Repair a garage door opener?

In alt.home.repair on Tue, 31 May 2005 16:25:17 GMT bart posted:

I knew a homeowner who tried that. He's only 3 feet tall now.

Meirman

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Well, just took it off. The large white plastic gear is chewed up. The model number opener is 41A5021-1B On the gear it has 81B0045.

How do you tell if it is balanced or not?

Stays put about halfway up. No more than 5 or 10 lbs down force at the bottom of travel.

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.

I can lift and lower it with no strain. I think it is balanced. I have had no problems. This gear lasted 7 years.

Sounds like stripped out plastic gears... probably still available at your local garage door man's shop. Ken.

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.

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 fully closed.

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.

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 adjustment instructions.

I ordered the part here:

On 5/30/2005 9:33 PM US(ET), snipped-for-privacy@hotmail.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)