I have several pieces of rolling stock that have trucks that cannot be tightened properly. The coupler height is good so I don’t want to install a washer between the truck and the bolster. All these trucks set on a round “boss” into which the mounting screw is threaded. I have cut this screws length thinking it was bottoming out before the truck is tightened but that was not the problem.
I see only two solutions myself and wonder if there are others.
File the top of the boss till the truck is stable but free to turn or
Take a look at the relationship between the end of the boss and the hole in the truck bolster. From what you describe, it is likely that the end of the boss is sticking above the surface where the screw head will seat. So the screw head tightens onto the end of the boss, but the truck still flops around. You can tighten the screw until you strip out the hole threads and never get the thing to stop flopping.
Gentle file the end of the boss until you get its end just about flush with the bolster surface and you should be okay.
Might try a little glue down the hole, let it set up and try again. Did I miss who made the car? I have all so used different screws, Walther’s sell’s brass wood screw that is just a little over 2/56 and I have used them to hold coupler boxes on. Sorry I don’t have the part number handy. They have threads all the way to the head.
Another thought: Perhaps the hole for the screw is stripped or cracked. If that is the case, I use a short length of 1/8" plastic rod. It has a hole in the center. I make sure the exposed end is square and smooth. I drill an 1/8" diameter hole in the bolster and glue in the rod. When it is dry, I tap the hole for the screw and screw in the truck.
Another, another thought. Try putting a dab of paint or a thread locking compound into the hole to see if the screw can be made tight. I prefer that to using glue in the hole. Paint is cheap and easily found.
You should be able to tighten the truck mounting screws to the point that the truck won’t swivel at all. Not that you want to run that way, but if you cannot tighten up that much, you may not be able to get the truck tight enough to avoid wobble.
I would drill the screw hole clean thru the bottom of the car. If the screw is bottoming out on the internal weight, I might drill out the weight to permit pasage of the screw. You can try larger screws. I have gone as big as a pan head 6-32 machine screw to mount trucks on IHC passenger cars.
Then you want to check the wheels. Bits of stuck on crud on the treads will make any car do the rhumba. Wheels can be cock eyed on the axles.
The screw is tight in the hole and the thread is not stripped. Maxman has the best solution, I just hate to file a new car. But I will. One end only Rioplumas.
It must be a very common problem. The evening news yesterday did a short–too short–piece on the local club’s open house. (Darn, missed it again!) They had a closeup video of a freight train in operation and the first thing my wife said was, “Are those cars supposed to wobble like that?”
You shouldn’t have any fear of doing this. If the mounting lug on the bolster is thicker than the flanged lip of the truck, no matter how hard you try to tighten the screw will the truck not wobble. Overtightening will usually strip the screw. Just use care and go slow w/ that file. The only reason I will use a washer is to raise a car easilly for proper coupler height. This is common w/ many BB kits.
There is one thing that I forgot to mention. When you file the end of that tube, you want to have the final surface parallel to what the existing surface was. If you file at an angle, you will end up with a truck that doesn’t wobble, but with a car that is tilted to one side or the other.
OK, here is what worked on one of my cars. I removed one truck and checked all the dimensions with NMRA gauge. (I did need to adjust one wheel.) Then I filed the top of the boss being careful to keep it relatively flat and level.Still too loose so I repeated the process until the one truck would rotate freely but not wobble. I see no need to do both trucks as the car doesn’t wobble now and, as said before, could cause a problem on uneven track. Not that I have any such track[:D]
Glad it worked out for you Bruce. When I posted the glue tip I did not know you could get the screw tight and truck still wobbled. Glue trick did work on some stripped out screw holes on 30 year old Athearn’s BB cars.