Torsion Springs Weaker Than Measurements Indicate

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Old 12-05-11, 12:19 AM
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Torsion Springs Weaker Than Measurements Indicate

I have a Clopay 7 x 16 garage door, Model 73W3, with W4 Windcode struts installed. There are a total of 6 horizontal struts installed. The track radius is 12. The cable drum diameter is 4. There are two regular torsion springs. The original springs are still intact, but have been in place for 11 years and I want to replace them before they break.

Clopay customer service says the door as configured weighs 259 pounds. The door has been painted, so that could add a pound and make it 260 pounds. There is nothing extra mounted on the door to add weight.

The original springs measure 1.75 x 32 x .243. I measured wire size using 20 coils and verified the wire size with a micrometer, so I am sure it is correct. The springs are currently wound 7.5 turns.

HOWEVER, two 1.75 x 32 x .243 torsion springs wound 7.5 turns should lift around 295 pounds, but the door is still heavy. It falls closed from halfway and still weighs 35 pounds when fully closed. This has pretty much been the case since the door was installed.

Is it possible that the door actually weighs 295 + 35, or 330 pounds? I tried weighing with an analog bathroom scale by turning the spring shaft until both cables became relaxed and the scale read 260 pounds. This is very close to the 259 pounds stated by Clopay.

Why do the original springs not fully support the door despite their measurements? Is it possible that the original installer used springs that have that much less lift power than their measurements would indicate? Are there such springs? How do I verify what size springs to buy?
 
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Old 12-05-11, 10:22 AM
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You might be overthinking this a bit. Visit Clopay and download their standard torsion spring adjustment instructions. They provide a winding table for your door height. My guess is that the torsion springs installed may have come with the doors and are probably dimensionally standard.

My Clopay doors have the EZ set torsion springs. They are very easy, and safe, to adjust. If you have standard torsion springs you need to be aware that they can be dangerous to adjust if you don't know what you are doing.
 
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Old 12-05-11, 10:49 AM
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I may have over-explained the problem.

Let's assume the door weight is correct at 260 pounds as verified by the bathroom scale, then forget about the door and just look at the springs. A torsion spring design table for 4" cable drums will say that a 1.75" ID spring that is 32" long and has .243" wire will pull 148 pounds each (a total of 296 for both) when wound 7.5 turns. These are pulling about 112.5 pounds each (a total of 225 for both). Why?
 
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Old 12-05-11, 02:02 PM
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The springs are weak due to age.
 
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Old 12-05-11, 02:22 PM
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I think someone has been reading at this site....Garage Door Torsion Spring Replacement

Everything you ever need to know about garage door springs...
 
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Old 12-05-11, 04:08 PM
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Originally Posted by figpickle View Post
The springs are weak due to age.
I agree with figpickle, the springs weaken over time and they are probably ready to break, If you can give me a drum number I can check spring size with an app on my ipod
 
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Old 12-05-11, 04:33 PM
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The cable drums are 4" in diameter.
 
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Old 12-05-11, 04:55 PM
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Originally Posted by vivona View Post
The cable drums are 4" in diameter.
Sorry need an actual drum number, should be DNS 4x-8 left and right?
 
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Old 12-05-11, 05:07 PM
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Are you sure the springs aren't 2 in ID? because with 1 3/4 by .243 at 260 lbs the springs should be 35 long
2 inch by .243 at 260 lbs they should be 31.5 inches long
there might be a tag on the left or right flag bracket that tells you spring size
 
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Old 12-05-11, 05:29 PM
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The drum has OMI-8-LH stamped on it. Is that what you need?

I will verify spring diameter and get back with you.
 
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Old 12-05-11, 05:40 PM
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Originally Posted by vivona View Post
The drum has OMI-8-LH stamped on it. Is that what you need?

I will verify spring diameter and get back with you.
Also, are you measuring the springs wound? they grow 2 to 3 inches as you wind them and get slightly smaller in diameter. Getting it off the tag is your best bet or give up and call a pro would be my suggestion, torsion springs are very dangerous and not worth the trip to the hospital
 
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Old 12-05-11, 09:05 PM
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I sincerely appreciate the warning about working with torsion springs, but I am very experienced in working with risky mechanical projects and feel confident that I will follow the proper procedures and take the appropriate precautions.

The winding cones have 1 cast into them and the wound springs measure 2.125 in OD, which is slightly less than the 2.236 OD of 1.75 springs. So, I am sure they are 1.75 ID springs.

Is it possible that the springs simply were made from wire that has a lower spring rate than wire normally used for torsion springs? Or, could the original installer have tried to increase profits by installing weak used springs salvaged from a heavier door?
 
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Old 12-06-11, 11:59 AM
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I think you are now asking questions that no one can possibly answer.
 
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Old 12-06-11, 03:23 PM
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Actually, I just found the answer to my own question. They do make torsion springs from different tension wire. Here is a spring with dimensions of 1.75" x .243 x 31.5 with a pull of 130 pounds.

Garage door springs

And here is a spring with the same dimensions with a pull of 140.6 pounds.

Garage Door Torsion Springs

This being the case, it is not a given to just measure the springs and buy the same size. It appears that measuring the unsprung door weight is the best way to ensure buying the correct springs.
 
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Old 12-06-11, 03:57 PM
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Here is a place you can go to for a little more info. Includes info on the color coding.

Official Color Codes for Torsion and Extension Springs
 
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Old 12-06-11, 09:29 PM
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In my online research the two best sites on garage door springs were:

Garage Door Springs

And:

Garage Door Torsion Spring Replacement

Hopefully these can be useful to others that are looking for garage door spring information.
 
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Old 12-20-11, 08:09 AM
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As a followup, I ordered the long-life springs for a 260 pound door and have changed them out. The original springs were quite fatigued and stopped unwinding at 25 turns. That explains the heavy door.

Unwinding the old springs and winding the new springs was fairly easy as it only required a maximum of about 21 ft lbs of torque. Where people get into trouble is not using the correct winding bars or not paying attention to the winding procedure. The hardest part was stretching the new springs after winding. It was hard to keep the spring from sliding back before I could get the set screws tightened, but after a few attempts I got it just right.

My appreciation goes to the very useful instructions posted here.
 
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