Do I use center shank, overshank, or undershank Kadee coupers for an athearn Blue-box F7?
With my Blue Box Athearn F7s, I have gone to using the American Models Athearn close coupling modification. It is quite simple to work with and a Kadee #5 or a center set whisker coupler drops right into it at the correct height.
Don; Prez, CEO or whatever of the Wishram, Oregon and Western RR
Athearn HO Scale Coupler Conversions (kadee.com)
Straight from the source. Scroll down to your F7.
James in Texas
I grind down the frame to remove the built-in metal box on my Athearn BB models. Then I drill and tap a hole and install Kadee draft gear. I use a #5 for the rear and one of the long shank couplers for the front to get through the front pilot.
It takes an iron man to play with a toy iron horse.
There are lots of approaches to installing Kadee couplers on these locos, and if you are not concerned with improved appearence than the Kadee instructions are fine.
But the first suggestion is by far a much more realistic yet functional approach.
The American Limited close couping setup for the Athearn F unit is reliable down to 22" radius or below, looks good and is easy to install/work on.
We covered this recently on this forum, but here are some pictures again for the non believers.
And front couplers don't have to stick out unprototypically to work:
Coupled front and back on 22" radius curves:
Sheldon