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edlithgow
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PostSubject: Lubricating/Torquing Wheel Nuts   Mon Oct 13, 2014 10:31 am

Two interelated questions:

Do you lubricate wheel nuts/studs? (I include anti-seize in that term, though that's probably a whole other argument)

Do you use a torque wrench on them?

To declare an interest, my position is Yes and No, but I know many (including, I'm told, many manufacturers) disagree quite strongly.
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Justwatching
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PostSubject: Re: Lubricating/Torquing Wheel Nuts   Mon Oct 13, 2014 8:19 pm

"my position is Yes and No"

Mine is No and Yes :-p

I will now persuade you using the power of logical reasons;

-The value specified by manufacturers assumes the bolt is torqued unlubricated. Applying the same turning force to a lubricated bolt will result in it being tightened down harder than an unlubricated bolt due to reduced shear resistance between the mating surfaces.

-Studs and bolts have an amount of flex allowing them to strech under tension. Too much tension and you risk deforming or even shearing the head and/or threads in the short term, and fatiguing the metal in the longer term. On the other hand, if they're too loose your wheels are coming off.

-You can deform brake discs. Didn't really believe this one until I experienced first hand with my Volvo. Idiots at ShitFit didn't know what the torque was, so they guessed. Brake judder ensued, and sure enough, the discs had excess run-out.

-You don't need lube/copper slip on wheel nuts. They should be coming off once a year minimum, so they're not going to seize on. If the wheels are staying on for periods over a year, you're probably not maintaining the vehicle properly.
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edlithgow
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PostSubject: Re: Lubricating/Torquing Wheel Nuts   Tue Oct 14, 2014 11:18 am

Logical, and, I think, probably the conventional view.

Personally I doubt there's a "right" answer to this. If there is I don't know it, and hadn't really thought about it much until relatively recently, having just used anti-seize and hand-tightened by feel for..er...lets just say a few decades.

Obviously I've bought old cars that have had stuck wheel nuts, from over-tightening or corrosion, but hadn't had that happen subsequently, since I always lubed them.

This changed due to (a) the power of the internet, confusing me with "official" procedures and other information on the (theoretical, at least) downsides of anti-seize (mostly re galvanic corrosion) (b) my own increasing auto-geekiness, and (c) the apparent impossibility of getting Copaslip here, so maybe a couple of years ago I put a wheel on clean, dry and torqued to spec.

Last weekend I had to use a 5 ft lever on a breaker bar to get it off so I could bleed the brakes, so its back to lubing the studs for me, though I may still use a torque wrench if I can figure out what to do with it, even if its only to get an idea what torque my hand-tightening by feel produces.

(You may be right that 2 years is too long and I'm therefore not maintaining the vehicle properly, though I'm not sure why I'd be taking the wheels off every year, unless its to stop them sticking on, which seems a sightly circular argument).

I suspect the (general, but not universal) clean, dry manufacturers recommendation assumes new, perhaps even plated, fastners. On older kit, the relationship between torque and stud tension is apparently quite variable, which may be the reason why truck manufactures apparently often specify oiling the thread.

One work-around is to torque it up dry, but count the turns, then repeat those turns with it lubed. This still requires you to torque a dry thread though, which I don't really like doing, and which I suspect isn't consistent anyway.

Another work-around is to reduce the torque with lubed threads, but recommended reductions I've seen range from 10 to 50%, which sounds a bit arbitary.

Since I can't get anti-seize here, improvisations I've tried or considered include aluminium foil, rubbing with an old tyre weight, graphite pencil, and PTFE thread tape, in combination with cheapo chassis grease or alone.

PTFE tape is my current favorite (no possibility of electrochemical corrosion), but I think it was a mistake to have used it on brake hose threads recently, and I'll have to be very careful to avoid any bits getting into the system when/if I eventually take it apart again.




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Justwatching
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PostSubject: Re: Lubricating/Torquing Wheel Nuts   Tue Oct 14, 2014 1:03 pm

"I'm not sure why I'd be taking the wheels off every year, unless its to stop them sticking on, which seems a sightly circular argument"

Even if you don't need to replace any brake/suspension parts in the span of a year, or change the brake the fluid, it's still advisable to take the brakes apart, clean away the crap build-up and regrease. Most manufacturers recommend at least inspecting the brakes/suspension on an annual basis. I also like to clean the under carriage with a pressure washer once a year or so as a part of corrosion prevention, for which I take the wheels off to get access inside the wheel wells. This is optional of course and not everyone bothers.

"Another work-around is to reduce the torque with lubed threads, but recommended reductions I've seen range from 10 to 50%, which sounds a bit arbitary."

Yeah, I'm also skeptical about that.

"Since I can't get anti-seize here"

I could send you some if you'd cover the cost. No DIY mechanic should be without copper grease.

"I've tried or considered include aluminium foil"

Galvanic reaction?

"rubbing with an old tyre weight, graphite pencil"

Guess it could work. Fiddly and time consuming compared with greasing, not to mention it must be difficult to get it down between the threads.
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edlithgow
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PostSubject: Re: Lubricating/Torquing Wheel Nuts   Wed Oct 15, 2014 4:36 am

From a bit of reading, traditional anti-seize is generally a mixture of one or more metals (copper, aluminium, lead, nickel, the last generally on its own) with graphite and grease. Copper lead and graphite have the potential for galvanic corrosion of steel and aluminium. Aluminium wont corrode steel but is potentially itself corroded in contact with steel or the other metals.

Its argued that this doesn't matter (and given the scale of use of these products, it apparently often doesn't) because (a) the grease carrier excludes water, so there's no electrolyte and galvanic corrosion doesn't happen, and/or (b) the primary function is to prevent metal-to-metal (sliding) contact resulting in adhesion (and galling), and any corrosion products will help to do that by bulking-out the barrier between the metals.

I dunno, but I came across quite a lot of US Dept of Defence bulletins warning of galvanic corrosion caused by these products, particularly graphite, and particularly experienced by the US Navy, which has to deal with expensive aluminium things on aircraft carriers.

I'd be more concerned if I had alloy wheels and I was still in Scotland (which is probably a more hostile environment than a carrier flight deck) but it still puts me off Copaslip a bit.
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Justwatching
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PostSubject: Re: Lubricating/Torquing Wheel Nuts   Fri Oct 17, 2014 2:36 pm

"(a) the grease carrier excludes water, so there's no electrolyte and galvanic corrosion doesn't happen"

Precisely right.

"(b) the primary function is to prevent metal-to-metal (sliding) contact resulting in adhesion (and galling), and any corrosion products will help to do that by bulking-out the barrier between the metals."

Er, right, I think. Not too sure. The copper present in the area between the two surfaces will oxidise and bond itself to either surface, BUT will not bond with itself, thus preventing the two surfaces from joining (IIRC).

"quite a lot of US Dept of Defence bulletins warning of galvanic corrosion caused by these products"

Now this I want to read more about. The use of "caused" makes the statement particularly interesting and runs contrary to the above.

"it still puts me off Copaslip a bit."

I don't see why it should. Apples and oranges, really - the navy's equipment is literally floating in electrolyte. I suspect the anti-seize simply failed to completely prevent a galvanic reaction in such a harsh environment, rather than "caused" one itself.
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edlithgow
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PostSubject: Re: Lubricating/Torquing Wheel Nuts   Fri Oct 24, 2014 5:09 pm

Justwatching wrote:
"(a) the grease carrier excludes water, so there's no electrolyte and galvanic corrosion doesn't happen"

Precisely right.


Well, it'll be precisely right some of the time, but in hostile conditions (where heat melts the grease, for example) it might not be.

Justwatching wrote:
"

"(b) the primary function is to prevent metal-to-metal (sliding) contact resulting in adhesion (and galling), and any corrosion products will help to do that by bulking-out the barrier between the metals."

Er, right, I think. Not too sure. The copper present in the area between the two surfaces will oxidise and bond itself to either surface, BUT will not bond with itself, thus preventing the two surfaces from joining (IIRC).


I think that's incorrect in the case of copper, which is more "noble" so won't corrode if coupled with steel or aluminium, which will themselves be corroded. I've read accounts of aluminium yachts being holed by loose change dropped into the bilges.

Justwatching wrote:
"

"quite a lot of US Dept of Defence bulletins warning of galvanic corrosion caused by these products"

Now this I want to read more about. The use of "caused" makes the statement particularly interesting and runs contrary to the above.

Can't find it, I'm afraid. It was in replies in quite a long thread on an AR-15(gun) forum. Thought that'd be easy to find again but there's a whole raft of them (American's y'know?), and one can only take so much redneck.

Justwatching wrote:
 

"it still puts me off Copaslip a bit."

I don't see why it should. Apples and oranges, really - the navy's equipment is literally floating in electrolyte. I suspect the anti-seize simply failed to completely prevent a galvanic reaction in such a harsh environment, rather than "caused" one itself.  

Planes on carriers aren't actually floating in electrolyte directly unless somethings gone badly wrong. Though they are probably more fragile than an alloy wheel on a Scottish winter road, they probably don't get much more exposure to salt spray.

They also make aluslip (which electrochemically should be a better choice) and zinc based compounds, which should be better still, or you can avoid electrochemical effects altogether by using a PTFE-based paste, but I can only get the thread tape here.

I've seen reference somewhere to Milk of Magnesia (Magnesium Hydroxide, I think) as a high temp anti-seize used on B52 engines. I might be able to get that here.
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edlithgow
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PostSubject: Re: Lubricating/Torquing Wheel Nuts   Tue Feb 17, 2015 3:20 am

For what its worth, break out torque when recently removing a wheel from my PTFE/greased wheel studs (hand-tightened) was consistent at about 35 ft-lbs.

I of course don't know what the bolt tension was.

I made "aluslip" in-situ, by abrading the shoe supports on the backplate with TV aerial in a power drill chuck, having applied a trace of bearing grease.

I can make small quantities by hand, by rubbing the dimple in the bottom of a coke/beer can (used like a pestle) with some aluminium foil. A cut can top also be used as a clean-up tool, chasing threads and leaving some metal behind.

Its more hassle than just buying product, but I don't usually need much, so not too bad.
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