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Can lubricant actually damage spring steel?

Can lubricant actually damage spring steel?

(OP)
From a couple of automotive replacement spring websites,

Quote:

Grease has an adverse reaction to spring steel which causes the steel to degrade and weaken the spring, so we do not recommend using grease/graphite between the leaves.

If this is in fact true, can anyone explain the chemistry?

jack vines

RE: Can lubricant actually damage spring steel?

Nope - must be from the spring mfg - they want them to wear out!!

RE: Can lubricant actually damage spring steel?

Utter nonsense. Just look at valve springs--running in oil, a lubricated environment. Valve spring failures (fatigue) I have seen are due to nicks, pre-existing seams in the wire and overstress due to improper installation or operating parameters.

RE: Can lubricant actually damage spring steel?

The only explanation I can think of would be that the grease and dust and grit forms grinding paste.

I'll ask in the workshop, we've been building leaf spring cars for 50 years or more, someone will know.

Cheers

Greg Locock


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RE: Can lubricant actually damage spring steel?

(OP)
Thanks for the replies. I don't get it either, but Eaton, a major supplier of springs has on their FAQ: Link

Quote:

Prior to the mid fifties grease was put between the spring leaves, in fact springs of many pre-50 cars were wrapped in metal liners to hold the grease in. Some cars had hollow center bolts with a grease fitting so the springs could be lubed on the car. The idea behind lubing between the leaves was to reduce inter-leaf friction.

Then in the early 50's the type of steel used to manufacture springs was changed to SAE5160 and the practice of lubricating between the leaves stopped.

Grease has an adverse effect on 5160 steel. The chemicals in the grease react with the steel and causes the steel to breakdown.

Take a look at the front springs on the next large truck you see leaning. There's a good chance the power steering unit will be leaking onto the low side spring.

Eaton makes a lot of springs for OEMs and the aftermarket, but is it likely a large truck/heavy equipment OEM would put a SAE5160 spring on equipment where lubricant leaks are a fact of life, knowing it would result in deterioration?

jack vines

RE: Can lubricant actually damage spring steel?

5160 is steel. There isn't anything particularly exotic about it. It has the things that most other steels have in it. There is rather a lot of chromium, but not enough to classify it as stainless.

Grease is applied routinely to all sorts of things made out of steel. In much more demanding environments than between leafs of a leaf spring stack.

Grease is routinely smeared on steel things that shouldn't rust in storage or shipping.

So I'm inclined to call BS.

RE: Can lubricant actually damage spring steel?

Even if the grease had some chemical or soap in it that reacted with or etched the surface of the steel, I can't imagine it having any worse adverse effects than road salt, MgCl, etc. And it would be a surface effect and I can't imaging it penetrating into the spring and degrading it.

And grease and ATF are similar in that they are lubricants, but other than that, quite different; different additives to petroleum products so that annecdote sounds like hokum.

So unless this is a case of SCC due to chlorides, I'm with the BS call.

rmw

RE: Can lubricant actually damage spring steel?

I'm pretty well of the opinion that greases are mostly formulated to protect as well as lubricate steel. While it might hold onto abrasive particles that find there way in there, it also helps keep them out in the first place and reduces the harm they do while there.

I call BS.

Regards
Pat
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RE: Can lubricant actually damage spring steel?

Merely "thinking out loud"...

Does this question possibly arise from the reduced internal frictional damping of a greased leafpack? To illustrate my ignorance, does a standing wave ever occur in a leaf spring if excited in some particular manner? Even if the center (or whatever point) is well damped by a separate damper ("shock absorber")? I just don't know...

RE: Can lubricant actually damage spring steel?

The friction between leaves makes the ride a bit harder but reduces rebound control so the leaf spring loses some of its inherent self dampening effect.

Regards
Pat
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RE: Can lubricant actually damage spring steel?

Here in Massachusetts all the (less than a dozen, probably) busted springs I've seen ( and essentially all the unbroken ones, too) are quite rusty, but worn significantly where the ends of the leaves (leafs) rub.

page 83 here makes it pretty clear how badly rusted steel is impaired.
http://www.timken.com/en-us/Knowledge/engineers/ha...

RE: Can lubricant actually damage spring steel?

Thanks for the Timken handbook, Tmoose. I have the paper version, but it was a little out of date (1983).

RE: Can lubricant actually damage spring steel?

First of all, plain petroleum lubricants will not attack steels. I think that the only problem would have to come from an additive that is corrosive. I think that a lube maker would be crazy to put a corrosive or caustic additive in his product. Three very common additives are Lithium, Molybdenum Disulfide and Graphite. These should not hurt steels.

RE: Can lubricant actually damage spring steel?

Now, add salty water and re-evaluate those lubricants.

Mike Halloran
Pembroke Pines, FL, USA

RE: Can lubricant actually damage spring steel?

Mike, adding salt water to greases generally results in very poor penetration to the metal surface. In other words, greases and oils tend to repel water. This is fairly well known. Conversely, adding salt water to bare metals has an accelerated corrosive effect. This is also fairly well known.

RE: Can lubricant actually damage spring steel?

I think from some vague memories that greases are typically soaps or metal salts of large molecule organic acids that are mixed into a paste with fine clays.

I guess if a metal was used it could dissociate and form a galvanic cell with the iron or more likely some other component of the steel alloy, however the reactive metal would be the sacrificial one and this (having the metal in the grease being the sacrificial one) would certainly seem to be an objective when formulating grease. Anyway, from my experience, grease protects rather than corrodes metals.

Regards
Pat
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RE: Can lubricant actually damage spring steel?

Pat, Petroleum greases are heavy hydrocarbons mixed with soaps.
The additives I mentioned are non-reactive with steels, as they would have to be in order not to corrode the metal surfaces. In other words, they would be no good if they reacted with the metal and would be anathema as a lubricant additive.

RE: Can lubricant actually damage spring steel?

Despite the source, the careless wording of the recommendation suggests it may be single tech service engineer repeating 'conventional wisdom'. After all, there are a host of different grease chemistries- some even non-petroelum- and if ALL were deleterious to 5160 steel it would be far too fragile to use in the application. Furthermore, power steering units normally are filled with hydraulic oil, so if that (as the FAQ claims) is also harmful why isn't exposure to petroleum in general (including engine oil and tar from the road) recommended against? It sounds a little apocryphal.

RE: Can lubricant actually damage spring steel?

Claiming grease has an "adverse chemical reaction," why then also suggest to avoid using graphite in the same sentence? Does graphite have an "adverse chemical reaction" as well? Power steering fluid too? Any lubricant, solid or liquid, ever?

There must be a mostly mechanical answer. Lubricants decrease the friction, maybe the spring operates at a lower temperature and fatigue characteristics are worse. Maybe it is more prone to "sag" when it sits at rest because interleaf friction is much lower. I'd buy that actually.

"It just doesn't work and we don't know why" can be explained by black magic, or 99% of the population will also accept "an adverse chemical reaction" because they don't know the difference between the two.

A lot of people know that a lot of things "just don't work" and for most, "that's how everyone does it" is a good enough explanation. For engineers it is not.

But everyone knows mechanical engineers hate chemistry, so points for effort on this one.

RE: Can lubricant actually damage spring steel?

Graphite and iron do experience strong galvanic corrosion in the presence of salt water. A mitigating factor is that it is difficult to maintain electrical contact between iron and graphite particles as corrosion occurs.

RE: Can lubricant actually damage spring steel?

Compositepro, iron already experiences strong corrosion in the presence of salt water, so what is the role of Graphite here? Also, we are talking about a steel that is a near stainless steel. Some chemical environments corrode stainless as easily as non-stainless steels. Does graphite cause stainless to corrode more readily than non-stainless or is it simply that it reduces the corrosion resistance of stainless to that of ordinary steel?

RE: Can lubricant actually damage spring steel?

It's all a matter of details. A piece a graphite connected to apiece of iron so a current can flow from one to the other, will form a battery in salt water. The iron will be gone in hours with hydrogen bubbles at the carbon. Of course, steel is an alloy of carbon and iron.

RE: Can lubricant actually damage spring steel?

I have been lurking reading these post. & I find the manufactures comments amusing.
the only way the grease could effect the 5160 steel if some contamination was to be found in the grease.
thus causing some type chemical reaction.

Example would be faulty manufacturing of the grease it self, but I really don't see that as a possibility.

Mfgenggear

RE: Can lubricant actually damage spring steel?

mfgenggear, what I'm getting is that although plain grease shouldn't be a problem, grease with graphite -a very common type- might be damaging in regions where road salt is used and 5160 MAY be more susceptible than other steels. I had not heard this before, but that's not a surprise.

RE: Can lubricant actually damage spring steel?

Thats funny, Remember when you could buy oil with graphite, I use to use that stuff in my car when I was a youngster.
I must have easily achieved 300000 miles, :>)

any way it's possible but I don't believe it would. :>)

Mfgenggear

RE: Can lubricant actually damage spring steel?

That would be Arco graphite.

RE: Can lubricant actually damage spring steel?

Greases that use extreme pressure additives do in fact attack steal. It's the chemical reaction with either the oxide layer or the steel surface itself that produces the required lubricating properties.
But for it to happen on the scale required to cause a part to prematurely fail is highly unlikely.

Ron Volmershausen
Brunkerville Engineering
Newcastle Australia
http://www.aussieweb.com.au/email.aspx?id=1194181

RE: Can lubricant actually damage spring steel?

It has nothing to do with the establishment of s galvanic cell. It is important when lubricating springs to be sure the shock absorbers are functioning well. The potential for spring breakage increases once the damping effect of dry leaf upon dry leaf friction is removed. With OEM shocks, lubed springs are great. With no shocks, lubed springs can result in trouble.

Maui

www.EngineeringMetallurgy.com

RE: Can lubricant actually damage spring steel?

Quote (Maui)

It has nothing to do with the establishment of s galvanic cell. It is important when lubricating springs to be sure the shock absorbers are functioning well. The potential for spring breakage increases once the damping effect of dry leaf upon dry leaf friction is removed. With OEM shocks, lubed springs are great. With no shocks, lubed springs can result in trouble.

Fair and correct. But this is a purely physical phenomenon.

The original claim is that "Grease has an adverse reaction to spring steel which causes the steel to degrade and weaken the spring" which appears to have no basis in chemistry.

RE: Can lubricant actually damage spring steel?

Mint, true. The original premise that

Quote:

Grease has an adverse reaction to spring steel which causes the steel to degrade and weaken the spring, so we do not recommend using grease/graphite between the leaves.

is, to the best of my knowledge, patently false. It appears that someone drew an incorrect correlation between SAE 5160 leaf spring failures and the observation that grease was being used to lubricate them. The additional suggestion to

Quote:

Take a look at the front springs on the next large truck you see leaning. There's a good chance the power steering unit will be leaking onto the low side spring.

should make the reader question why the power steering unit would be leaking in the first place. Likely because the truck has significant milage on it. This number of miles creates wear and tear on the shocks, which no longer work as effectively as they should. And for lubed springs, these worn shocks can create the issue.

It appears that the faulty cause and effect line of reasoning for these observations was never actually confirmed, which is why they persist, even if they're are wrong.

Maui

www.EngineeringMetallurgy.com

RE: Can lubricant actually damage spring steel?

It was noted back in the 60s that UFOs were often seen near powerlines. The patently untrue explanation back then was that they absorbed or otherwise enjoyed the electromagnetic energy. Now we know the correct explanation starts with the fact that birds choose to sit singly AND in groups on powerlines (for reasons all their own), and UFOs are simply drawn close by their irresistable LOVE for birds.

RE: Can lubricant actually damage spring steel?

Back when I owned 18 wheelers, I got to have the fun of changing more than a few broken springs, but it never happened to the ones around the engine compartment that always were wet with oil leaks of some type.

rmw

RE: Can lubricant actually damage spring steel?

The lean on the truck would not be due to lube as the lube does not soften the spring, it simply removes a damper. Taking a non gas pressurised damper of a car does not change ride hight. Ride quality sure, but not ride height.

Regards
Pat
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RE: Can lubricant actually damage spring steel?

Hi Maui,

You said "It appears that the faulty cause and effect line of reasoning for these observations .."

My UFO tale was intended to be another "example" of faulty cause and effect reasoning. I figured it would be less controversial than the many examples distributed as news every day.

RE: Can lubricant actually damage spring steel?

On the truck example, one might also think "Hmmm, fluids tend to flow downhill. Maybe that's why the power steering fluid trended toward the lower side...."

Or aliens. [3eyes] Blame the aliens.

RE: Can lubricant actually damage spring steel?

I guess I'm screwed, according to Eaton. I just took my '52 Ford trucks rear springs off for cleaning, lubing, and new bushings. I soaked them in ATF after cleaning all the dirt and scale off. They are original '52 springs (10 leaves on a 1/2 ton, if you can believe that). They have a groove running longitudinally for the express purpose of lubrication.

But my front springs have been replaced with current production Eaton springs, and the left front is right under my leaky manual steering box. 90 wt gear lube passes thru the box like water, keeps the leaves soaking wet. No sag or lean yet, but the front shock is inadequate with no friction to help.

Here's what comes from failure to lubricate on schedule... my rear leaves

RE: Can lubricant actually damage spring steel?

Fretting has worn indented areas into the mating pieces. Fatigue cracks can then start from the fretted areas. One way to mitigate fretting is to LUBRICATE the mating surfaces.

RE: Can lubricant actually damage spring steel?

I also call BS. I see a variety of recommendations from manufacturers and OEMs that would lead to the premature failure of their products as well.

I went to research coil spring failure today and found this article from the british Automobile Association

Coil Spring Failure Season

Their empirical evidence suggests that road salt induced corrosion is the source of spring steel failure, perhaps some materials engineers can confirm or invalidate that claim, but they state:

Hydrogen embrittlement
Electrolytic action between the salt solution, formed by road salting, and the iron in the spring generates free hydrogen atoms which enter the steel and can cause microscopic cracking. Cracks propagate and combine, ultimately leading to failure of the spring.

I would also note that most coil springs are coated, plated, or painted in some way to reduce or eliminate corrosion.

And if I am not mistaken greases are hydrophobic - meaning they would repel salty water from the road and keep it away from the springs.

Conversely if the springs grind against each other with some grit or dirt and grease it may have an abrasive effect like lapping compound.

I believe this recommendation is made with the goal of increasing spring sales but I welcome insights from materials engineers on this report from the AA. I think the question is of a materials nature, and not a mechanical one.

-ATE

RE: Can lubricant actually damage spring steel?

Use cosmoline it has been used for years on all kinds of steels and other metals, any thick protectant like that won't allow dirt in.

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