Lionel GP9B SuperBass Coupler Clearance Issue

Just a follow up in case anybody else runs into this issue and finds this post.  I contacted Lionel customer service about the issue and they sent a replacement coupler.  (Very quick turnaround, about a week from email to part received).  Unfortunately the coupler was the same as the one that came with the unit and suffered the same uncoupling issue on curves.  The new coupler worked the same way, the 'Thumbtack' slides under the pilot on curves causing the coupler to open.  It appears that it may just be a design issue that the loco cannot navigate curves that are more narrow?

While I was disappointed at first that I essentially still could not use this brand new dummy unit, it occurred to me now that I had an extra coupler.  I figured I had nothing to lose by trying to just remove the 'Thumbtack' portion of the new coupler.  I drilled out the top of the 'Thumbtack' (Mentioned here in a few other freight car coupler posts) and the 'Thumbtack' came right off.  I installed the new coupler and now the loco works on curves as it should.  Still unfortunate that a brand new engine doesn't run correctly out of the box, but if you can get a replacement (or just want to modify the one that came with it), the solution is pretty simple.

That’s one way to go.   If you want the functionality of the coupler then either Lionel needs to provide a coupler with the thumbtack further back or we need to take a dremmel to back side of pilot and remove the interference.  

Hey- another KNOWN thing on these- they using the shortest screws they think they can get away with leaving minimal thread engagement for holding the electocoupler. The screw is an M2.5, with integrated washer but barely long enough to only thread in maybe 4-5 threads into the truck mount post.

If you do not resolve this- you are likely to see your coupler droop and then fall off.

I used both loctite and a longer M2.5 screw to prevent a future failure- and just repaired for a customer- the same exact thing on both ends of a normal Legacy 2024 model GP-9 for the same reasons.

At a bare minimum- check yours and use loctite now before it falls out and you lose the screw and centering spring- let alone having the coupler hanging by the wires.

Also, you can remove the pilot (2 screws from the bottom) and turn the truck far enough left or right to reach the elecrocoupler mounting screw and see the centering spring. Like I said- minimally make sure to add threadlock and the screw is tight, but a longer screw and threadlock is even better insurance.

Parts listing from the last run of GP9s (since all the 24 year ones blank) https://www.lionelsupport.com/...GACY-GP9-484-6-84280

Note- I used a longer M2.5mm X 6mm long for better thread engagement- the mounting point is fully tapped.

I wonder if the coupler could have been secured with a cable tie to keep it closed to solve the problem?

@vettekid68 posted:

.After looking at the bottom, it appears the issue is the 'thumbtack' on the coupler is bumping into/under the pilot on curve sections causing it to uncouple.

-Tom

Thanks for posting, Tom, I came here researching the exact same issue. I have the new AEC B-unit and it has the same issue. Easily reproducible, happens consistently, I'm surprised that none of the reviews out there mentioned it!

I figured the answer was going to be to replace the coupler with one that doesn't operate, rather than the thumbtack one. I might contact Lionel like you did just to get an extra one to work with.