Can lubricant actually damage spring steel? 3

[PackardV8]

From a couple of automotive replacement spring websites,

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

 

[140Airpower]

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?

 

[Compositepro]

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.

 

[mfgenggear]

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

 

[140Airpower]

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.

 

[mfgenggear]

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

 

[swall]

That would be Arco graphite.

 

[gearcutter]

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

 

[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.

Maui

http://www.EngineeringMetallurgy.com

 

[MintJulep]

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.

 

[Maui]

Mint, true. The original premise that

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

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

http://www.EngineeringMetallurgy.com

 

[Tmoose]

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.

 

[rmw]

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

 

[Maui]

TMoose, wtf?

Maui

http://www.EngineeringMetallurgy.com

 

[patprimmer]

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
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[Tmoose]

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.

 

[Maui]

Tmoose, thanks for clarifying.

Maui

http://www.EngineeringMetallurgy.com

 

[TomDOT]

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. Blame the aliens.

 

[RossABQ]

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

 

[swall]

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.

 

[Autotecheng]

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