Athearn cars never came with dumby couplers. They used Accumate couplers up untill a year or two ago. You can convert these to McHenrys just by opening the coupler box and replacing the Accumates with McHenry couplers. They use the same truck.
Me thinks you are talking about Bachmann, train cars as they are the only ones I'm aware of that used screws to hold the truck in place. Athearn is a relative new comer to N scale. If so, then Unimate makes a dummy coupler that works very well as a substitute. Easy to install and drop in place just like a Rapido Coupler.
Either just couplers or trucks - I may be wrong about their being Athearn as there is no markings anywhere as to brand. I'd like to put magnetic couplers in place of the dummies - I tried McHenry's but they don't fit in the small coupler box.
I know all Athearns I have touched to date have screws that hold the trucks on, and I have some of the newest rolling stock from them being the Auto-max's... As for conversion I just cut the molded in bolster pin, file the area down flat, then use a drill bit in a hand drill open up the screw whole to the proper size for the Micro-train pin to snuggly slide in to hold the MTL truck/coupler on. I've done this to a lot of Athearns.
No no. Too complex. For MT conversion, just unscrew the original truck and discard it. Replace with MT truck. Place MT washer over truck bolster hole thingy. Re-install original screw so that it holds down new MT truck with washer. I. E. Screw holds down washer, that holds the truck in place. True, theres a bit of side to side slop. But it its not very noticeable to me in the grand scheme of things.
If you want unreliable rolling stock this is perfect. I tested this method and caused too much play, specially with long trains and tended to have problems. As soon as I used the proper bolster pin any of the problems I was having went away. It's not that complex in the scheme of things compared to some of the stuff we do in this hobby.
My apologies, I just looked at my Athearn hoppers and they have a phillips head, ugly little screw holding the trucks in place. Typical of Athearn. I think what threw me, is the time line or aging analysis. What I consider to be old and you newbies and youngsters consider to be old, are two different things. Yep, I barely remember thinking that way myself...at one time. Now when was that? Grin! Unfortunately, now I have the same question. So, if you don't mind an old fart riding along on this thread... we can look for the answer together. Now does anyone have a foot puller. Must remove foot from mouth. Grin! Edited add on: I do agree with Mavrick. Allow me to add my two cents. The washer thing causes the car to ride to high...top heavy. The car rides to sloppy and the freight trucks has way to much freedom of movement. Restrict that freedom of movement and you will have a good riding car. Dejavu, sounds like the Athearn F7, discussion between YoHo and I yesterday. Same principal applies in both applications. A simple case of the wobblies.
Thanks - you're right - I tried the washer idea first and rejected it because it rode far too high. Cutting the molded bolster pin, sanding it, and opening the hole for the MT pin was really easy and worked like a charm. Thanks again!
