Remove the existing springs, then lift the garage door to its fully open position. Have a friend lift one side while you lift the other to open the door evenly. Hold up the door with one hand while attaching vise grips to the track directly under the bottom roller.
Connect an eye bolt to the back hanger of the horizontal track. Tighten the eye bolt with a wrench and make sure that the open end of the eye is pointed up.
Hook one end of the extension spring on the eye bolt.
Attach the front pulley to the other end of the extension spring. Insert the U-shaped clip through the end of the spring. Attach the pulley by inserting it between the U-clip ends and securing it with the provided nut and bolt.
Install the pulley on the front part of the horizontal track closest to the header of the door opening. Insert the bolt through the track flag from the inside of the track. Place the pulley on the bolt from the outside of the track and secure it with a nut.
Pull the door cable over the top of the pulley located on the track. Thread the end of the cable over the top of the spring pulley and pull it back through the bottom of the pulley.
Thread the cable through the front hole on the three-hole holding plate. Locate the three or four adjusting holes for the S-hook toward the front of the horizontal track.
Pull the cable until the spring is slightly stretched. With your free hand, align the other end of the three-hole plate with the closest adjusting hole and tie the cable to the plate. To tie the cable, loop it through the middle hole and underneath itself and pull tight.
Insert the S-hook in the open end of the holding plate, then insert the hook into one of the adjusting holes on the horizontal track.
Tie one end of the safety cable just above the eye bolt on the back hanger. Insert the other end through the spring, making sure that it comes out on the outside of the pulley.
Pull the safety cable tight and tie the end to the farthest adjusting hole on the horizontal track.
Repeat the steps for the opposite side of the garage door.
Hold the door with one hand and release the vise grips from the door track. Close the door about halfway and let go. The door should float up slightly to its open position. Adjust the springs if necessary.