Couplers keep coming undone

I use small dental rubber bands used for braces. Stretch them so they seat back behind the the 'thumbtack' and they're not very visible at all.

I found a bunch of small black rubber bands that I use for problem couplers, they blend right in.

GRJ, do you remember where you bought them? What actually causes the coupler to open up? Does the thumbtack piece snap down due to lack of tension?

@Trestleman1 posted:

GRJ, do you remember where you bought them? What actually causes the coupler to open up? Does the thumbtack piece snap down due to lack of tension?

Both Hobby Lobby and Michaels have them about $1 for a couple hundred.          j

Thanks for all the information!

You can also use dental rubber bands. You can find them on ebay>

                                                        Mini zip ties are a quick reliable fix.

                                                          Lionel scale items are the worst.

Kadee scale couplers don't have this issue, but it does require better than average track work for an even track height.  With lobster claws I often just zip tie the offending couplers.

Couplers not staying closed is a common problem on certain vintage of MTH equipment.

The wire tie, or a bit of floral wire is a good solution. Superglue will likely gum up the works and make sure that it can never be fixed properly.

I have used the rubber band trick, but found that it only lasts a few years and then the bands rot off.

Thanks again for all the information!

@Trestleman1 posted:

I bought a set of 6 MTH premier N&W 4-bay coal hoppers ( 20-97061) at a train show a few years ago. The couplers continue to come undone sporadically. Does MTH have a replacement coupler that is better or is it just easier to super glue the couplers and call it a day?

On my Lionel trucks PW and new I have used Hot Glue works great, and you can get it out if needed.

God Speed, Thank a Vet over Christmas

Converting to Kadee works well also

If the lackluster holding power of a coupler has a metal coil spring and you still want it to function correctly with Uncoupling track, here's a fairly easy fix that I did to a recently purchased used box car with this issue.

Remove the e-clip and washer and set aside.  Slightly stretch the spring to about 5/16-3/8" length and re-intstall.  Works like it's supposed to again.

After taking all the springs out I discovered 4 of them were about an 1/8" shorter than the other 8. Not sure how that happened. I'm going to stretch the 8 longer springs and the go to the local hardware store and see if they don't have a suitable replacement for the 4 short springs. If they don't then I'll try rubber bands or zip ties. Thanks again for the input! Don

If you're planning to replace the shorter ones anyway, there's probably no harm to be done by trying to stretch them first to see if that fixes the issue.

I feel like it's probably been recommended here a few times already but rubber bands are the standard "keep the darn thing closed" tool both myself and a few people in my club like to use, although I don't use the dental bands like others here recommend, I just get normal ones and wrap it around the coupler a few times till it's good and tight, it's beyond ugly but there's no way that a coupler with this done it will uncouple no matter what.