I just noticed that our garage door hangers were not installed correctly (previous owner). The problem is that the end of the tracks is about 5" short of the next joist, so the hangers were improvised and there are no sway bars. They really barely resist lateral movement and one of the tracks is really crooked.

Does this mean that the tracks are of the wrong length? I never installed one myself.







I'm thinking of running two punched angle irons in parallel between two joists. One above the track and one to the side. Then support hang the track from one of the punched holes above it, and run a diagonal sway bar to the other angle iron.
The blue lines are the joist locations. The red lines are the parallel angle irons, and the green is the right angle triangle with the sway bar.



This is a bit complicated, any other ideas? Should I replace the tracks with ones of the right length?

 

Your thinking is correct as the rail needs to be stabilized in a similar fashion as you show. Make the cross piece go across the joist to where it can be lagged to the joist in two places, then angle two more pieces of angle iron, not flat strapping, to the ceiling mounted angle, bringing them together at the rail. One more observation, is that plant hanger performing any structural duties? It is cast metal and has no strength, so it really has no place in this setting for holding things together.

Attachment 81250

While that utilizes the one joist available behind the track, using two pieces of angle laterally about 6" away from the track fastened to two joists and connecting your v angles to it may be better.

 

Thanks. It was hard to find punched angles above 14ga, but I got a few Colpay punched angles from HD of the right thickness.

 

Roger that. Very good. Bet it feels more stable, now.