Extension spring selection for short door

[Stuff]

One of my winter projects will be installing new springs for the garage door of a 70 year old house. I don't know if the door is original but it is a four sectional wood in good shape so will be keeping it for now. The door weighs 125 lbs. but is only 6' 3" high with limited headroom so don't want any torsion solution.

Since most springs are sold for 7' doors any spring won't extend as much so would not hit it's rated strength.

7'=84" and 6' 3"=75"
125 lbs. * 84/75 = 140 lbs.

Does anyone have experience to say this is right or wrong to use a set of 140 lb. springs?

 

[jstroede]

If the door weighs 125 lbs use 130 lbs even with the reduced height.

Sent from my XT1254 using Tapatalk

 

[Stuff]

Thanks. I see several places stating Works on garage doors that are between 6'-6" and 7'-5" high but not saying what do do with shorter doors.

I guess extension springs aren't as precise and this 6'3" door is a rare bird.