When we built the Bockscar we picked 37 degrees, basically what the rails were running. It went straight, quite a bit of pressure was required to steer at speed. Was that way for about 26 years... we broke an axle last year, decided to build a new one for this year. The new axle has about 14. Steering is definitely different... there is a lot less pressure required to steer. The flopper is gone, it backs down the trailer easier, and pushes by hand a little straighter... at 37, once the front started to flop, it went. I made a couple of passes before Pork Pie took the reins, I like it at 14 but I may add a reversed quickener to allow a little more wheel movement. It seemed to steer too easy.
Pork Pie had no trouble keeping it on the track, even with the cross wind that popped up during his last record run.
Pick a number... 0 to 37... all have been used, these days I would say 37 is too much... 10 -15 is where I would land. Just remember caster is not your only variable, pay close attention to scrub radius and bump steer
