Craftsman 1/2 HP garage door opener - Chain keeps hanging loose.

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Old 11-15-11, 10:05 AM
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Craftsman 1/2 HP garage door opener - Chain keeps hanging loose.

Hello all,

New here and got a problem.

So I have the Sears craftsman 1/2HP garage door opener. It's an old model that was installed 15 years ago.

Here is the problem. A few weeks ago the chain was hanging loose, about 2 inches below the rail and was rubbing on the rail. This would not allow the door to close properly. As soon as the garage door closed, it would automatically open back up. So I tightened the chain using the bolt as shown on the pic below


I tightened it to the point where there would be 1/2" space between the bottom of the rail and the chain. This is by the original manual specs. This seemed to fixed the problem and the garage door would open and close with no problem. However, a week later I found the chain hanging 2 inches below the rail again!!! So I did the procedure again and it worked for 2 days. Yup, two days later the chain was hanging loose again. What gives?

Any help would be appreciated.

Thanks.
 
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Old 11-15-11, 11:11 AM
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First, welcome!
Regarding your question:

The 3 things I'd look at/ think about:

1) Is the "bolt tightening" coming loose, due to vibration, no lock washer, bent fitting,etc??
I'd suggest re-tightening the bolt, and somehow marking it/take a picture with a ruler??,somehow have a record of where the hardware was. Then, if the chain hangs loose again, you'd have a reference to check, to see if the bolt/nut etc. is causing the problem.
If the bolt tightener is in the same situation if/when the chain becomes loose again, then the cause is elsewhere.

2) On my openers, each end the chain is connected to a cable, which completes the loop. Is it possible that the cable part of the chain loop is coming loose, (stretching???) causing the sagging??

3) Was the chain loose when the door was closed, as well as when open?
Can you watch as the door cycles closed/open, to see what/why/how the loose chain is causing the door to reopen after closing?

good luck, let us know how things develop.
 
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Old 11-15-11, 11:33 AM
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The first thing I thought the problem was is the bolt itself. Like you mentioned, I did mark it with a marker to see if the bolt/nuts change position after a few cycles. But the bolt stays in the same position when the chain becomes loose.

My chain is also connected to a cable to make a complete loop. It does not seem to be stretched and is not loose.

The chain is loose when the door is closed, but is tight when the door is open. I've watched it close and open a few times and just can't see what causes it to hang once the door closes.

Can this be caused by the travel limiters or UP/DOWN force adjusters? Do I need to play with those and see if they simply needs to be adjusted?
 
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Old 11-15-11, 01:43 PM
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The chain on your opener is just like the chain on a bicycle. When you are pumping the bike, the bottom part of the chain hangs loose. When you put the brakes on the top part of the chain hangs. If you watch the chain on your opener one side hangs in the up direction and the opposite side hangs going down. Now is a good time to take a look at the sprocket on top of the motor unit. It has a bronze bearing that wears over time and lets the sprocket lean forward. This could be causing your chain to seem to have grown. When it gets bad enough it will throw the chain off the sprocket altogether.
 
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Old 11-15-11, 02:44 PM
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Thanks for the reply. Went and checked on the both sprockets (one on top of the garage door and one on top of the motor). The sprockets look good, no leaning or anything.
 
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Old 11-15-11, 08:07 PM
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I give up. It's to the point now where I'll tighten the chain up, try to open the garage door, it will now only open halfway and stay like that. When I hit the button to close it, it will close and the chain will sag right away. I took the cover off the motor and didn't see any obvious damage to any of the sprockets. Is a belt driven unit any better/quieter? This thing jerks and makes all sorts of loud noises. I think it's at the end of it's life.
 
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Old 11-16-11, 05:47 AM
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Belt drives are very quiet, but IMO they just replace the chain and sprockets with a belt and pulleys. No lube required, but that's the only advantage I see. The belt is still exposed and IIRC it uses a similar cable and bolt attachment. That's from the few Chamberlains I've messed with. Might be different styles.

I like Genie screwdrive openers.
 
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Old 11-16-11, 07:08 AM
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It now sounds like your door is traveling too far in the down direction and your 'down limit' and 'down force' adjustments have been misadjusted. The belt drive by both Genie and Chamberlain are the top of their models. They are quieter and smoother. I'm not sure about Genie but Chamberlain uses a D.C. motor which is smoother and the opener was designed for quiet operation from the ground up.
 
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Old 11-17-11, 07:21 PM
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Never met a chain-drive door opener that I liked. Noisy, finicky, dirty, etc. Install a good shaft-drive Genie, and forget about it (other than a dab or two of white grease on the shaft every year).

After 15 years, yours doesn't owe you anything.
 
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Old 07-13-14, 02:14 PM
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Craftsman 1/2 HP garage door opener - Chain keeps hanging loose.

So many different answers to this problem, that it started my head spinning.
I am NOT a garage door opener expert. I am a retired accountant.

I had the very same problem recently. I have been using this opener for over
30 years. It's a good one.

Logic told me that if I have to keep adjusting the chain to take up the slack
that it must be getting stretched!

A close inspection of the wire showed me that it is in fact starting to fray. If
not replaced very soon, it will snap and will come down with the chain, more
than likely when one or both our cars are under thereby causing expensive
roof damage.

I've ordered a new chain/wire kit from Sears. It's only 50 bucks. Cheaper than
a car paint job. Meanwhile, I am inspecting the wire daily until I get the replacement.
 
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Old 07-13-14, 05:37 PM
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A 30 + year old unit. What will fail next? You are frugal to the max.
 
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