If you can… Often the door in the up position blocks access to the springs, leaving you no choice but to do it door down. Part of the reason it’s so dangerous. Wouldn’t have to manually build so much tension if you could leave the door up to install them.
Those are the torsion ones. The tension spring kind will just whip you with a steel cable that’s going fast enough to amputate fingers.
Always put the spring in its least tensioned position (door up) before fucking with it.
If you can… Often the door in the up position blocks access to the springs, leaving you no choice but to do it door down. Part of the reason it’s so dangerous. Wouldn’t have to manually build so much tension if you could leave the door up to install them.