| It's 6:00 AM and you are leaving for work. You press | | | | door opener. Be sure to put your hand under the |
| the garage door opener wall button and hear a subtle | | | | motor before removing the last screw to prevent |
| hum from your electric motor but the door failed to | | | | the motor from falling. Slide the motor assembly off |
| move. If your garage doors springs are intact | | | | the drive shaft and place in a safe place. (Not on top |
| chances are you garage door openers main drive | | | | of the ladder for obvious reasons). |
| gear has failed. You can easily inspect your drive | | | | Step #11 |
| gears by unplugging your garage door opener and | | | | Remove the three hex head screws holding the |
| removing the metal cover. The main drive gear is | | | | sprocket assembly to the main chassis using a 5/16" |
| made of a white plastic that typically is the weak link | | | | nut driver or socket. Now it is time to decide if you |
| in the opener. Many things can cause this gear to fail. | | | | want to replace the main gear only or the entire |
| Some causes of wear are:o Garage door out of | | | | sprocket or all chain drive models 1984 to present. |
| balance (Springs broke or in need of adjustment)o | | | | Step #12 |
| Chain to tight ao Old ageo Excessive use or high | | | | Skip this step if you are replacing the entire gear and |
| cycleo Factory defect or lack of grease at time of | | | | sprocket or pulley assembly. If you are going to |
| manufacture | | | | replace the drive gear support the driveshaft on a |
| Replacing the large white gear is a low cost, quick | | | | block of wood and drive the lower roll pin/Tension pin |
| and easy do it yourself repair as long as you have a | | | | out with a 5/32" punch. See photo example below. |
| few simple hand tools and follow the safety | | | | Step #13 |
| precautions. These gears can be purchased online in a | | | | Remove and replace the worm gear. In most cases it |
| variety of levels of components. | | | | is not necessary to replace the worm gear unless it |
| Before you get started it is important for you to | | | | shows signs of wear. If you wish to replace this gear |
| have a list of the few simple tools needed to | | | | remove the shaft collar with a 1/8" hex wrench. |
| accomplish this project:o Hammero Half inch wrench | | | | Please be sure to note the location of each of these |
| or adjustable wrench or plierso 3/8" Socket or Nut | | | | components as you disassemble so you can re-install |
| Drivero 1/4" Socket or Nut Drivero 5/16" Socket or | | | | in proper order. When you receive your gear kit, you |
| Nut Drivero Flat Standard Screwdrivero 5/32" Punch | | | | will find there are parts not used in your model this is |
| or similar | | | | because these kits are universal and work with many |
| ~WARNING ~ | | | | models of Sears, Craftsman, Wayne Dalton, Master |
| To prevent possible SERIOUS INJURY or even | | | | Mechanic, Liftmaster, True Value and other brands of |
| DEATH from electrocution, ALWAYS Disconnect the | | | | garage doors openers. Only replace the parts that |
| power cord from your garage door from the outlet | | | | are used on your garage door opener. Remove the 3 |
| before proceeding with any inspection or repair. | | | | nuts that hold the motor to the frame and then |
| Step #1 | | | | remove the worm gear. Install the new worm gear |
| Make sure your garage door opener is unplugged. | | | | making sure the roll pin is properly seated in the new |
| This step insures that no one unintentionally attempts | | | | gear. Re-install other components in reverse order. |
| to open or close the garage door while you are | | | | After you complete this assembly I recommend you |
| working on it or you do not accidentally activate the | | | | lube the worm gear so you do not forget. |
| door while servicing it. | | | | Step #14 |
| Step #2 | | | | Begin reassembly in reverse order. Be sure to |
| Disconnect the door from the outer trolley by | | | | thoroughly lube the main drive gear and that grease |
| manually pulling the red disconnect rope and manually | | | | is on each and every tooth. Attach the gear and |
| close the garage door. | | | | sprocket or pulley assembly to the main chassis with |
| CAUTION | | | | the three 5/16" head screws. Install the assembled |
| The Garage door MUST be in the fully closed position | | | | motor frame to the chassis with the four 5/16" head |
| during all repairs and inspection. | | | | screws and reattach the red, blue and white wires; |
| Assuring that your garage door is closed will reassure | | | | now install the limit assembly and the limit drive gear |
| that your door will not fall or make any movement | | | | making sure they mesh properly. You can now install |
| that would cause injury or startle you. We | | | | the RPM sensor and reconnect wires. Install the metal |
| recommend that once the door is closed that you | | | | cover and end panels, be sure to plug in the circuit |
| clamp the door down using a vise grip or clamp | | | | board and reconnect photo eye and push button |
| above one of the rollers to prevent the door from | | | | wires. |
| being opened from the outside. | | | | Step #15 |
| Step #3 | | | | Reconnect the power cord to the opener and cycle |
| Slacken the chain or belts tension by loosing the | | | | the opener until the sprocket completes a complete |
| tension nut on the garage door opener trolley. | | | | clockwise cycle. The trolley must be in the fully down |
| Typically this is nut and can be adjusted with a | | | | position before installing the chain. Now you can |
| ½" wrench. | | | | remove the tape from the rail and reinstall the chain. |
| Step #4 | | | | The chain and sprocket reference mark should be |
| Remove the sprocket or belt pulley retainer cap. | | | | close to lining up. Tighten the chain so that the chain |
| Usually this has a clip on the back if you press in it will | | | | is ½" above the base of the rail at midpoint for |
| release. | | | | "T" style rails and ¼" for square tube rails. |
| Step #5 | | | | Secure the chain tightening lock nut. |
| I always recommend marking the position of the | | | | WARNING |
| chain or belt to the sprocket prior to removing. This | | | | Note when adjusting and testing your garage door |
| can easily be done with white out, tape or any other | | | | motor it is importantto make sure no one is in the |
| means. This step helps assure that your chain or belt | | | | path of the moving door. |
| gets reinstalled in the correct position and makes for | | | | CAUTION |
| quick and easy reference if needed later. Remove | | | | It is important to know when testing your garage |
| the chain or belt from the sprocket and then slide | | | | door opener it is possible to over cycle the motorand |
| the inner trolley to the closed position until it engages | | | | have the motor temporarily overheat and stop |
| the outer trolley. Place loose chain/belt on the end of | | | | operating. |
| the rail closest to the sprocket. I typically duct tape | | | | To prevent this try and not operate the door opener |
| the chain to prevent it from falling to the floor and | | | | more than 10 cycleswithout giving it 5-10 minutes to |
| getting all twisted and dirty. | | | | cool off |
| Step #6 | | | | Step #16 |
| It is now time to remove both end covers and the | | | | Now run the opener and test to see if the door |
| main housing. The end cover are each attached by | | | | opens to the correct position and closes to the |
| three or four ¼" head screws that can be | | | | correct position. If you need to make adjustments |
| removed with a ¼" nut driver or socket. Be | | | | use the travel adjustments screws to make fine |
| sure to unplug the wire to the circuit board. | | | | adjustments. I recommend only making slight |
| Step #7 | | | | adjustments ¼ turn or less at a time. For |
| Remove the retaining clip and the drive gear for the | | | | reference one full turn of the screw equals approx 2" |
| limits. Also at this time remove the limit switch | | | | of travel on ½ and ¼ HP models and 3" |
| assembly by squeezing the sides just below the | | | | on ¾ HP models. |
| bracket by the drive gears. There is no need to | | | | Step #17 |
| disconnect the wires as it is ok to leave this limit | | | | Once you have your doors travel adjustment correct |
| assembly hang by the wires. Do not make any | | | | it is time to adjust the force. This is the pressure |
| adjustments to the limit assembly screws, this will | | | | that it takes to assure your door opener will operate |
| insure that there is minimal adjustment needed to the | | | | safely. The first step in this process is to check the |
| limits after you complete your repair and run your | | | | down force. With the door open simply activate the |
| garage door opener. | | | | garage door opener and when the door reaches the |
| Step #8 | | | | half way point grasp the door from the bottom and |
| Now its time to remove the RPM sensor this can be | | | | try and stop it. If the door is hard to stop or does |
| easily done by unplugging the wire harness and | | | | not stop decrease the down force adjustment in |
| remove the RPM sensor from the securing tabs. | | | | small increments until it reverse upon reasonable |
| Step #9 | | | | force. If the door does not close and the light begins |
| Disconnect the red, blue and white wires from the | | | | to blink increase the down force adjustment in small |
| motor. It is important that you note where these | | | | increments until you can check the reversal at half |
| wires go. The same color wires go to the same | | | | way. Adjusting the force does not guarantee that |
| terminals on the capacitor red/red and blue/blue. | | | | your operator will reverse on 1-1/2" object at the |
| Step #10 | | | | floor. For more information on adjusting the reversal |
| Remove the four 5/16" hex head screw's that hold | | | | at the floor see your owner's manual or call the |
| the motor assembly to the frame of the garage | | | | manufacturer. |