jeff_wisnia wrote:

wrote:
On Jul 22, 11:51 am, (Jeff
Heuer) wrote:

One of my garage door tension springs broke and I replaced both springs
with a set that had previously been used in a friend's garage for only 5
years. We installed, them, wound them so that the door was balanced, but
then when raising the door by hand to check it's operation manually, one
of the lift cables loosens as the door reaches the full open height.
However the other lift cable remains tight and working properly? We've
tried adjusting the tension in the spring on that side of the door to no
avail? Can you tell me what might be causing this lift cable to loosen
as
the door reaches full open height so we can fix it? I will call a
professional at last resort, but we've handled everything other than this
lift cable staying tight issue so far and would like to finish the job?


There are two types of door spring systems. It would help if you
mentioned which type you have.

I have to assume that you have the type with the two springs on a bar
directly above the door opening.


You may well be correct about that, even though the OP did say "tension
springs", not "torsion springs".....

But he also said "wound them"...

If they are tension springs then one of them may have "softened" or
stretched more than the other. Or, the friend's garage door may have had
a different weight than his and used different strength springs.

The first time I replaced the pair of tension springs on one of my
garage doors I used a bathroom scale with a simple wooden lever to
measure the weight of the door sans spring assist to determine what
strength springs to buy. (Some springs are color coded re strength but
my old ones weren't.)

I won't bet either way, though if they are in fact torsion springs the
OP might want to spend a evening or two reading Richard Kinch's epic
monolog about the subject:

http://www.truetex.com/garage.htm

Jeff

All of the torsion spring doors I have worked on used a solid shaft that
mount the springs and take-up pulleys. The pulleys turn in unison and
throwing slack at one end means unequal effective diameters ... unless
the OP has encountered a local variation in the value of pi.