great idea. 
Not to go off the rails here, but what was the reason for the 'spring in the flywheel' trick? Not to be confused with the 'banana in the tailpipe" trick. Was the universal coming apart?
BTW- this is not my photo or loco- but I know exactly what this person is trying to do.
Correct. This is not part of Beardenizing because the inner bearing blocks are retained and there is a U-joint. As Dave said, when the Beardenizing procedure is done correctly, no spring is needed.
For this photo, this was another trick I and others developed- but it is a bit of a hassle.
I did this way back on the Atlas forum when I was researching why some Atlas SD50s and 60s would buck up and down like broncos (I think this only effected first generation releases- the answer I discovered was that the main drive gear at the top of the HT-C truck was coming loose. But this was actually a rare phenomenon).
In this exploration, I had an SD50 that was a bit rattly. I found that there was too much play in the worm between the bearings. It would wiggle back and forth laterally. The spring, inserted into the flywheel, places tension on the worm shaft pushing it away from the flywheel and reducing rattling.
The problem with this solution (which does work when done right) is:
1. It takes a LOT of experimentation to get the spring the perfect length.
2. If the spring is too long and too much pressure is applied, the friction goes up and performance goes down.
3. Big hassle if you ever need to take the loco apart again.
A little piece of tissue may work better.
