I know this was done to death years ago, but I wasn’t paying attention because I hardly had any Bachmann. I have more now, and room to run long NG trains. But I can’t because the Bachmann cars and coaches like to uncouple randomly, even on very smooth track and very wide curves.
I recall that years ago, several folks described a solution. Besides changing to another coupler type. 
Can anyone post their solution or point me to a resource that describes such a solution?
Thanks,
Paul
There are essentially two issues with the Bachamm Big Hauler couplers. First is the mounting. Out of the box, the couplers are mounted to a tang/tongue (depending on your favorite term) on the truck. This causes the coupler to ‘droop’ and not be stable. This is not terrible if you are only pulling the cars in operation. If you are doing switching operations, they get much more likely to cause a derailment if you are pushing more than one or two cars. Switching to some form of body mounting will aid this issue greatly. There are several threads on body mounting the standard Big Hauler couplers.
Second issue is in the coupler itself. MY SOLUTION was to carefully disassemble the coupler. There is a small spring that opens the knuckle, make sure to contain it when you push the pin out of the knuckle. Carefully, using a sharp (said new) Xacto #11 blade, clean all the flash off all the mating surfaces of the three operating components (knuckle, body, and drop pin). Pay close attention to the drop pin. Sometimes the plastic does not form quite perfect and you will get a high spot. Again, carefully with a fine file or emery board flatten the high spot. I DO NOT RECOMMEND any form of lubricant, wet or dry. Carefully reassemble the coupler and it should perform considerably better. Be prepared to spend some time if you plan to do it right. Doing them in mass will speed up the process, but I found keeping the parts to each coupler together seemed to be more reliable. Doesn’t make sense, but that was my experience.
All of that said, I have been on a slow process of converting to Kadee ‘G’ coupler, which play quite nicely with the Big Hauler couplers. One transition car allows me to mix and match body mount Kadee, body mount Big Hauler and truck mounted Big Hauler couplers.
Good luck.
Paul;
I don’t wish to add to Bob’s very good suggestions. I am just hoping to provide some insight as to why Bachmann and other brands of couplers seem to uncouple at random. I got into large scale in the mid-1980s. At that time, the only uncoupler offered was the LGB uncoupler. The device mounted low between the rails to raise the hooks on the LGB hook & loop couplers (you needed 2 of them if you had added hooks to all your couplers). Other brands of large scale trains tended to mount their couplers low so they could be uncoupled with the LGB uncoupler. Unfortunately, twigs, pebbles, acorns, small pine cones, & etc. also worked very well to pop the couplers open. I finally converted to Kadees to end the random uncoupling frustration. If you run outdoors, the “track inspector” needs to check the line prior to operations. The “track inspector” can be your eyes, or a device like “Groucho” below.
Best wishes, David Meashey
This is about couplers but not about Bachmann. Will USA have parts at the National show. I just discovered that I cannot connect my Aristo-Craft E-8’s to my USA passenger cars. I have cut up all my USA couplers to convert them to A/C couplers. What I need is a wide vision caboose coupler because it is so long and can be cut and drilled to the correct length to match the A/C coupler length. So the question is can I find a USA coupler to solve my problem at the show. I would like a chance to run my passenger train if given the opportunity.
Thanks
Paul - Yes it was maybe 20 years ago TOC (Dave Goodson) discussed a method to replace the plastic pin that that the copler head pivots on with a small machine screw and nut. That alone significantly corrects the droop problem. A few years later I did a photo essay over at MLS on how to do it. That essay is long gone but I still have the pictures on-line. Here are a few, you can see them all by going to https://photo.cvsry.com and opening the image files that start with BC.
I did this to all my Bachmann stock and it helped tremendously.
EDIT to add: It wasn’t on MLS - It was on my long forgotten website! The entire article is still intact at https://cvsry.com Click on Car & Loco Mods, then on Bachman Coupler Mod.
Jon, you are talking about replacing the head? I pulled the coupler out of the E-8 and the thickness if the drawbar is about the same.
The width is a little different.
Many thanks to Bob, David, Ron and Jon. I remember seeing Jon’s explanation way back when, and a few others, but I didn’t pay attention at the time, since I wasn’t running much Bachmann. I’ll keep these links and notes this time, I promise.
Ron Hill said:
Jon, you are talking about replacing the head? I pulled the coupler out of the E-8 and the thickness if the drawbar is about the same.
No, only the plastic snap in pin that hold the head to the shank.
Thans for the information. I pulled the coupler and I think the improvised coupler will work. I will work on it this weekend.
Hey Jon, the conversion worked well. Thanks for help. Just a little modifications and it fit. Thanks.
Jon thanks for the tip, I would recommend adding a drop of red Loc-tite to the nut threads. That will prevent the nut from unwinding and falling off from vibration.
Vic Smith said:
Jon thanks for the tip, I would recommend adding a drop of red Loc-tite to the nut threads. That will prevent the nut from unwinding and falling off from vibration.
I used Blue, but yes. Something needs to hold the nut fast. You can’t tighten it or the head will not pivot.
On the page it says…
Add a drop of Threadlocker on top to help hold the Nut in place and replace the coupler assembly on the truck.