[iamrfixit]

Sounds like you have the wrong springs.

Garage door springs are carefully balanced to door height as well as door weight. What height is the door you are working on? The rack of springs available at your local home center are by no means universal, those are simply the most common springs that fit the most common doors. Usually a very limited number that they choose to keep in stock. If your door is over-sized you may very well have to order the correct springs to fit your door.

 

[iamrfixit]

Hopefully you weighed your door with both springs disconnected? You need to weigh the door by itself, without spring assistance to get an accurate weight. Once you have that I would buy the new springs going by door weight and spring length rather than what the color code might be.

I'm not sure how closely the various door manufacturers adhere to one color labeling system. Unless you get the same brand of springs as the original as well as the same color code, they may not be the same spring.

 

[iamrfixit]

The springs apply different spring rate as they are stretched. If you stretch both springs the same distance the shorter would likely have more pull strength than the longer spring.

Spring power varies over the length of the stretch, and the amount of power required to open your door also changes as sections of the door transition to the horizontal track. That is why the correct springs are so important, the margin for error is pretty small if you want the door to work well.

Your 8' tall door requires longer springs than a standard 7' door. If your door originally had 32" springs, then replace them with 32" springs.