spring maintenance (torsion spring)

Last week the garage door torsion spring snapped. It was at least twenty-five years old and no one lamented it's short life. So a
day or two later we got the spring replaced, and a new garage door opener for good measure. The door is wood, single car sized, and quite heavy. I don't have any specs, but the spring is clearly metal, so here I am.
I was not there when the installer was, but I was told he recommended oiling the spring with WD-40 every three months. Now, to me "oiling" and "WD-40" are not the same thing, but I can see people confusing them.
I can see two theories behind why you'd want to oil the spring: 1) a light coat of thin oil will keep it from rusting; and 2) as the door opens and closes, the tension put on and released from the spring causes it to rub against itself.
With the previous install, the rollers were occaionally -- perhaps yearly -- lubricated with white lithium grease but that's it. At the end of the life of the old spring, it had a small amount of rust, but I don't think it caused the spring to fail early. Nor did the spring look like it had worn down much, so I'm not sure the rubbing action is very significant.
So what should I plan on doing?
Elijah ------ even if this isn't metalworking, it's metal
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He wants to sell another job, so WD-40 is the recommendation. You don't want rust, pits will start fatigue cracks in that highly stressed spring. I don't think friction between the coils would cause that much fretting wear. I would probably use LPS 3 for coating the spring if I lived in a really humid area, a good grade of automotive grease would probably work most any other place. Repeat if it shows bare metal.
WD-40 probably wouldn't hurt that much but it's sure not either a lubricant or a rust preventative. Maybe he's depending on the brown crud buildup to shield things from moisture.
Stan
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On Mon, 21 Nov 2011 20:27:40 -0800, stans4 wrote:

I knew a guy who used to be a systems engineer* for an aerospace company. He did lots of interesting things. While you didn't want to get him started on the stories of making side stick controller grips out of condoms and RTV, he did once tell me that he did a _long_ study of WD-40 and found out that it's a water attractant.
It's made to penetrate into cracks, even when they're wet -- so it has stuff in it to disperse into water, and that stuff attracts water (don't ask me what, I do not know).
I'd wipe it down with plain old oil, or if I was feeling really inspired I'd get some of that black crap with moly in it that Christopher was talking about, mix it with some kerosine, and wipe it on. The kero would help it disperse over the spring, then it would evaporate leaving a protective film behind. 30W oil stolen from the lawnmower (before you run it _through_ the lawnmower) would probably be at least as good.
And yes, AFAIK, rust = stress risers, and stress risers = bad.
* In aerospace companies, you get the title "systems engineer" if you're really dumb but energetic enough to be invaluable, or if you're so damn smart that no one knows what you're doing but they know it's invaluable, or both**.
** You have to know guys with PhD's to understand the 'both', there.
--
Tim Wescott
Control system and signal processing consulting
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"Tim" wrote in message wrote:

I knew a guy who used to be a systems engineer* for an aerospace company. He did lots of interesting things. While you didn't want to get him started on the stories of making side stick controller grips out of condoms and RTV, he did once tell me that he did a _long_ study of WD-40 and found out that it's a water attractant.
It's made to penetrate into cracks, even when they're wet -- so it has stuff in it to disperse into water, and that stuff attracts water (don't ask me what, I do not know).
I'd wipe it down with plain old oil, or if I was feeling really inspired I'd get some of that black crap with moly in it that Christopher was talking about, mix it with some kerosine, and wipe it on. The kero would help it disperse over the spring, then it would evaporate leaving a protective film behind. 30W oil stolen from the lawnmower (before you run it _through_ the lawnmower) would probably be at least as good.
And yes, AFAIK, rust = stress risers, and stress risers = bad.
* In aerospace companies, you get the title "systems engineer" if you're really dumb but energetic enough to be invaluable, or if you're so damn smart that no one knows what you're doing but they know it's invaluable, or both**.
** You have to know guys with PhD's to understand the 'both', there.
--
Tim Wescott
Control system and signal processing consulting
  Click to see the full signature.
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Plan on replacing the spring in another 25 years. There is not much you can do to extend the life of the spring. If you do nothing it will last about 25 years. If you oil it or spray it with WD-40, it will last about 25 years.
Dan
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-... -Plan on replacing the spring in another 25 years. There is not much -you can do to extend the life of the spring. If you do nothing it -will last about 25 years. If you oil it or spray it with WD-40, it -will last about 25 years. -Dan
I recently had to replace a broken rusted spring inside my twelve year old car's hood latch that the annual spray of LPS3 didn't reach. The others were fine.
jsw
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I find ordinary [1] bar & chain oil handy. Ultra-sticky so it doesn't readily drain/seep away in intermittenent use applications. It's what I keep in the general-purpose oil can.
And nobody seems to mention Fluid Film(tm). Probably not a great and durable lubricant but is an fair one for low speed and pressure. Protects against rust and is thixotropic so even where it goes on kinda gloppy, it later seeps into crevices and joints in any application where there's ongoing vibration.
[1] No moly. Stuff sold here is red.
FWIW,
--
Michael Spencer Nova Scotia, Canada .~.
/V\
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On Nov 21, 10:37pm, "Stormin Mormon"

My dad had some of that chain lube, was basically aerosol graphite grease. Probably would work OK in this application, if a bit messy to clean off, come the day. Worked well on the snowblower drive chain.
Stan
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On Monday, November 21, 2011 8:11:45 PM UTC-8, Eli the Bearded wrote:

...the installer...

Why fiddle with it every three months? Paint it, or wipe on boiled linseed oil. WD-40 is a better cleaner than protector.
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On Tue, 22 Nov 2011 04:11:45 +0000 (UTC), Eli the Bearded

Here's what I do on my GDO springs:
There is a need to release the tension on the existing spring, so I count the number of turns it takes to release it. I use that to ballpark the turns on the new one/pair. I've never seen the need to oil the spring or torsion rod, so I haven't, and I have never heard a squeak from mine. Spray lithium would work OK, I suppose, and if I used it, I would spray it between the coils onto the rod, perhaps within 6" of the ends, but never on the ends, where you adjust the spring tension. It could make it harder to retain adjustment.
I've never seen a rusted-out or rubbed-through garage door spring, of either style, either, so I wouldn't worry much about it. They usually fatigue.

Youbetcha.
-- Happiness is not a station you arrive at, but a manner of traveling. -- Margaret Lee Runbeck
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