Over the years Lionel has made some really nice passenger cars. I am a big fan of their 18" streamliners and heavyweights as well but they all suffer from a way too large coupling gap. To quote another formite, they couple in the next zip code.
When Lionel came out with their UP Excursion Cars they made gap especially wide. I discovered two reasons for this. The first they actually made the modern style "tube" diaphragms too small in addition to having the couplers stick way more that necessary. Little excuse for this as the cars use the newer kinematic couplers and automatically extend further in the curves.
I sought to address both issues. Another forum member posted a pic of the actual UP tube diaphragms. What I discovered is the tubes don't mount directly to the rear bulkhead but rather to a short I beam. My replacements include this beam and are also slightly larger in diameter. 3/16" OD vs 1/8" OD for the Lionel ones. To assemble these new diaphragms I made a couple of simple jigs to glue the styrene together, pictured below.
The second part of the modification involved repositioning the couplers. I have used Kadees in the past but wanted to retain the big knuckles to easier mate with my other equipment. That and kadees don't work the best on the club modular layout which can have some uneven track sections.
To do that it was a matter of tapping new holes in the frame for the kinematic couplers to mount to. I also replaced the springs with shorter ones found in eBay.
So here are the results.
First as they come from the factory. Olympic broad jumpers would have a hard time passing between cars.
With new diaphrams, stock coupler position.
New diaphragms and couplers moved inward 1/4".
Excursion Car Coupled to a Challenger car with traditional diaphragms. Challenger car coupler moved inward 1/4" as well.
Picture of the prototype showing the two different diaphragm types together.