I've provided this information for free, in hopes it will help you either fix your door yourself, or find a competent professional service to do it for you at a reasonable price. If you've been helped by this Web page, as many have, all I would ask is that you create a link to this page (http://www.truetex.com/garage.htm) from any pages you maintain. You will thereby help others searching for complete and reliable information on this type of repair to find it with a Web search.
Note that I am measuring a spring that is fully relaxed because it is broken!. The length of the relaxed, unbroken spring is the specification of interest. It is harder to measure unbroken springs on an intact door because the springs should not fully unwind, even at the top-of-travel. If you can't be certain of the spring diameter from indications on the cones, then you have to go through an unwinding procedure to relax them fully for measurement, or perhaps reckon the size from measuring the somewhat smaller diameter at the nearly unwound condition when the door is at its top-of-travel (although one should not attempt to raise a door with a broken spring).
The open-ended work-order trick: You may be very surprised if you allow work to proceed without signing a work order with a specified price. Or, you may sign a work order, and think you're protected against open-ended wallet-reaching, only to find a much higher price due at the finish than you expected, because you signed a "parts as needed" order that got loaded up with a long list of parts (that likely were still in serviceable condition). You might have been quoted a price, but then get a bill for that price plus a lot more added for the "service call" and the "parts", and be told the quote was just for the labor. While this is the normal way of abusing your finances down at the hospital, you shouldn't agree to it for a garage door service call. These guys are not doctors.
Great! We specialize in all sorts of garage door repair work. Working around the garage door can be fairly dangerous if you’re trying to repair this issue on your own. Most garage door companies will quickly remind folks about this, and it’s true. Their are some hazards to watch out for when working around these heavy and high tension doors. We recommend you give an expert a call to address the issue in a safe and timely manner for you.
Now 13 pounds of force must be respected when backed by many hundreds of foot-pounds of stored energy, waiting to be released. Holding this torque is equivalent to stalling a 3 horsepower DC motor. But holding and turning these handles does not require extraordinary human strength. Note that this maximum tangential force depends only on the weight of the door, and the radius of the drums, and is divided by the number of springs (some designs have only one longer spring, as mine did originally, instead of two shorter ones). Higher or lower lift distances imply more or less turns to wind the spring (and thus a different spring geometry), but not more force on each turn.
Horsepower is another key factor when it comes to garage door openers. Look into ½ horsepower garage openers if you have standard aluminum doors. Oversized doors and one-piece doors may require 3/4, 1 or 1¼ horsepower garage door openers. Garage openers with higher horsepower use less effort to operate and minimize wear and tear on the motor. This is ideal if your garage doors act as the main entrance to your home.
Roberto was very courteous and explained the details of what he was doing. He also pointed out a repair I might consider having done (replacement of the bottom panel of my door) and asked the office to follow up with me on this. Someone did follow up with me and since replacement of the bottom panel is not an option and I would have to replace the door, I decided that I can wait.
Two of the spring references specifically for the garage-door industry are the APCO Spring Manual by Bill Eichenberger, and the Torsion Spring Rate Book by Clarence Veigel; these give tables of spring sizes and torque constants. Spring engineering principles in general are described in the Handbook of Spring Design published by the Spring Manufacturer's Institute; the formulas allow you to calculate torque constants knowing only the geometry and the Young's modulus of the material. You can also find some brief spring information in standard references like Machinery's Handbook and Marks' Standard Handbook for Mechanical Engineers.
Remember, not all garage door springs are alike. They are not one size fits all. If yours breaks, make a note of the brand and color code on the spring you need to replace. We'll get you the garage door opener parts you need, from seal kits to torsion and extension spring kits. Save money by replacing garage door hardware instead of replacing the whole unit.