my garage door opener quit

[LCHIEN]

The motor hummed but nothing moved. Had the opener installed for 17 years. Sears chain drive.
Opened the housing and it was obvious, there was a pile of white dust in the lower cover and the drive gear driven by the worm gear off the motor was completely worn away... more dust and debris on the bracket.

Why the **** did they use plastic (looks like nylon) gears? This thing probably would last 100 years with metal gears.

Anyway, 35 bucks plus shipping for replacement gear shaft and sprocket assy, in the mail now. Just hope I can get at it to do the repair.

[Uncle Cracker]

I think the nylon gears may be because they supposedly don't require much lubrication. But nylon has its own problems. I think you are fortunate to have gotten 17 years out of them...

[geopilot]

This seems to be a very common failure for the Craftsman/Chamberlain/Liftmaster chain drive models- mine just did the exact same thing. I got 12 years out of mine, and was also shocked that they use a plastic gear. I decided to replace just the plastic gear- fairly easy job. Lots of parts on ebay. Make sure you grease the new gear. Here is a nice how-to web page:
http://www.stardoorparts.com/How_to_...gears_s/30.htm

[cabinetman]

Why plastic/nylon?...well because it's called planned obsolescence.
.

[drillman88]

Just be glad you can get the parts. I went through the same thing with a Wayne Dalton last year. Parts were back ordered for a month. I ended up buying a new opener for a $15 part. SWMBO let it be known a month was to long.

[woodturner]

Why the **** did they use plastic (looks like nylon) gears? This thing probably would last 100 years with metal gears.

I'm assuming, like most people, that you never lubricated the gear? That's why they use nylon - longevity. A metal gear would have failed far sooner, if not kept lubricated. A metal gear if kept lubricated could have lasted 17 years, but without lubrication probably less than five years.

So the short answer is that most people won't maintain the product, so they build the product to last under "real world" use.

You got 17 years out of a product with an expected life of 5 years, and it requires only a simple fix to repair. I wouldn't complain about that.

BTW, newer openers are much more immune to false activation (i.e. the door opening from a stray signal). If you are concerned about security and your opener does not have "rolling codes", it might be prudent to replace it.

[LCHIEN]

This seems to be a very common failure for the Craftsman/Chamberlain/Liftmaster chain drive models- mine just did the exact same thing. I got 12 years out of mine, and was also shocked that they use a plastic gear. I decided to replace just the plastic gear- fairly easy job. Lots of parts on ebay. Make sure you grease the new gear. Here is a nice how-to web page:
http://www.stardoorparts.com/How_to_...gears_s/30.htm

Thanks Geopilot, that's exactly the info I need to do the job... I was thinking I'd have to feel my way around. I see a couple of time saving hints there that will be useful.

wish i'd thought to search for that before i ordered parts... could have saved 5 bucks. Apparently very common parts. One of the advantages of buying sears stuff.

[phrog]

Had exactly the same problem with mine last year after about sixteen years of use. I went to the local Sears Parts Center and when I told the young lady working there that I needed a part for my old Craftsman garage door opener, she handed me a box with all the needed parts before I could explain what was wrong. "Is that what you need?" she asked. "Yup, but how did you know so quickly?" "We sell a ton of those," she responded; "Gear wears out." I was told by an installer to be sure to use the entire small tube of grease that came with the kit or I would be back shortly for another kit.

PS I also replaced a worm gear and bushing. They were included in the kit and I figured they were pretty worn also.

[dbhost]

I think you answered your own question... Why on earth would a manufacturer sell you a product to last 100 years when they can sell you and your descendents 6 of the same products in that time...?

[phi1l]

Also, you might want to check the garage door spring tension. If the spring tension is too tight or too loose the garage door opener may be having to work too much & is there for putting more stress on the gears than necessary.

Although I don't think you can complain too much about a garage door opener lasting 17 yrs.

[mpc]

Plastic/nylon gears, besides being more tolerant of poor lubrication, are also used as mechanical fuses in many devices. Garage door openers (GDOs) have a "door is blocked" sensor of some sort (so it doesn't close on a child's head and crush it) but many folks mis-adjust those out of ignorance or to make up for a poorly balanced/sprung door. If the door does jam or is blocked, a mis-set safety sensor would not activate... the GDO motor would run & fry. Instead, this sacrificial plastic gear gets chewed up.

A similar gizmo exists in clothes washers: a plastic disk with fingers sticking out of it on both sides. It looks like somebody glued together 2 Barbie Doll scale patio tables or 2 of those little plastic standoffs used in delivery pizza boxes. The fingers fit into the motor drive on one side and into the gearbox/tub on the other. If the gearbox jams, if clothes jam the actuator, etc... you'll get a white plastic snow pile instead of a fried motor. Sears parts/repair stores stock these plastic fuse parts for quite a few of their appliances, GDOs, etc. Most are fairly easy DIY replacement jobs if you have any mechanical aptitude; saves a service call.

mpc

[LCHIEN]

Final results

Heres the new gear (left) and old gear (right). The worm drive gear on the motor shaft is a harder plastic and did not seem like it needed replacing.

Replaced it, neede some adjusting as it ran into and jammed on the trolley stop after the replacement. Had to figure out how to unjam it and readjust and now its all OK.