THSCC Forums

Chuck Frank wrote:



Chuck, have you had any problems with either dirt, or metal shavings getting stuck in the threads and causing a problem?

So far, I have refused to use anti seize or any kind of oil or grease on the studs or lug nuts. It's partly because I'd have to adjust the torque value by some amount I'm not smart enough to calculate, and partly because I'm concerned about foreign material getting in the threads. After every tire change at an autocross, I will see just a few metal slivers remaining on the lugs. I brush them off with my glove and continue with the process.

That is just one indication I have that it's a good idea to change studs and lug nuts periodically. If I had grease on them, I would be very concerned about the foreign material and those tiny metal slivers building up on the threads and causing a problem.

Somehow.. I guess you've never had that problem or you wouldn't still be doing it. Do you get metal shavings when you change tires? Of course, my torque value is higher than yours, which may be a contributing factor as the stress on the edge of the threads may be a little higher. Factory specs call for 100 ft-lbs on the Vette.

Miles

The Celica is almost 6 years old and has seen a whole crap load of tire changes. I've never broken a stud, never lubricated on and never stripped a lugnut.

I always use a torque wrench for final tightening, but typically use an impact wrench to remove and to pre-tighten.

Scott

I believe any metal shavings I see are aluminum from dragging the wheels across the studs and the nut against the seat. If you read a torque value chart they are with lubricated threads, dry threads would give erronious readings due to uneven/unpredictable galling of the the metal. But again the torque value on lugs is measuring clamping force against the wheel seat not bolt stretch. Dirt isn't a problem because the closed lugnuts doesn't expose the threads to dirt and I try to be careful not to drop them in the dirt when I take them off. You'll see me using a foam pad when I change tires and putting the nuts on it, and I clean them once a year to be sure. I do carry a spray can of brake cleaner and a film can of grease in the trailer just in case I should drop one in sand or dirt. I also can't emphasize enough I use a VERY minimal amount of grease.
OH, and I carry a spare front and rear stud and extra lug nut JUST in case...

_________________
SPIN or WIN!
there's no glory for going slow.

But the clamping force is created by the elasticity of the stud. The stud has been stretched and it is try to contract back to its 'normal' length and this is what creates the tension. The nut and seat are merely an interface for this force.

_________________
Rich
http://www.v8mongrel.com/

Not exactly, in this case the holding force is being created by the slight difference in the angle on the end of the nut vs the angle of the wheel seat creating a wedging action rather than stretching the stud. That's why it's very important to use the proper lug nut that is designed to match the wheels you are using. The wheel manufacturers developed the tapered seat specifically to eliminate the need to stretch the stud to reduce the risk of the stud(s) sudden failure from work hardening fractures and stress induced corrosion.

_________________
SPIN or WIN!
there's no glory for going slow.

Think of the torque equation as T=(mu)*F*r (simplified), mu is the friciton coefficient, F is the preload, and r is the distance from the center of the bolt to the location of the force (your hand).

If you reduce mu (by adding grease), then the required torque value (say 80 ft-lb) is also reduced (to maybe 65). The only problem would be if you use the same specified torque value (80). The reason is that the preload is calculated to be as high as possible to keep the bolt in the elastic range (based on material). Therefore, you may risk of stretching the bolt past its elastic point.

Also, the applied torque is transmitted to a force on the stud. About 80% is used to overcome friction and the other 20% becomes a tensile load on the bolt (thus slightly stretching it). The percentages are estimated.

Class dismissed.


Charlie

Charlie, you are perfectly correct for a standard nut and bolt where the torque of tightening the nut is causing elastic elongation of the bolt. But in a wheel you have a different force at work, i.e. a collet arrangement that develops it's holding force by wedging together two tapers of slightly different angles. It just is convenient to measure that wedging force with a torque wrench. A tapered collet on a drill press or lathe develops it's holding force with practically no torque at all, doesn't even use a method of applying torque to it, the two long shallow tapers are just pushed together. It isn't practical to use a very long shallow tapered collet arrangement like that on a wheel so more pressure is required to wedge the shallow fast taper in a wheel lugnut and seat than just a push of the hand so they use a threaded collet (lugnut) that can be tightened with a wrench to develop enough pressure at the interface to hold the wheel on securely. The reason we limit the torque on our lugnuts is to stop tightening the collet BEFORE elongation of the stud or permanent deformation of the collet taper(s) occurs. Otherwise it would be a lot simpler to manufacture a wheel with plain drilled holes in a flat surface and to use a flat nut and washer to hold the wheel on.
Adding grease to the stud threads is not changing the pressure on the collet taper any appreciable amount, but clean and dry the threads and grease the TAPERED part of the lugnut and seat and the wheel WILL eventually loosen!

_________________
SPIN or WIN!
there's no glory for going slow.

As an aside to clear another misconception brought up in this topic:
Here http://www.centuryperformance.com/torquerec.asp is a torque value chart for various sizes of ARP fasteners, the top quality brand prefered by most racing engine builders.
Note at the top of the chart in green type how the torque is measured:
"Recommended Torque to Achieve Optimum Preload (clamping force) Using ARP Moly Assembly Lubricant or 30-wt oil"
NOT dry.

_________________
SPIN or WIN!
there's no glory for going slow.

Not getting into the theoretical calculation or argument but I have never broken a wheel stud on any car. I did once get crud in the threads on a rear bolt on the Scirocco and had to replace the brake drum as a result. My theory is that I:

--Never EVER let a grease monkey pummel my car with 8000 ft-lb impact wrenches
--Always torque with a torque wrench
--Keep the lugs/studs extremely clean
--Use small amounts of anti-seize

I think anti-seize is the kicker -- the Subaru people continuously seem to break studs and 99% of them seem to not use anti-seize. FYI I use the stock torque figure from the car manual even with anti-seize. There has to be a large safety factor built in to something so imporant so I figure a 20% overtorque is better than any risk of undertorque.

--Kevin H.

_________________
2003 WRX (again!)

I talked to Tom Hoppe this weekend about this issue. He said he was breaking studs all the time a couple years ago (on the WRX). It didn't matter whether he used anti-seize or not. What finally solved the problem was using lugs purchased at Discount Tire Co. The lugs are actually heavier than the stock ones. He also said he uses anti-seize once or twice a year and hasn't broken a stud since switching to the Discount lugs.

Charlie

Yes, since it was so expensive to remove the hub and replace the wheel bearing, I had all 5 studs replaced. Thanks for the heads up on the rears...hopefully I won't have to worry about that for a while!

Charlie

You guys made me do a little more research on the anti-seize question. There is some evidence that both GM and Tire Rack say "do not apply anti-seize to lugs nuts or studs." Dodge seems to feel the same way.

Here's the references:

Tire Rack document, see page 8, in the note after "step 3":
http://www.tirerack.com/images/tr_ownersmanual.pdf


This one is interesting. It is the notes from the "Big Three Brake Symposium 2002" The quote below is from the notes of an individual who attended this seminar, and not any official GM or other mfr publications.
You decide if the source is credible. I wish this was in an official GM publication.

http://www.autotech-training.com/Big%203%20Brakes.pdf
see page 3
"GM says 'No,No, Never use lubricants on nuts, lugs, or between mounting surfaces. Dry and clean only."


For a different perspective, this company makes those wheel guards and says this:

"McGard does not recommend the use of oil, grease or anti-seize lubricants on threads. Spraying the threads with a greaseless lubricant (such as LPS-1) once a year is recommended."

from:
http://www.mcgard.com/custserv/tech_support.asp


Their recommendation of using a "greaseless lubricant" is the only recommendation so far for using any kind of lubricant. I would still go with the car manufacturers recommendations though if the two conflict.

The shop manuual for my 97 Dodge Intrepid (page 22-13) in the section on removal and installation of wheels says "Never use oil or grease on studs or nuts."

Unfortunately, shop manual for the Corvette and the owner's manual give wheel torque values, and do not specify wet or dry, which implies to me that these are unlubricated values. They do not address the issue of lubricants or anti-seize specifically on wheel studs. Since they don't say it's ok to do it, I would infer that it is not. Their torque values do not say "wet" or lubricated, thus I assume those are dry values.

I can find literally dozens and maybe hundreds of posts from people that claim they use anti-seize on their wheel studs, or lug threads, including mechanics and shops. I just can't find any publications from what I consider to be credible technical sources- like a manufacturer of wheels, studs, or a car manufacturer's web site, or a manufactuer's shop manual that actually recommends using anti-seize compound on wheel lug nuts or wheel studs.

If you guys know of such a source, please let me know. I'd be curious to see it.

Miles

Miles, I'm quite confident that what is being discussed in your quotes is lubricant on the mating tapered surfaces of the wheels and lugnuts, not a TINY amount of lubricant on the stud threads. I said above as well that lubricant should NEVER be applied to those surfaces, which is why I'd never use an aerosol spray such as WD40. The OEM manufacturers IMHO are also not addressing "extraordinary" service such as changing wheels a couple times a week. In normal use, a street vehicle's wheels may not be changed more than a couple times total in it's entire lifetime. I can't imagine NASCAR teams not lubricating their wheel studs.
This topic has likely been beat to death now, so I guess the final decision lies with what you are most comfortable with.

_________________
SPIN or WIN!
there's no glory for going slow.

Chuck, I'm not trying to prove one side or the other of this... I'm honestly just trying to learn. I think the safety implications of applying anti-seize and doing it right, if done at all, are worth beating to death if it brings any clarity.

I agree with you that GM would not be thinking about what to say to the typical autocrosser or club racer. Their advice is geared to the general use of their products in normal street driving. Specific applications for racing would likely be different in a variety of subjects...

I wonder if the factory racing divisions of the car mfrs have any official word on this subject....

Interestingly, some car manufacturers (not all) do recommend applying the anti-seize between the rotor and the hub surface to minimize rust and corrosion. So, they are aware that this stuff exists.

My main concern with the application of anti-seize is the proper adjustment of wheel torque to prevent over-stressing the wheel studs.

This manufacturer of an anti-seize compound claims this:

"SAF-T-EZE® Anti-Seize compounds provide maximum bolt tension from minimum wrench torque. In fact, at least 20% less torque is required to get the prescribed tension than to get the prescribed tension than with dry parts."

From:
http://www.saftlok.com/safteze/antiseiz/index.htm

If you don't back off of the "dry" value, I see potential problems.

I see the argument for using anti-seize. Frequent tire changes probably increases potential galling of threads. Does anybody have problems with cold welding between the lug nuts and the wheel surface?

Hmmm.. I wonder how many people are braking wheel studs...

To you guys that are using anti-seize, were you having a particular problem that you were trying to solve? What was it?

FYI,

I don't know the real answer to this question. However . . .

When autocrossing my Datsun 260Z and my Lotus Europa I always used anti-seize. I never damaged a stud in the Z in over 180K of street and autocross use with the oem specified torque. I did use longer oem studs for much of the time I owned the car. I also had no problem with the Europa AFTER I replaced the already stretched studs that were on it when I bought it used.

I was always careful to keep dirt and sand off the studs and lug nuts.

Other results may vary.

Dick

_________________
Dick Rasmussen

FS 50 2018 Mustang GT