Garage Door Cable Length?

[like2wheel]

How much should the cable wrap around a high lift drum when the door is down?

Long story short, I ordered a door & tracks for a 8' door in a 12' wall & was shipped a 8' door, tracks & a 4' high lift extension.
That all needed more than 13' of wall, so while modifying the tracks, I decided to make them also follow my 4/12 roof pitch.

So now I have exactly what I want except; cables that are too long, wrong spring, & possibly wrong drums. It works "ok", but I have to use a prop to keep the door open all the way.

The cable is too long to ever get to the large part of the drum, so I'd like to shorten it to see how much better I can make it. I do realize that I'll eventually have to figure out what would be the correct spring.

 

[LB-1911]

This might be where to start -

The necessary length of cable varies based on the door and the style of lift: vertical-lift and high-lift doors require longer cables than standard-lift doors because of the positioning and style of the cable drums. For standard-lift residential garage doors, the cable length should be the door height plus 18 inches. When measuring an old cable, measure the full length including loops, spools, thimbles, and stops.


http://ddmgaragedoors.com/parts/cable.html

Do-It-Yourself Garage Door Instruction Library

 

[pattenp]

I have a high lifted 8' door on 12' wall lifted 3'. With the door down there is about 3/4 of a starting wrap on the large end of the drum.

 

[like2wheel]

Thanks, that's very helpful!