Measurements: With the door in the down position, I measure a wire size of 0.273 inches, outside diameter of 2.0 inches, and overall length of 41.5 inches. Relaxing the spring shortens the length by about 7.5 coils of wire, so to estimate the relaxed length, we deduct the wire diamter of 0.273 inches times 7.5 from the 41.5 inch wound length, yielding an estimated relaxed length of 39.5 inches. The mean coil diameter is 2.0 - 0.273, or 1.73 inches. Perhaps this was actually a 40-inch-long spring with a 1.5 ID, 1.75 mean diameter, and 2.0 OD, but let's continue on calculating with the actually observed sizes. The number of coils in the relaxed spring is the relaxed length of 39.5 inches divided by the wire size of 0.273 inches, or about 145 coils. Deducting about 5 dead coils at the ends yields 140 active coils.
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See the Sectional Overhead Garage Door catalog (PDF file) from the Prime-Line replacement hardware company. Their brochure Sectional Garage Door Torsion Spring Installation Instructions (PDF file, part number GD-12280) is brief but informative. Apparently you can only obtain their torsion springs as special order items through mom-and-pop type hardware stores like Ace and True Value, and not the big-box Home Depot and Lowes.
The history of the garage door could date back to 450 BC when chariots were stored in gatehouses, but in the U.S. it arose around the start of the 20th century. As early as 1902, American manufacturers—including Cornell Iron Works—published catalogs featuring a "float over door." Evidence of an upward-lifting garage door can be found in a catalog in 1906.[4]
Loosening or tightening the set-screws is the moment of most risk, since the end-wrench is a potential missile if you slip, and your hand is close to the cone. When the wrench is removed and only the rods are in place, it would seem that the worst that could happen is that the rod is flung out and the captive spring and cone rattle around, assuming you are keeping yourself clear of the rod's radial disk of rotation, and not leaning on the rod such as to fall into the apparatus were the rod to slip out of your grasp. The torsion shaft design has the virtue of capturing the mass of the spring and cones reliably on the shaft, preventing these parts from launching themselves as projectiles, even in an accident.
By watching the chalk mark while winding, you can count the number of turns applied, and confirm the number later. My standard-size door (7 foot height) with 4-inch drums has a nominal wind of 7-1/4 or 7-1/2 turns, which leaves 1/4 or 1/2 turn at the top-of-travel to keep the lift cables under tension. After 7 turns on the first spring, I clamped down the set-screws, weighed the door again, and found a lift of about 100 pounds in reduced weight. As expected, this wasn't quite half of the full 238 pounds, nor would it leave any torsion at the top-of-travel, so I added an 8th turn. The door now weighed 122 pounds on one spring, which was ideal. After winding the other spring, the door lifted easily, with only a few pounds apparent weight. This confirmed that the spring choice was properly matched to the door design. I engaged the electric opener trolley, and adjusted the opener forces down to a safer level suitable for the new, improved balance. The door was now ready for return to service.
As noted above, set-screw clamping may have distorted the cross-section of the shaft and made it difficult to slide off all the hardware. With the shaft on the floor, it may be possible to restore enough roundness to proceed, using compensating clamping force to the distorted area via a machinist's vise, an arbor press, a hydraulic shop press, etc., on the shaft body. Burrs and other slight distortions on the shaft can be filed off with a hand file or touched with an abrasive wheel on an angle grinder. At some point, the condition of the shaft may just be degraded enough that it ought to be replaced.
Once the springs are relaxed and loose on the torsion shaft, the lift drums lose their tension on the lift cable, and the cable comes loose. The end of the cable is terminated by a press sleeve, which locks into a ramp on the drum. Different drum styles have a bolt or other method to fix the cable end to the drum. These steel cables are springy and won't stay in place without tension. If my pre-inspection had showed that these cables were worn or frayed, then I would have ordered proper replacements ahead of time from the spring distributor, since this is the opportunity to replace them. Standard hardware-store cable and fittings are not appropriate.
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Additionally, the B970 includes encryption features that prevent others from hacking the system to gain entry to your garage. Expert reviewers like this garage door opener a lot. The Tool Spy says the Chamberlain B970 justifies its higher price point by delivering excellent build quality and anti-vibration features. Consumer Search and Garage How To also approve of this unit.

Leveling the door: Before commencing the spring winding, to check that you have the door properly leveled on the cables, considering all the factors above that make this a tricky adjustment, apply the winding cone setscrew lightly to lock the (unwound) spring cone temporarily on the torsion shaft, and momentarily lift the door slightly off the floor. Adjust the drum set as needed to level the door, repeating this slight lift test. Loosen the cone setscrew before winding the spring(s).

When you install a new garage door, replace all the hardware as well. If your automatic opener doesn’t have an automatic reversing system that includes photoelectric eyes, replace it. Doors with openers also require two extra pieces of hardware that you’ll see in Photo 4: a support strut (usually included in the door kit) and an opener bracket (not included). For doors with torsion springs located over the door, spend the $50 or so to have a garage door professional release the tension.

Beware of improprer prior installations: Sometimes the existing door installation is not correct, and the old springs should not be used as a specification for replacements. For example, the old springs might have been replaced with incorrect sizes because the last repairman didn't have the right one on his truck. If your door has never worked quite right, something like this might be the cause. To correct this, you must use the weight of the door to specify the spring, either from a spring rate manual giving spring torque constants, or from the formulas below.
The "liability" angle: The flip side of "safety issue" is "liability". This is not used to directly sell you something; it is used to demean the cheaper alternative and prod you into buying a more expensive (and profitable) option. For example, you may be pressured into buying a whole new door, when you just need a new spring, by the salesman telling you he can't just replace the spring due to "liability" issues. Since product liability is a big burden on the garage door industry, and so many old doors (and especially automatic openers) are dangerous, this may be a genuine reason to accept a higher price.

Wood - Wood garage doors are sturdy and quite beautiful. However, if you live in a humid climate, your doors will be prone to rotting and splitting. If your wood is painted, you must also factor in the costs of painting as part of your regular maintenance routine. The cost of repairing the wood varies depending on the type. However, average cost to repair a wood panel is $190 to $215.

However, if you are confident that you don’t just need new batteries, make sure to call a professional. A service person with a lot of experience will be able to look at the problem and quickly diagnose the issue, saving you precious time. Again, while you may be able to save money in the short term by taking a day off and troubleshooting the problem yourself, the amount of energy and time lost as you search out the issue will quickly surpass the cost of a professional repair.

Having a mismatched pair makes it difficult to specify the correct matched-pair replacements. To obtain replacement springs for a mismatched pair, you can either specify the same odd pair, try to calculate the equivalent matched pair sizes, or (this is the best method:) measure an accurate door weight and calculate the right spring size(s) "from scratch". The spring seller should be able to do the calculations from your accurate measurements of weight, height, and drum size; or you can attempt the calculations yourself using my engineering formulas below.
Checking if the lift drums need resetting: The old position of the lift drums on the shaft may have slipped or otherwise lost the the proper position, requiring a reset of the drum position on the torsion shaft. You will also reset the drums if you are replacing the lift cables, since the new cables will not exactly match the length of the old ones. Problems like uneven tension on the cables, or a tilted door, or a door that doesn't easily stay aligned with the tracks, can be due to an improper "set" of the drums on the shaft. So one shouldn't assume the old positions are correct. Setting the drums on a "fresh" part of the shaft will avoid the possibility of damaging the shaft from retightening in the same dimples.

Smartphone Control: Many newer garage door openers allow you to connect the device to your home's Wi-Fi network, according to RW Garage Doors. You then can open and close the door through a smartphone app. In fact, many of these apps will give you an alert on the smartphone when the garage door is open for a certain period. Some opener models even can connect to your existing Smart Home system, incorporating all your appliances on one system.
In the photo, you can see an extra lag screw on the bottom of the plate, reinforcing weak anchoring from the original two screws (hidden behind the springs). This extra screw was applied by a professional garage door technician on a previous repair visit. I have since replaced the backing with a sound plywood panel anchored into the concrete door header. Since these bolts clamp all the opposing torsion to the wall, the attachment must be sturdy.
Our garage door installation and repair professionals are courteous, knowledgeable, skilled and dedicated to your satisfaction. Let us show you what we’ve done for so many businesses and homes throughout Cincinnati and northern Kentucky when it comes to their garage doors, and what we can do for you. Once you’ve tried our services, you won’t have to search for a garage door service provider in this area ever again.

I obtained my parts, as described on this page, from American Garage Door Supply Inc. ( They may have raised their small-order prices or imposed a minimum order since I ordered from them in 2002 at the prices in my essay above. The Web site offers a free catalog by PDF download or mail. Springs in 2005 were priced at $2.25/lb.

Location, climate and building codes are just a few factors to consider when determining which type of garage door is right for your home. Depending on the region you live in, you may need to choose a wind load option for your garage door. Wind loaded garage doors help safeguard your home in high wind prone areas. With garage doors serving as the largest and often times the primary entrance to the home, an insulated garage door may also be right for you.