Freight car help needed

I have several freight cars with trucks that I am unable to tighten and, as a result, they wobble down the track. It appears that the threads have been
stripped, and the screws no longer hold. Does anyone have suggestions for solving this problem?
Jeff
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Jeff Stanton wrote:

I assume the cars are plastic. In this case, you can remove the trucks and the screws or pins that secure them. Use plastic rod (sprue often works) to fill in completely the truck screw holes. Glue the rod with that clear watery plastic cement. Let dry thoroughly (overnight). Cut the rod off flush with the truck bolsters and then file or sand a flat smooth surface for the truck to mount on. Get some pan head machine screws 3/8 " long and either 6-32, or 4-40 if the 6-32 screws won't go thru the hole in the trucks. Mark the center of the new truck hole with a sharp punch, making enough of a dimple to guide the drill. Use a pin vice and a #43 drill for 4-40 or a # 36 drill for 6-32. Drill clean thru until the drill breaks thru inside the car. Give the truck bolsters one more swipe with the file to clear off any drill shavings. Then drive in the machine screws, letting them cut their own threads into the plastic hole. Old timers go for a "three point suspension, one truck as tight as possible (short of sticking) and the other truck a bit looser, allowing a little side play to let the wheels follow minor imperfections in the track.
David Starr
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David Starr wrote:

OP doesn't say, but if he's referring to HO cars, he'll need 2-56 screws.
[...]
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Wolf Kirchmeir wrote:

Of course it depends upon the car. I use 6-32 screws to hold the trucks on my IHC streamline passenger cars. I like the biggest screw that fits into the truck on the theory that big screws hold better in plastic than small ones.
David Starr
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Thanks for the reply. You have all been a great help. Jeff

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Jeff Stanton wrote:

If you tighten one truck screw down just enough to swivel, yet prevent wobbling, and leave the other one free enough to wobble, the car will negotiate your track with stability.
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You don't really want to over tighten the trucks -- a certain amount of play is needed. The trucks need to both swivel (for curves) and tilt (grade changes, super-elevation). And *some* wobble is prototypical.
That having been said, you might want to drill out the holes and use machine screws with nuts. Probably #2-56 would be the size you need to use. This assumes that the freight car bodies can be removed from their floors. This might be 'awkward' for open cars (gondolas and hoppers), unless you have a 'load' you can snap in (to cover the otherwise exposed nuts).

--
Robert Heller -- 978-544-6933
Deepwoods Software -- Linux Installation and Administration
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Robert Heller spake thus:

Actually, David Starr's techique given above is superior. Using nuts on machine screws is an invitation either to binding by being overly tight, or to not fixing the wobbling.
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wrote:

Depends on the bolster hole -- Athearn's (old) 72' passenger cars use #2-56 screws and nuts -- this was to conduct current for car lighting. The bolster hole has a flange agrangement, so when the screw is 'tight' (not over tightened!), there is just the proper amount of play to alow the trucks to move as needed. The downside to David Starr's techique is that the plastic is a *relatively* soft material, so the threads tend to strip easier. There is a bit of trade off here. And as been noted, the trucks need to be a *little* loose to allow for both swiveling for curves AND tilting to allow for track imperfections and grade transititions -- in other words *some* *slight* wobbling is not only normal, it is needed for proper operation. *Excessive* wobbling is of course bad.

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Robert Heller -- 978-544-6933
Deepwoods Software -- Linux Installation and Administration
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Once your cars are on the track, the screws shouldn't affect their stability. The weight of the car on the trucks should be all that is required for stability. There should be a central boss on each bolster over which the center hole of each truck fits. These center the trucks and in the case of truck mounted couplers the boss transfers the tractive effort/pulling force.
One of the two bolsters should have two pegs on which the relevant truck sits (well when it's upside down on the bench, when it's in operation they should be the other way up ;-) That stops the car from wobbling sideways. The other truck rides on the bolster at the center around the boss. The two different mountings form a stable three point mounting for the car body, like a three legged stool.
If your problem is just that the threads of the mounting screws have stripped, then either fit a larger (PK) screw, or drill out the boss and glue in a length of Plastruct or similar plastic tubing. That's a task which requires a lot of care to achieve. Another option would be to buy junk cars of the same brand/type (Ebay) and replace the damaged portions from donors. (the beginnings of a large but always useful junkbox :-)
Regards, Greg.P.
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