I've been working on a legran limo, and I have found that, upon cloning the B pillar (between the doors, one for the front, and one for the back) that the JBeam vibrates a lot and causes instability in the vehicle almost instantly. I've tried lowering the beamspring values a lot, but it didn't seem to do anything. the nodes for the unstable pillars are between line 494 and 505.
Yeah, more node weight or less spring, try to keep damping at minimum possible. With damping too much and too little can cause issues. More beams connected to node requires usually higher node weight for same spring and damping. It is then adjusting up and down of values, trying to find out best balance. So it is like juggling.
I ended up bumping up the nodeweight of my added section, and that worked to make it stable, thanks for the advice!