When I installed my (used) wooden garage door some years ago, the door
was made for an 8 foot high wall, thus the door is about 7 feet. My
garage walls are 9 feet tall. But I needed to save some money and had
that door, and really did not need the extra height. The only problem
is that the rails were 2 feet lower than the ceiling rafters. I just
installed a couple 2 foot 2x4's. Shortly after, one of them split
from the spring pressure, so I added another 2x4 (doubled it). That
worked fine but I soon had to add some angle braces because the 2x4's
were pulling loose from the rafters (by the nails). A year later one
of them almost pulled off the rafter, so I added carriage bolts.
After that I was fine until a couple months ago when one of the spring
cables broke. The spring launched, completely destroying the entire
(double) 2x4 and brace, and the spring ripped apart some shelves in
the rear of the garage in the process.

I am finally getting around to fixing this. I got new cables and also
got a set of safety cables so if it breaks again, no one gets hurt.
However, I am wondering if I should use some of that angle steel
rather than 2x4's this time. It's made for that purpose. But it's
not the thickest steel, and while it might work for a one foot or less
drop, will it support a 2 foot drop without buckling? On the other
hand, I could use some thick angle iron for the main support and just
use that thinner garage door steel for the braces.

I know I can make something work, but was wondering if anyone else had
used that angle stock made for garage doors and if it was strong
enough for my needs.

Thanks