Replacing plastic gear in Lift Master

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  #1  
Old 12-30-04, 03:09 PM
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Replacing plastic gear in Lift Master

I have a 1/2 H.P LiftMaster electric garage door opener (13 years old). Recently, the door stopped opening/closing the door, but you could hear that the electric motor was going. Rather than pay the $100 initial service fee from the local repair guy (plus the $$ to fix the problem, I decided to take a look at it for myself.

I removed the outer cover. Upon inspection its very appearent that the plastic gears are no longer engaging as the larger gear (the gear that is attached to the shaft that goes up to the chain) is worn pretty thin (shavings everywhere).

I do not know how complicated it is to buy a new gear and simply replace it myself. I am moderately competent in this stuff (which means; a normal 1 hour job, usually turns out to be 4 hours and I swear alot).

Any advice would be appreciated. I hate spending $200 for something that might be as simple as changing a lightbulb (perhaps??).

Thanks
 

Last edited by BilinMichigan; 12-31-04 at 07:48 AM.
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Old 01-02-05, 10:41 AM
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Thumbs up I just did this today

I had the same problem on my Craftsman. The Craftsman, the Liftmaster and another brand that I dont remember are pretty much all the same and the parts are interchangable.

I searched eBay and found the parts I needed. If will post the link I used below. I am willing to bet that you can find them on the net with a little leg work too. My part kit cost $30, a far cry from the $129 that the repair guy wanted. They also sell just the gear itself for about $20 but looking at it all, I decided to get the $30 piece.

http://cgi.ebay.com/ws/eBayISAPI.dll...PcY_BIN_Stores

The parts included everything I needed, plus good instructions. The whole process took me about two hours by myself. I am sure that it would have been quicker with some help, and I am not the handiest of men around tools. I unattached the unit from the ceiling mounts and let it rest on a six foot ladder and worked on it that way. This worked well for me.

I did not have to remove the motor assembly, I managed to remove the gear set with a little work just fine. Replacing it was just as easy. You may or may not want to remove the motor, per the instructions.

I had two problems. Be sure to thread the screws in all the parts before you install them, on mine the screws were very tight and pre-threading them once really helped. Second, I labeled the wires on the back of the opener before lowering it to the ladder, so I could put them back in their proper place. But, my labels came off and I had to guess. The opener works fine, the sensors work fine, the remotes work fine but my light wont come on no matter what I try. I am sure its just a matter of wiring and I am looking on this forum for an answer now.

In short, its not a difficult process and I saved a lot of money.
 
  #3  
Old 01-03-05, 04:48 PM
cthoms
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Thumbs up Me too!

I had the same thing happen to my Craftsman 3 days ago and went looking for the solution and found this discussion! I bought the kit (41A2817) from a local shop for $28 cuz I was in a hurry. I only needed the big gear cuz everything else was fine. Threw the rest of the stuff in the trash. The old gear looked like a pile of snow. I didn't lower the unit or remove the motor, just yanked the gear assembly and swapped the gear. Took about an hour. The door man that sold me the kit warned me that although theses are designed to fail, mine shouldn't have failed so soon. He said something else must be out of wack for the gear to fail. I have no idea what it could have been cuz I've checked everything. Guess I'll be replacing gears every few years.

Be sure to clamp the chain in position before removing it from trolley. Be sure to orient the new gear on the shaft the same as the old one. Be sure to orient the gear assy the same way it came out or that plastic guard won't go back on.

Shoot me an email if you have any questions.

<[email protected]>

Ref: 1/2 HP Craftsman chain drive garage door opener.
 
  #4  
Old 01-03-05, 05:31 PM
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for future referance there is a complete shaft assembly, with all needed gears, sold. part #41C4220A. Much easier to replace the whole assembly than replacing a gear and sprocket.

Chamberlain, Liftmaster, and Craftsman all use this assembly on their chain machines.
 
  #5  
Old 01-05-05, 03:54 PM
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Thats what I did..

I ordered the entire assembly and not just the gear. To me it was worth the extra money not having to figure out how to remove the gear from the shaft, and replace it. Much easier and saved some time.

My gear lasted a good ten years with average use.. I hope that this new one lasts as long. The old one was pretty chewed up, and as stated above, I can see how these are designed to fail. Maybe I should have bought two!
 
  #6  
Old 01-23-05, 05:59 PM
yukmail
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okay, so mine broke about halfway up as the door was opening. I replaced the sprocket assembly & gears. I put everything back together in the closed position 'cause that's what it said to do. i hit the button and it tried to close, buckling the support bar, then reversed and came back up a few inches. The light bulb did not flash. So I thought maybe it should be in the same place it broke so I took the chain off & moved the trolly to about where it broke & reconnected the door. I hit the button. It went down about 11 inches (not closing all the way), reversed and went back to where it started. The light bulb did not flash. I disconnected the door & tried it. same thing. the only other thing I can think to tell you is that the green LED light on the back is blinking 5 times in a row, over & over again. it's a sears/craftsman 13953637SRT1. please help.
 
  #7  
Old 01-24-05, 05:45 PM
yukmail
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okay so I got in a hurry and forgot to put the INTERRUPTER CUP ASSEMBLY on the end of the drive shaft. duh. i put it on and then I tried running it through a cycle with the chain disconnected but still only moves 11 inches down and then back. I notice the center limit contact was in the middle, not touching the down or up contact. so I tried moving it to one end, then the other. touching the contact or very near touching. same thing. still green LED blinking 5 times. any ideas?
 
  #8  
Old 01-24-05, 06:51 PM
yukmail
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green LED blink 5 times = RPM sensor error. small wire harness had come disconnectted from RPM sensor, but it was in almost the right place so it was hard to notice it was disconnected. reconnected. ran it once without chain. connected chain. works. finally.
 
  #9  
Old 02-02-05, 10:01 PM
jim70
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Garage Door closed and reversed after replacing gear

I bought the 41A2817 from ebay and replaced the driver gear. When I pressed the remote control the door closed and reversed , but it stopped at half way up. I tried to adjust the up and down travel limit, it did the same thing again and again. It always reversed after hitting the floor and stopped at the half way up. Any advice would be apprecied. Thanks.
 
  #10  
Old 02-15-05, 08:46 PM
sdhager
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Door only opens 1 ft. after Gear replacement

I replaced the plastic gear (41C4220A) in my Craftsman opener and now the door only open travels about a foot (or about 2 seconds) before it reverses the same distance. I have tried without the chain attached to the door, but its the same thing. The chain only travels a foot before it stops and then reverses. Therefore I can rule out the door as the problem.

I know that the up/down limits are adjusted properly, and I have tried adjusting the up/down force from min to max with no success.

There is no infrared reversing system with my opener.

I am completely stumped here. Any help is appreciated.
 
  #11  
Old 02-20-05, 11:25 AM
loro
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Smile Door only opens 1 ft. after Gear replacement

I was having the same problem with a Chamberlain 1100 series.

I also noted while trouble shooting that disconnecting the RPM sensor assembley (41C4398A) did not change the opener's behavior so I figured that the problem might be there.

I was baffled as to how the RPM sensor worked after examining it. It appears to be a simple optical sensor with a LED and a phototransistor in a blade switch type arraingment., like twin towers.

The problem is it is mounted to the side of main shaft.. It looks like nothing can come between the sensor elements. That was when I realized that the black plastic endcap, called an "Interrupter cup assembley (41A2822A), that goes on the end of the motor needs to pass between the sensor tower elements, was not installed.

Putting the endcap back on solved the problem.


Originally Posted by sdhager
I replaced the plastic gear (41C4220A) in my Craftsman opener and now the door only open travels about a foot (or about 2 seconds) before it reverses the same distance. I have tried without the chain attached to the door, but its the same thing. The chain only travels a foot before it stops and then reverses. Therefore I can rule out the door as the problem.

I know that the up/down limits are adjusted properly, and I have tried adjusting the up/down force from min to max with no success.

There is no infrared reversing system with my opener.

I am completely stumped here. Any help is appreciated.
 
  #12  
Old 02-22-05, 01:11 PM
sdhager
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It turns out the problem was with my RPM sensor.

I had the interrupter cup assembly properly attached, and it was passing through the two diodes of the RPM sensor. After closer examination of the sensor I noticed that one wire connecting a diode to the RPM circuit board was broken.

I guess it got damaged when I disassembled it to replace the plastic gear (41C4220A).

I replaced the RPM sensor board and now everything is up and running. Thanks for the help.
 
  #13  
Old 11-01-07, 08:01 PM
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RPM sensor

I'm having the same problem described in this thread. Troley moves like 8" stops and returns, 5 flashes in the alarm led. So believe I may have damaged the LED in the RPM sensor.

Do you remember seeing the LED in the RPM sensor actually light? I'm asking this because I can't see any light come out of mine.

Let me know, thanks
 
  #14  
Old 11-04-07, 09:39 PM
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No it does not lite up. It uses an infra-red wave of light. Cannot be seen by the 'normal' human eye.
 
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Old 01-03-08, 05:06 PM
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"Snow" all over inside motor housing...

First if all, I'm not mechanically inclined whatsoever! I've read this thread and this does seem to be my problem. I have shavings from the plastic gears in my Craftsman 1/2 horse. I kind of pryed on the sprockets with a screw driver and it worked for awhile but now it seems to be done!!! If someone has the patience of "walking" me though this, I would be so greatful! I really can't afford to pay a "door man" right now, so if it's possible I would like to try and fix this myself. Thankyou!!!

Jeremy
 
  #16  
Old 01-19-08, 06:44 PM
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Sorry for the late reply...

My story: I had to replace my gear and sprocket because one of the large springs over the garage door had broken and I didn't notice soon enough... (there were plenty plastic shavings from the gears)

Hence, I would conclude that to see shavings in the plastic gears is a symptom of your garage door forcing them when opening/closing.

I would check for the following:

1) Do your springs look ok? Do they look exactly the same?
BTW: If one spring is broken you will have to replace both (this task is not easy and a bit dangerous)

2) Is your chain too lose or too tight?

3) Is something preventing the trolley from moving smoothly?

Look for other signs that would force the operation of your garage door. Let me know how it goes.

Good Luck.
 
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Old 01-20-08, 12:47 PM
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If you notice I posted a question with a Lift Master also. I replaced the exact gear you're describing and now am waiting for someone to help me further after the replacement as the door does not work right. As for the big white gear, you need to take the unit out first. Disconnect from power, remove two thick screws attached to the very top of the unit and two more bolts on the sides. Loosen the chain using the adjustment bolt on the chain itself and remove the chain from the shaft. Then you remove the "shaft" piece with the gear by removing 4 screws I believe, two of them are accessible from inside the compartment (describing from memory here). Once all screws holding the shaft are removed, you have to release a small plastic retainer at the very bottom of the shaft then pull whole shaft/gear assmebly straight up. Good luck.
 
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Old 01-25-08, 03:06 PM
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What's not working?

What is your garage opener doing? Does the trolley move at all? Do you get alarms? how many LED blinks?
I really struggled to fix miine but at the end it worked so I learned a bit in the process. I need more information on what's wrong with your garage opener to be able to provide some advice.
 
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Old 02-02-08, 04:30 PM
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Please help with garage door opener gear replacement

Please tell me how exactly to yank the gear? from the top?


Originally Posted by cthoms View Post
I had the same thing happen to my Craftsman 3 days ago and went looking for the solution and found this discussion! I bought the kit (41A2817) from a local shop for $28 cuz I was in a hurry. I only needed the big gear cuz everything else was fine. Threw the rest of the stuff in the trash. The old gear looked like a pile of snow. I didn't lower the unit or remove the motor, just yanked the gear assembly and swapped the gear. Took about an hour. The door man that sold me the kit warned me that although theses are designed to fail, mine shouldn't have failed so soon. He said something else must be out of wack for the gear to fail. I have no idea what it could have been cuz I've checked everything. Guess I'll be replacing gears every few years.

Be sure to clamp the chain in position before removing it from trolley. Be sure to orient the new gear on the shaft the same as the old one. Be sure to orient the gear assy the same way it came out or that plastic guard won't go back on.

Shoot me an email if you have any questions.

<[email protected]>

Ref: 1/2 HP Craftsman chain drive garage door opener.
 
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Old 03-15-08, 04:55 PM
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liftmaster door doesn't work after gear replacement

we changed the gears that were stripped. we had the door working somewhat, at one time the door wouldn't shut all of the way,fixed that, then wouldn't open all the way, fixed that, pushed the button, nothing. let sit, would open only couple of inches, then sit. sometimes, it makes a little clicking noise and nothing else happens there is a green light flashing on the back part of the unit. what now?
 
  #21  
Old 03-17-08, 05:06 PM
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I had to replace mine and my wifes at the same time. Have some patience and things will go somewhat smooth. Read the directions a couple of times. Man , if I can do it, you can.
 
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Old 02-12-09, 05:01 AM
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I was having the same problem as many have mentioned here and it started when I replaced the drive gear. The opener will go down about a foot and then reverse. I was getting 5 blinking lights and so I replaced the RPM sensor. It worked for 3 days and now it's doing it again. Any other ideas?
 
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Old 02-12-09, 02:26 PM
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beigledog try this. Make sure the black cup is on the end of the motor shaft and that it is pressed all the way on. Make sure the rpm sensor is plugged in. If neither of these are the issue then you probably did not have the motor shaft pushed all the way back when you tightened the coupler after replacing the worm gear. Loosen that coupler and from the front of the motor (opposite end in which the coupler is on) push the shaft back as far as it will go. Hold it there while you tighten the coupler back up and then try it. Let us know.
 
  #24  
Old 02-12-09, 02:42 PM
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Originally Posted by beigledog View Post
I was having the same problem as many have mentioned here and it started when I replaced the drive gear. The opener will go down about a foot and then reverse. I was getting 5 blinking lights and so I replaced the RPM sensor. It worked for 3 days and now it's doing it again. Any other ideas?
Check the motor shaft as it starts up if there is too much play forward to back it will trip the rpm sensor. (if you took that apart to replace the gear you might not have got it set quite right) Check your down force on the circuit board it may need an increase.
 
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Old 02-12-09, 04:00 PM
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I may have missed a reply that covers this, but I will say it anyhow. The gear at the bottom of the shaft drives the up/down travel switch mechanism. If that gets out of sync, which it usually does, since the chain and the gear train are removed, you need to get that back into close sync or you will spend days getting your travel adjustments right. If I recall correctly, run the trolley all the way down(trolley at the door), rotate the switch drive so the switch to the right(looking toward the door) is just breaking, reinstall the bottom gear. You should now be close enought to make minor corrections with the thumb screws.
 
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Old 02-14-09, 09:46 PM
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Originally Posted by Donald_ View Post
beigledog try this. Make sure the black cup is on the end of the motor shaft and that it is pressed all the way on. Make sure the rpm sensor is plugged in. If neither of these are the issue then you probably did not have the motor shaft pushed all the way back when you tightened the coupler after replacing the worm gear. Loosen that coupler and from the front of the motor (opposite end in which the coupler is on) push the shaft back as far as it will go. Hold it there while you tighten the coupler back up and then try it. Let us know.
I'm having similar issues. I was proud of myself for a minute or so when I realized I had not plugged in the rpm sensor and caught it, but it didn't seem to help in the long run. My issue, after replacing the gear kit is that the GDO cycles for a couple of seconds and then reverses without appearing to turn the gear at all. As I think about the order I replaced shaft bearings I may have blew it because I couldn't fit one of them back in the order they came out. Of course by that point I wasn't sure if I had made a mistake about the order of the shaft bearings and didn't think much of it. Your note above jogged my memory. I'll tear it back down in the morning and try to push the shaft back as far as it will go. If it turns out after reassembling properly the shaft doesn't turn will I be looking at replacing rpm sensor or maybe the motor?

Thanks.
 
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Old 02-15-09, 11:50 AM
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The first thing to look for is the motor shaft moving and causing the black cup to shift on the shaft. This will cause the motor to reverse because it is not riding in the RPM sensor as it should. It isn't the motor causing this problem. Could be a bad RPM sensor but I'll bet on the first thing.
 
  #28  
Old 02-15-09, 03:20 PM
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I looked and the motor shaft wasn't moving at all. I tried to reseat various parts this morning with no luck. I was concerned about the motor because the GDO was cycling for a couple of seconds in each direction before I realized the gear was toast. I removed the cover to my other GDO to confirm that I had put things back together correctly and both matched. I greased the other gdo while I had it open since I had never done it in the 5 years I owned the house and I'm positive the prior owner hadn't done it in 10 yrs....

I gave in and tore the gdo back down, cleaned the parts again, put it back together and tada, everything works properly. A couple of minor adjustments to the garage door and we were back in business. A few minor glitches but all in all not bad considering I barely have opposable thumbs. Thanks for your help.
 
  #29  
Old 04-19-09, 12:41 PM
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I just ordered the gear replacement shaft. Is their any prep work I can do before the part arrives, like removal of the shaft. Can you please provide the steps necessary.
Thanks

Joe
 
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Old 04-20-09, 04:16 AM
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Joe, there are detailed instructions with the gears. I just followed thier directions and it went fine. Good luck
 
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Old 05-19-09, 09:14 AM
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Hi:

I just wanted to let you know that you can in fact buy the gear and sprocket kit and change it, nevertheless if you really want to save money try buying the main gear by itself. You can buy it with the lubricant for $12. Here's some links where you can buy them from. There're a lot more but this work great.
LiftMasterGear: garage door openers- gate operators- gate opener parts- access controls systems
Generic Liftmaster/Sears/Chamberlain Drive Gear Kit Model Number GDG-1
Pro Door Parts: Wayne Dalton Garage Door Parts, Openers, Springs, Keyless Remote Controllers
Hobbit Garage Door Opener Parts
 
  #32  
Old 01-09-10, 04:36 PM
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Here are installation directions for 41A2817

Hope this helps someone. I installed one of these today and i think the below will be better than trying to follow the manufacturer's guides....thanks..Jay

Replacing Sprocket (also known as the drive gear) # 41a2817

As of 1-9-2010

I promise you, if you take 120 seconds to read the below and THEN start working on the door opener your life will be easier and fewer curse words will be heard by neighbors!!

The below assumes you are only replacing the big white sprocket..part 14a2817..if you have the other couple of parts that go on the shaft you’ll easily figure that out after reading the below and seeing the sprocket shaft after you take off the outside of the motor housing.

Some people think you should loosen the MOTOR rather than take out the sprocket shaft!!..No way, I’ve done this 3 or 4 times over the last 20 years, including today, on the doors at my house and the best way is to take out the sprocket shaft like below! (Partly because it is often HARD to get the pin out of the shaft! If you can get the pin out of the shaft WITHOUT taking the shaft out of the motor housing that will be great. I did that the FIRST time I replaced this sprocket but the pin is harder to get out the second or third time (my openers are now 21 years old and still going strong!!)

You do NOT have to loosen the motor NOR take off the limit switch (the screws that set the distance for up and down of the door) Just follow the below

Sprocket alone costs about $9…..if you buy the kit that comes with the other worm gear and pins, etc it runs about $14

Tools…
-1/4 socket on end of screwdriver works well
-Small hammer
-5/16 socket on end of screwdriver works well
-probably a 5/16 socket or wrench to get at one screw inside the motor housing
-socket punch…big enough to NOT damage the pin when u knock it out of the shaft
-probably your reading glasses if you are over 45!!
-your wife, to read you these directions if you are too stubborn to read them yourself as you work!

-Unplug the power cord……….duh!

-bring the garage door all the way closed if not yet closed. You might need to pull the emergency rope assembly to detach the door from the assembly…..don’t loosen the chain to do that..Close the door and leave the garage door catch assembly wherever it stopped when the sprocket died, (hopefully it died when the door was all the way down!)

-loosen the nut on the chain to provide slack in the chain so that u can remove the chain from the sprocket on top of the motor.. (if there is a plastic cover that covers up the sprocket, remove that first of course!)

-remove the metal motor cover and don’t lose all those 8 or so screws!
-you’ll see the flywheel is chewed to pieces……...it’s sharp……….be careful

-In the next couple steps, try to NOT spin the sprocket shaft because it will make your life easier, when you reassemble everything, to have it in the same place so the door opens and closes exactly as before!!


-At the bottom of the gearshaft is a little PLASTIC pitchforked shaped pin that holds the small gear in place (it should be perpendicular to the floor…..carefully pull back each side of that little pin and slide it out.
-slide off that small gear at the bottom of the shaft and put it with the pin for later

-unscrew the 3 screws on the inside top of the motor housing that hold the sprocket shaft to the housing and pull the shaft up out of the motor housing. One screw is usually hard to get to!!

-go to your workbench and pop that BOTTOM pin out of the shaft on the bottom of the white sprocket ( drive gear)(this can be a pain, especially if the sprocket has been changed before using the same pin. Don’t bang the heck out of the pin or it will be hard to get through the hole…..take your time!)

-after getting the pin out…slide the other drive gear off…now grease up your new sprocket really well (this is important unless you feel like doing this job a couple months from now when it grinds apart again!) If you have some extra grease, slap it all over that long gear (called worm gear) that this sprocket interfaces with!

-slide the sprocket back on the shaft…..there isn’t a top/bottom of the sprocket…line it up with the top pin

-Put the shaft back through the hole from the top of the motor housing and then slide that little gear back onto the bottom of the shaft and interface it into the little gear that is still in the motor housing…now slide that pin back through the hole in the shaft right through that gear at the bottom of the housing.

-Screw the three screws back into the motor housing to hold the shaft in place..screws go in from inside!

-put the chain back on the sprocket and tighten up the screw on the chain to take the slack out of the chain

-pull up the garage door (if the sprocket died when the door was not all the way closed) and allow the piece of the door assembly that locks into the long chain assembly to lock into place (where the emergency rope is attached to the assembly. You may have originally pulled on the emergency rope to disengage the long chain assembly from the part that is attached to the door)

-Plug in the power and try the door to see if it goes up far enough and down far enough. If it is not perfect, it is because the shaft moved slightly during reinstallation. No problem. Just use the screws on the side of the motor housing that control the UP and DOWN distance until you get it right.

-Screw in those 8 or so screws that hold the cover of the motor housing and you are done!!

-Put these directions inside a sandwich bag and duct tape it to the top of the motor housing….you’ll be glad you did when this sprocket is toast again in a few years!

-Wash your hands and go get an ice cream, you deserve it!!...Jay
 
  #33  
Old 01-18-10, 01:18 PM
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gear assembly

Jay I wish I saw your post Before I repaired mine. your correct in saying you don't have to take the whole thing apart like my directions did!! but now my door only opens 1 ft and goes back down, i tried travel adjustment don't seem to help, I definitely move the gear assembly around when i was lubricating that's probably one problem, here is a few more possibilities:
motor shaft not all the way seated.
chain to loose or tight.
DO you or anybody else have any suggestions??
 
  #34  
Old 01-19-10, 07:00 AM
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Make sure you put the black cup back on the end of the motor shaft and that it is pressed all the way on. Make sure the RPM sensor is plugged in. If neither of these are the issue, then you probably did not have the motor shaft pushed all the way back when you tightened the coupler after replacing the worm gear. Loosen that coupler up and from the front of the motor (opposite end in which the coupler is on) push the shaft back as far as it will go. Hold it there while you tighten the coupler back up and then try it.
 
  #35  
Old 01-30-10, 05:46 AM
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Will this work on my 456?

Hello.

It sounds like I can follow these instructions for my Overhead Door model 456 (you thought I meant Ferrari, didn't you??). Do you think so? By the way, it looks like it's just the helical gear that's shredded, but should I also replace the worm gear to be safe? And they should both be greased??

It's 5 degrees right now, and I can't wait to get started!

Originally Posted by jayfred View Post
Hope this helps someone. I installed one of these today and i think the below will be better than trying to follow the manufacturer's guides....thanks..Jay

Replacing Sprocket (also known as the drive gear) # 41a2817

As of 1-9-2010

I promise you, if you take 120 seconds to read the below and THEN start working on the door opener your life will be easier and fewer curse words will be heard by neighbors!!

The below assumes you are only replacing the big white sprocket..part 14a2817..if you have the other couple of parts that go on the shaft you’ll easily figure that out after reading the below and seeing the sprocket shaft after you take off the outside of the motor housing.

Some people think you should loosen the MOTOR rather than take out the sprocket shaft!!..No way, I’ve done this 3 or 4 times over the last 20 years, including today, on the doors at my house and the best way is to take out the sprocket shaft like below! (Partly because it is often HARD to get the pin out of the shaft! If you can get the pin out of the shaft WITHOUT taking the shaft out of the motor housing that will be great. I did that the FIRST time I replaced this sprocket but the pin is harder to get out the second or third time (my openers are now 21 years old and still going strong!!)

You do NOT have to loosen the motor NOR take off the limit switch (the screws that set the distance for up and down of the door) Just follow the below

Sprocket alone costs about $9…..if you buy the kit that comes with the other worm gear and pins, etc it runs about $14

Tools…
-1/4 socket on end of screwdriver works well
-Small hammer
-5/16 socket on end of screwdriver works well
-probably a 5/16 socket or wrench to get at one screw inside the motor housing
-socket punch…big enough to NOT damage the pin when u knock it out of the shaft
-probably your reading glasses if you are over 45!!
-your wife, to read you these directions if you are too stubborn to read them yourself as you work!

-Unplug the power cord……….duh!

-bring the garage door all the way closed if not yet closed. You might need to pull the emergency rope assembly to detach the door from the assembly…..don’t loosen the chain to do that..Close the door and leave the garage door catch assembly wherever it stopped when the sprocket died, (hopefully it died when the door was all the way down!)

-loosen the nut on the chain to provide slack in the chain so that u can remove the chain from the sprocket on top of the motor.. (if there is a plastic cover that covers up the sprocket, remove that first of course!)

-remove the metal motor cover and don’t lose all those 8 or so screws!
-you’ll see the flywheel is chewed to pieces……...it’s sharp……….be careful

-In the next couple steps, try to NOT spin the sprocket shaft because it will make your life easier, when you reassemble everything, to have it in the same place so the door opens and closes exactly as before!!


-At the bottom of the gearshaft is a little PLASTIC pitchforked shaped pin that holds the small gear in place (it should be perpendicular to the floor…..carefully pull back each side of that little pin and slide it out.
-slide off that small gear at the bottom of the shaft and put it with the pin for later

-unscrew the 3 screws on the inside top of the motor housing that hold the sprocket shaft to the housing and pull the shaft up out of the motor housing. One screw is usually hard to get to!!

-go to your workbench and pop that BOTTOM pin out of the shaft on the bottom of the white sprocket ( drive gear)(this can be a pain, especially if the sprocket has been changed before using the same pin. Don’t bang the heck out of the pin or it will be hard to get through the hole…..take your time!)

-after getting the pin out…slide the other drive gear off…now grease up your new sprocket really well (this is important unless you feel like doing this job a couple months from now when it grinds apart again!) If you have some extra grease, slap it all over that long gear (called worm gear) that this sprocket interfaces with!

-slide the sprocket back on the shaft…..there isn’t a top/bottom of the sprocket…line it up with the top pin

-Put the shaft back through the hole from the top of the motor housing and then slide that little gear back onto the bottom of the shaft and interface it into the little gear that is still in the motor housing…now slide that pin back through the hole in the shaft right through that gear at the bottom of the housing.

-Screw the three screws back into the motor housing to hold the shaft in place..screws go in from inside!

-put the chain back on the sprocket and tighten up the screw on the chain to take the slack out of the chain

-pull up the garage door (if the sprocket died when the door was not all the way closed) and allow the piece of the door assembly that locks into the long chain assembly to lock into place (where the emergency rope is attached to the assembly. You may have originally pulled on the emergency rope to disengage the long chain assembly from the part that is attached to the door)

-Plug in the power and try the door to see if it goes up far enough and down far enough. If it is not perfect, it is because the shaft moved slightly during reinstallation. No problem. Just use the screws on the side of the motor housing that control the UP and DOWN distance until you get it right.

-Screw in those 8 or so screws that hold the cover of the motor housing and you are done!!

-Put these directions inside a sandwich bag and duct tape it to the top of the motor housing….you’ll be glad you did when this sprocket is toast again in a few years!

-Wash your hands and go get an ice cream, you deserve it!!...Jay
 

Last edited by Mama DIY; 01-30-10 at 05:48 AM. Reason: forgot to ask something
  #36  
Old 01-30-10, 01:17 PM
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Replace both gears and grease them thoroughly.
 
  #37  
Old 02-14-10, 06:36 PM
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Any help appreciated!! My 1/3HP Liftmaster chain drive door opened chewed up the plastic gears about 4 weeks ago. Door company replaced same for $146.00 The same problem has just happened again. The opener was installed 14 years ago. The company stated they could install a new door or fix the gears so I opted for the gear fix. The motor works fine and I've checked the rollers on the door to confirm there is no excessive drag on the gears. So what caused the new gear or gears to strip again in just 4 weeks? Should I just buy a new opener for approx $163.00 or is there something else I should check, which may be dragging on the gears causing them to strip? Thanks for any help in advance.
 
  #38  
Old 02-15-10, 03:37 AM
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Call them back, the gear probably didn't get lubed when they installed it. They should warranty it. Also you paid a little too much. that gear should only cost 40 dollars tops plus labor. If they are a good reputable company they will honor their warranty
 
  #39  
Old 02-15-10, 06:59 AM
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Thanks Doorman2722. Before I blame the installer, I'll double check if he lubed the plastic gears? Should there be lub on both the large and small gears? Approx how much? I didn't see any lub at all. This would be a great defense on my part. I agree on the price, a little expensive. I see the replacement parts are approx $32.00 but as you know they charged a diagnostic fee, service call fee, bla bla bla, which came out to $146.00 I even took the back panel off and advised them what I needed, stating "The plastic gears are chewed up". He was in and out in 1/2 hour. The price was still worth not hearing my spoiled wife complaining about not being able to get in the garage!! Thanks again. We'll see what happens.
 
  #40  
Old 02-15-10, 09:07 AM
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Hey Doorman2722, you were right. I called the company today and she stated I'm the 3rd person with the same problem. She doesn't think the kid installed the gears right or neglected to lub same. They will repair problem at no cost. In todays world, that's a shocker! I'm usuall getting screwed from every angle. Man when things go they go. In two weeks it was the 75 gallon hot water heater, then garage door, then the furnace!! What is next. Thanks again for your time and quick response Doorman 2722.
 
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