There are many types and brands of residential and commercial garage doors on the market using a variety of styles of counterbalance systems. All the different spring systems are designed to assist with balancing the doors weight allowing the average person to easily lift even the heaviest of door manually. In the event you have a garage door opener it takes some of the burden off the motor and drive system. Electric openers are only designed to guide the door up and down not to actually lift the door's weight.
Torsion springs are by far and away the most popular style and are used by about 90% of all manufacturers in one form or another. They are mounted on a 1" shaft directly above the door in a single or double configuration. On most doors the spring will be centered in the middle of the door but on rare occasions they are mounted directly to the cable drums or located near the back of the door tracks for cases where there is a low clearance situation. This system provides a very calculate lift amount measured by inch pounds per turn (IPPT) based on the weight of the door, it's height, the track configuration, cable drum size and cycle life.
Cycle life is the number of times you can open and close your door before you would expect your spring to break. Torsion springs can be bought with a variety of different exterior coatings from your standard oil tempered, galvanized, stainless steel or the most popular which is a rust inhibiting black coating. Torsion springs can be very dangerous and should be handled with extreme care. If you are looking to repair or replace your torsion spring yourself they can be tricky to locate and typically will require you to purchase them online.
You can expect to pay between $20-$50 per spring based on its lifting capacity and cycle life. Most online places that you can buy springs from also provide a good online source that will guide you through the process on how to simply measure your garage door spring. Don't forget to order your spring winding bars when you order your springs. There is no substitute for having the right tools.
The next most popular spring system is probably the garage door extension spring. The stretch spring lifting system has been around for a very long time. These springs are generally located just above the horizontal door tracks. The spring gets its lifting capacity from being pulled or stretched as the garage door closes. Most garage doors use a single spring system utilizing one spring on each side of the garage door track. The springs will have a cable pulley secured at one end of the spring and the other end will be anchored where the door tracks are supported. A cable will run from the garage doors bottom bracket up to a cable located just above the door around the pulley that is secured to the spring and back to the front track area. Garage door stretch springs are rated by there lifting capacity usually using a weight. If you need to purchase springs for a door weighing 160 lbs you would order 160lb springs. The pair together would be capable of lifting the 160lb door.
If you are unsure of the doors weight simply get the assistant of a strong neighbor lift the door slightly and slide a bathroom scale under it. Typically this style spring or spring components can be replaced relatively easily with the door secured in the open position. You can buy extension springs online and also on occasion find a small selection at a hardware store. You will pay somewhere between $15-$29 per spring for most extension springs depending on its lift capacity.
Lastly we cannot leave you without mentioning the newest latest and greatest system to hit the market. The Wayne Dalton Torque master Spring is extremely safe and easy to install and garage door repair Tujunga CA, with basic hand tools. The spring is actually located inside the tube and tension added to the spring with a standard power drill or wrench. The torque master spring system uses all the same calculations and engineering that goes into a torsion spring but is neatly slide inside a teardrop shaped tube out of the elements.
Generally these springs last approximately 10,000 cycles or so and provide a very smooth quite operation. Unfortunately Wayne Dalton is the only garage door that comes with this system. If you are looking for a DIY door to install it's the door I would recommend for the safety reasons alone. If you are looking to buy a replacement Torque master garage door spring they are a little hard to come by and can only be bought through a Wayne Dalton garage door dealer or a online retailer. You can expect to pay between $50-$75 for one spring or $90-$120 for a pair of springs.