The Chain Drive Rail Extension Kit for 10'-High The Chain Drive Rail Extension Kit for 10'-High Garage Doors is required for reliable everyday operation of Chamberlain chain drive models in 10-ft. garage door applications. Featuring a quick-install extension rail and replacement chain the kit includes everything needed for quick and easy installation. Includes one-year warranty rail extension replacement ...  More + Product Details Close
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.
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.
Install the stiffening strut on top of the top section of steel doors with the section lying flat. Then install the opener bracket that replaces the center bracket between the top two sections. While you’re working on the sections, protect them from scratches by putting carpet scraps on top of your sawhorses. Now, slide the rollers into the roller brackets.

Install the vertical roller tracks first by wrapping the curved lip around the rollers. The top of these tracks should be approximately 8 in. below the top of the top section. Wait to install the upper tracks until this step is complete. Check the level of the top section to make sure the tops of the vertical roller tracks are level with each other. The bottom of the roller tracks should be at least 1/8 in. off the concrete floor. After leveling and mounting these tracks, install the upper roller (horizontal) tracks.
The optician's trick: The serviceman looks over your door with lots of scowling, chin-scratching, and tsk-tsking. You ask, "how much?" He replies with the fair price. If you don't flinch at that price, he says, "for the parts", while quoting a large additional cost for the labor. If you still don't flinch, he adds, "each," while pointing back and forth to your pair of springs. (I hope none of you service people are reading this!) I call this the "optician's trick" after the old vaudeville joke about lenses, frames, and left/right.
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.

I repeat my caution about the uncertainty of interpreting color codes. A professional installer reading this page emailed me to say that the red color indicates the springs are right-hand windings, not the DASMA color code for the wire size. But this photo shows both a right- and a left-hand spring, and both have the red paint on the cones and set-screws. I conclude it is prudent to make your own measurements and analysis. Do not rely on the colors on old installations. The only time I would respect them would be on new parts that carried documentation giving the code.
Your garage door is used often, generally more than any other door on your home. Therefore, it’s important to make sure that it’s tough, dependable and weather resistant. Our doors are fully capable of meeting all these requirements and are specifically designed with our customers in mind. While durability is important, so is appearance and we offer many different styles and colors of garage doors to match your home or business.
An extension spring counterbalance system consists of a pair of stretched springs running parallel to the horizontal tracks. The springs lift the door through a system of pulleys and counterbalance cables running from the bottom corner brackets through the pulleys. When the door is raised, the springs contract, thus lifting the door as the tension is released. Typically these springs are made of 11 gauge galvanized steel, and the lengths of these springs are based on the height of the garage door in question. Their lifting weight capacity can best be identified by the color that is painted on the ends of the springs.

The various increments of standard wire sizes differ by only about 0.010 inch, so calipers or a micrometer would be the tool to use to be certain of the stepped size you have, or else a trustworthy ruler marked in tenths of an inch to use the measure-10-turns-and-divide-by-10 trick. The most common wire sizes in the US are 0.207", 0.218", 0.225", 0.234", 0.243", 0.250", and 0.262".
In each of our branches, we have the best team of expert professionals who know how to handle each and every type of garage door and its components. This is because all of our technicians go through a rigorous training process, covering every known garage door repair technique. We do not let them onto the field until we know that they are completely trained, and can perform a job to perfection. Aside from this, they are continually updated with all the latest knowledge, information and training in order to do their work efficiently.

You might genuinely need some extra parts when you thought you simply needed a broken spring replaced, and a good serviceman will perform a simple inspection to identify such parts. Nor is it unreasonable for a business to charge separately for a service call versus repair work actually performed. But the best protection for you as a buyer, being somewhat at the mercy of whomever you decide to bring on site, is to understand what is being done, and ask intelligently for a clear explanation or demonstration of why extra parts are required.

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