Union Pacific 4-8-4 problem

[Hoople]

My friend recently bought the Union Pacific 4-8-4 from the Overland Limited I believe, basically the NYC niagra in UP paint, and the instant he brought it over, we found a major issue. It wouldn't run around the curves without jerking. On my 22" radius curves, it would jerk, jerk, and wobble until the front driver would come loose, it would double in speed, then hit a turnout causing a short becuase the lead driver was off and hit the opposite polarity rail. Seeing as this is a trainset locomotive, I'm astonished it performs this badly. I checked for side play in the drivewheels, and there was harldy any.

Is this a typical problem? How can it be fixed?

Thanks in advance.

Mark

[SteamGene]

Any idea as to the age? 
Gene

[lanny]

Hoople,

If everything else is working okay, wheels are clean and it is properly lubed, you may need to go to a wider radius than 22" in order for it to run well. I have 32-36" + radius and one BLI 4-8-4 would not track well even on that radius.

Just a 'guess' on my part. Best wishes on getting it to run okay on your layout.

lanny

[Hoople]

Any idea as to the age? 
Gene

I don't know. I didn't get the chance to go inside of it.

Lanny, this is a trainset engine, far from those BLI 4-8-4s which also should work on 22" radius also. I compared it to my bachmann GS-4, and the GS-4 had 5-6 times more side play than the Niagra/FEF, yet it's basically the same drivers.