormal in doing this.
Thanks,
Bob
So I solved the issue.
In the greenberg repair manual it looked like the spring washer was to be installed between the power truck and the frame. I was bothered by this because I thought I remembered other locos had this sppring washer between the verticle motor and the frame. I switched it out and the problem is gone.
Well I ran the GP7 today and the shimmy is back. Now Im stumped, Geartrain?
looks like 4-5 Hz shake to me.
Anyone have any ideas or similar issue?
Im thinking it may be a wheel lateral runout issue on the power (motor) truck.
One wheel seems worse that the other three. But not severe.
Does anyone know what the lateral runout of the wheel should be?
And what should be the lateral wheel to wheel spacing? Has to be bigger that the track spacing but I dont know the tolerances for these dimensions.
Thanks
I have had older Lionel diesels shake and shimmy from wheels that were not quite drilled centered when produced, axles that are a little bent or tweaked due to one reason or another. Back in those days, if it ran well kids and so forth were happy. We have gotten spoiled by newer models that run smooth and are free of shaking and so forth. I would try running the model upside down on the work bench with test leads and see if you see a wheel with a bit of a wobble on the power truck as that is where I seem to always find them. Rarely on the non powered truck. Mike
Silly NT's, I have Asperger's Syndrome
Thanks Mike for you suggestion.
I did that and discovered that both wheels on the gear side have more runout, one more radial and the other lateral than the two non-geared wheels. It looks to me to be excessive. I have anothe GP7 that is from 1971 or so and it has some radial runout but no significant lateral runout. It uses similar truck and motor and does not have a shimmy issue.
Appears that the used power truck I bought has wheels that are causing the shimmy issues and higher voltage requirement when they are on the track.
Have you considered returning to the original truck? Often a siezed mechanism just needs to be given a very, very thorough clean. Old lubricant is fantastic at jamming up old gears, hit it with something to soften the grease, and then scrape out as much as you can access.Also, if it is a magnetraction equipped truck, checking for something that got jammed in the mechanism is always a good idea.-Ellie
"Unless bought from a known and trusted dealer who can vouch otherwise, assume every train for sale requires servicing before use"
[quote user="Leverettrailfan"]
Hi Ellie,
Yes I have. I did my thorough clean and lube without success so I bought the replacement. But yesterday I went back to the original to see if I could fix it. The gears can move just a little because of gear backlash so they look free but I cannot move the wheels at all. I put oil in the bushing days ago and cannot budge them with neednose pliers. So last night I soaked them with WD40 which I normally dont use. One axle is now free, the other is still seized. So Im going to try some more wd40 on it.
Sounds like a good plan- was there anything to suggest rust or corrosion? That would explain why a clean and lube wouldn't budge it, but the WD40 was able to.I also might throw out the idea of tapping the ends of the remaining seized axle with a hammer- there should be a slight ammount of side-to-side play, so perhaps giving a gentle tap could help break up whatever's seized the axle, combined with the efforts of the WD40.Good luck, I hope things go well.PS: Another thought- perhaps you could get a better grip and more leverage using a set of large vicegrips. Just wrap the jaws up in several layers of electrical tape to avoid harming the wheel. Needle nose pliers strike me as not being the easiest tool to spin wheels with, and you might need that extra leverage just to break the initial friction.-Ellie
You might try a small drop of Marvel Mystery Oil on the rotating parts of the frozen truck. I've never used it on toy trains, but I have had some success using it on other things.
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Still have problems
in Conclusion,
I got everything freed up and running. Lots of wd40, lots of sore thumbs and fingers, a little hammering. Picking with a sharp thin knife around the bearings and spraying flushed out iron paticles. Flushed out the wd40 with contact cleaner. Dried with an air compressor, then lubed it up.
Shimmy is gone, or at least not noticeable. Coasts longer, and goes faster.
A success.
In the end, the other power truck had too much runout.
Thanks for everyone's suggestions.
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