garage door lift cable loosens as door reaches fully open height

[Jeff Heuer]

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? Thanks, Jeff

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[mkirsch1]

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.

The cables are not winding on the spools evenly. They should wrap a single layer of cable on each spool. If you look, you will probably notice that one spool has the cable wrapping on itself. This causes the effective diameter of that spool to be larger, and to wind up cable faster.

[jeff_wisnia]

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:

Jeff

[Bryce]

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.

[jeff_wisnia]

Or maybe somebody replaced one of the cables with one which wasn't quite the same diameter as the other.

The thinner cable would get slack even if it wound in a single layer on the pully.

Jeff

[Twayne]

Omigosh, I'll have to keep track of that! Good catch! What's the most accurate way to measure pi anyway? My protractors always give me somewhere between 2.5 and 4.5 on my half-inch diameter circles! The stupid center keeps moving around!

< G >! :^}[

[The Daring Dufas]

Now, now, it&#39;s not polite to make fun of people. We&#39;re not all rocket surgeons here.

TDD

[merey.anne1]

I need a hand with something. I have installed a new door, got everything set up as it should be, but for some damn reason when the door raises about halfway the cables want to come off the rollers. The cable winds perfectl y on the roller until it just doesn't stay on, as if the cable is too stiff or somthing. This is stupid.

[mike]

Count the cable turns on each pulley.

If the springs are matched to the weight of the door, you need to tighten the cables to the point that they are still in tension in the up position. If the springs are not matched to the weight of the door, you're gonna have to live with a compromise.