Very common problem is the plastic worm gear/spur gear combo. These *will*
chew themselves out sooner or later, sooner if your door springs aren't
See my page:
The door is balanced when you can lift or lower it with no "strain". It
goes up... It goes down... The springs are set properly to help you lift
it, but not so tight they make it difficult to close it. When it's
closed, it stays closed without needing to be latched, rather than
rolling itself up any amount. When it's open, it's all the way open, and
doesn't tend to "fall shut".
It's all about getting the spring tension correct.
Replace the gear as it is now, and I promise you that it won't be more
than a few months to a year before you have to do it again.
If you've got torsion type springs, I strongly suggest you *DON'T* try
to mess with them unless you *KNOW* what you're doing - They're usually
wound tight enough to break an arm and/or pitch a person off a ladder,
and I've see a fellow lose one of the tensioning bars, and have the
spring fling it across the garage and through the drywall on the inside,
and the particleboard and aluminum siding on the outside, and come to a
stop stabbed about four inches into the trunk of a tree in the middle of
the back yard. When it went by, it made this weird humming/zinging kind
of noise that was spooky as hell.
Don Bruder - email@example.com - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
I've owned two of the Chamberlain units (I think both were Chamberlain, one
definitely was). Second unit made it for about 4 years (balanced door, but
pretty large), first unit did 6 or 7, I think it was. If you go for repair
I'd get a decent worm and worm wheel from Boston Gear or somebody. I went
replace with decent unit, the second time.
On 31 May 2005 18:12:45 -0700, firstname.lastname@example.org wrote:
I replaced the gear and sprocket assembly on my Liftmaster opener over
a year ago. No problems to date. Not a difficult job, though a bit
"fussy." Hardest part was getting the chain back on. Be sure to read
and understand the manual and replacement kit installation and
I ordered the part here: http://www.1stdooropeners.com/index.html
And while those torsion springs can certainly maim someone who doesn't
know what he's doing, the tension type springs can injure an "inncent
bystander" who happens to be under one when it breaks loose and flails
around before coming to a rest, usually dangling down by one end.
I had one bust while I was still in the garage waiting for the garage
door to close before opening the door to the house, a strategy I have to
employ to keep our stupid cat from escaping. The BANG was enough to
rattle my teeth, and as the break was at the back end, the spring flung
forward and knocked a hole in the drywall above the door.
That's when I learned about the safety cables which our builder failed
to take care of having installed. When I replaced the tension springs on
that door I added safety cables through the centers of both springs to
restrain them the next time one breaks. Premade safety cable sets were
so cheap at Sears that I didn't even bother to DIY them myself with wire
cable and clamps.
I heartily encourage taking a peek at those tension springs if your
door(s) use them and adding safety cables if needed. For all I know they
may be code required some places, as I think they should be.
Oh, BTW, a tip which might help someone needing to replace garage door
tension springs themselves. I didn't know what strength springs to buy,
and had to measure the downforce weight of the garage door when nearly
I only had a bathroom scale and it bottomed out when placed under the
door. I grabbed a hunk of 2 by 4, a brick and a yardstick and quickly
set up a 1:3 lever system so the scale received only 1/3 of the force of
the door pressing down on the 2 by 4 at a point 1/3 of the distance from
the brick to the scale. That worked as Archemedies would have predicted,
as did the springs I bought based on multiplying the scale's reading by 3.
I wrote the spring ratings on the inside of the door to save me or the
next owner of the place from having to go through that exercise again. <G>
On 5/30/2005 9:33 PM US(ET), email@example.com took fingers to keys,
and typed the following:
I had the same problem on a 20 year old Craftsman door opener (made by
Chamberlain). In my case it was the nylon drive gear was stripped of
teeth. Got a replacement at the Sears repair outlet. Part # 41A2817.
Drive Gear and Worm Set. $20.99 (US)
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