Anti-sieze and torque

[Eagle]

I've had a long-running dispute with a friend about the correct torque value for lug nuts. Over the years, Jeep factory manuals have changed on this. My MJ FSM (which was printed in 1985, so it came out with the original MJ in 1986) calls for 75 foot-pounds. The 1994 FSM for the Cherokee and Wrangler says 95 foot-pounds, and then says "Never use oil or grease on studs or nuts." My 2000 Cherokee FSM says 85 to 115 foot-pounds.

 

What's a guy to do? The lug nuts haven't changed -- they've always been 1/2x20 with a 60-degree cone on the lug nut.

 

I have had more than one abused XJ or MJ come into my possession with the lug nuts so frozen in place that they were almost impossible to remove. To alleviate that in my life, I have used Never-Seez on my wheel lugs for ... a very long time, like maybe 50 years or so. And I've never had a lug nut either come off, or be frozen in place. But we have to be careful, because PUBLISHED TORQUE VALUES ARE FOR CLEAN, DRY THREADS UNLESS OTHERWISE NOTED.

 

Why is that important?

 

Because when torque values are specified for bolts, the manufacturer doesn't care how hard you have to pull on the wrench. The important thing is the "clamping force." They want the bolt to stretch just slightly, but staying within its elastic limit, so the elastic property of the steel will be trying to remove the stretch. That pulls the nut into firm contact with whatever it's holding, "clamping" the piece between the bolt and the nut. Too little clamping force and the nut may back off. Too much torque ==> too much stretch ==> the bolt may fail because it has exceeded its elastic limit.

 

I've wondered why the torque value for the same lug nut has changed so radically over the years. This is only a guess, but I think it is because alloy wheel are now found on more cars than steel wheels. Aluminum has an unfortunate property: under load, it continues to deform. It's referred to as "creep," and this is why aluminum is no longer used for house wiring. It was, for awhile. And it caused many house fires, because as the wire deformed under the pressure of the screw head, it lost clamping force. The connections became loose, resulting in corrosion, arcing, heat build-up, and fires.

 

My theory, then, is that Jeep increased the torque value for the lug nuts to compensate for the "creep" property of aluminum in alloy wheels.

 

BUT ... all those torques are for "clean, dry threads." The '94 FSM specifically says to not lubricate the threads. Anti-seize is a lubricant. If you use it (and I use it on just about every nut or bolt I touch on my vehicles), the torque values have to be decreased because the lubricant makes it easier to achieve the required amount of stretch (clamping force) with less torque on the nut. If you use the specified torque with lubricated threads, there's a possibility that you may exceed the elastic limits of the bolt, causing it to fail.

 

At the moment, all of my viable XJs and MJs are on alloy rims. I use Never-Seez on the wheel studs. So I've decided to go by the most recent torque spec, which is 85 to 115 foot-pounds. But that's a wide range, and I need to reduce it because of the Never-Seez. The question is: how much do you reduce published torque values when using anti-seize?

 

And sources don't agree. Years ago, my go-to bolt supply emporium had a chart on their web site. It want by actual bolt sizes, and the reductions weren't the same percentage for all sizes. In part, they changed depending on whether the thread pitch is coarse or fine thread. In general, the reduction seemed to average about 15 percent, so that's what I decided to go with. I never like to go to the max on anything (unless there's a compelling reason), so I looked at 110 ft-lbs and 105 ft-lbs. 110-15% = 93.5. 105-15% = 89.25. I settled on using 90 foot-pounds, and I always use a torque wrench to install my lug nuts.

 

This is one of the reasons why I don't allow anyone else to do my wheel rotations. If a tire needs balancing, I remove it and I take it to the shop in the back of my vehicle, loose. The shops may use torque-limiting devices on their impact guns, but if they do they'll be set for dry torque. Not good.

 

Recently, I've found other sources that suggest even greater reductions in torque for lubricated fasteners. This one:

https://www.engineeringtoolbox.com/torque-lubrication-effects-d_1693.html

 

calls for different reduction values depending on what's used as the thread lubricant. They call for reductions of 30% all the way up to 50%. WOW!

 

Another site:

https://www.antiseize.com/PDFs/torque_specifications.pdf

 

This site is specifically about anti-seize. They call for a torque reduction of 25% on fasteners lubricated with anti-seize.

 

What else can go wrong if you over-torque bolts? War story: back in my autocross days, one of the guys in my club had a habit of prepping for each competition by going around his car and giving each lug nut a small turn with a 4-way spanner lug wrench, just to be sure his wheels were tight. No torque wrench -- he made sure the nut moved by about 1/8th of a turn. EVERY SINGLE TIME.

 

By the end of the season, he had pulled the lug nuts right through the wheels. The periodic increase in clamping force resulted in the 60-degree cone of the lug nuts to gradually increase the size of the holes in the wheels. Oops!

 

Bottom line: I recommend using anti-seize on everything. If you use it, be aware that you should reduce the torque values accordingly. Do your own research and decide how much of a reduction factor you think is appropriate. And USE A TORQUE WRENCH. Even the cheap torque wrench from Harbor Fright Tools is better than nothing. I carry one in each vehicle, with a 3/4 x 13/16 reversible impact socket, for tire changes on the road in the event of a flat tire.

 

 

[mjeff87]

Good writeup Eagle.

 

I used to use anti-sieze on wheel studs back when I lived up in PA, due to the winter weather conditions (read: rust), but I've gotten away from it since moving south.  My general rule of thumb on lugnuts has been and still is 90 lb/ft for steel wheels and 100-105 for aluminum/alloy.

 

You wanna really get a serious conversation going about anti-seize and torque values (and not in a good way.....) head on over to Garage Journal and post up that you use it on torqued fasteners.  I think the only more contentious subjects over there is using PVC for shop air lines, LOL.  Or saying that Snap On tools are overpriced pieces of crap.

 

 

 

 

[Eagle]

This is all "old hat" to the guys who have been around cars and engines for awhile. We seem to have some relative rookies coming on board, so I offer this as an aid to getting into doing your own maintenance and repairs.

 

Remember: its worth every penny you paid for it.

 

[gogmorgo]

We never use antiseize on  lug nuts, and never have problems, and we're the guys putting the salt on the roads. Yeah we use impacts on the nuts to loosen them in the shop, but we've never had someone complain they couldn't loosen them if they've had a flat. 200 some vehicles in the fleet, many of them driven by kids with no clue about vehicle care or maintenance. We had plows and sand go out this morning, and likely will on the regular until late May, plus a couple runs a month throughout the summer... that's life in the Canadian Rockies. But salt is an element in this climate. 

 

Torque on the head of the fastener is a pretty poor way of measuring clamping force. As you point out, there are just too many variables. Any contaminants on the threads can increase or decrease friction, sometimes drastically. The friction between the two materials also depends on their exact composition, and isn't even guaranteed to be the same between manufacturers or suppliers. In precision applications where it actually matters, the correct clamping force is determined by measuring how much the bolt stretches.

 

Manufacturers mostly specify a range between the safe minimum where the nut won't back off and a safe maximum that won't cause damage because they know the guy at the tire shop is going to hit them with his torque socket on the rattle gun, but they know he won't have a bunch of them in every single size and torque set, so they give a range to pick one. I suspect the increasing specs are moving upwards to more middle-of-the-road numbers to add an extra factor of safety. That and higher vehicle speeds since the 80's which put more load and vibrations on the wheels. 

 

Now as much as torque specs aren't particularly accurate, there's still a reason manufacturers specify bare and dry threads. Especially as they're moving towards the top of the safe range you could be getting close to damaging things. Current half-tons are specced at up to 150lb-ft, and at that point a 15% increase in clamping load vs fastener torque is pretty significant. The other factor is it's not just clamping force and stretching the lugs to be convened about, conical lug nuts are also exerting outward pressure on the wheel, which stretches the lug holes, can erode the wheel or nut material, and in both cases increases internal stress which reduces the stress the wheel can take from driving, making it more susceptible to damage.

 

But ultimately, I see no need for the antiseize. If you rotate your tires on a regular basis like you're supposed to, you're undoing and doing up your lug nuts on the regular, which breaks free and cleans up corrosion. Clean the threads, torque the nuts back down to spec, re-torque after 25 miles or so, and call it good. We do use antiseize on the wheel mounting surfaces to avoid having to use a sledge hammer to get them off, but like I said, never on the lugs, and it's never been a problem. And don't go thinking our fleet is all newer equipment, generally the light fleet vehicles get surplussed at 200,000 miles or 20 years old. Last winter we surplussed out a '93 f150 with 305,000 miles on it. Old enough it was still reasonable to have a clutch pedal in a light fleet vehicle. We've got some heavy trucks from the 80's as well, still in service with 25,000 hours on the clock. Pulling off lug nuts isn't a problem on any of them. 

[Jeep Driver]

I grease my threads, always have. 

 

I don't use a torque wrench, never will. 

[Dzimm]

I work in plastic injection molding and I continually have issues with people overtightening mold clamp bolts.  We have preset torque wrenches for the proper torque for the bolt size but they have this thought that an extra half a turn past the click will make it tighter.  No matter how many times we tell them to not overtighten the bolts, nearly every bolt we find is overtorqued.  

 

We finally had a mold fall out of a press last week because the threads in the 6" thick steel platen (mold mounting plate), pulled out causing the clamps to fall off.  Luckily the mold was relatively light (~600 lbs) and it fell onto a conveyor belt so nobody was hurt but it's a great lesson to use as a teaching tool for proper bolt torque.  

 

The lesson here is that when using a torque wrench, be sure you are using it properly.  As far as on lug nuts, I've used a torque wrench a few times but usually just snug them up with the 4-way with no sort of antiseize.  I live in Iowa and never have issues with rust on the studs or nuts.  Usually it's the wheel being rusted to the rotor or hub that's the problem.

[Pete M]

7 minutes ago, Dzimm said:

  Usually it's the wheel being rusted to the rotor or hub that's the problem.

 

I put anti-seize in that location too   

[Dzimm]

42 minutes ago, Pete M said:

 

I put anti-seize in that location too   

In the past I've put some around the very edges of the wheel to avoid salt creeping behind the wheel but I'm not sure I like it there.  By putting antiseize behind the wheel, there is no friction between the rotor/hub and the wheel so the only thing holding the wheel on at that point is the nuts.  If the nuts are slightly undertorqued, the studs stretch, or the nuts back off just a thousandth of an inch, you greatly increase the risk of studs snapping because of the wheel slipping and putting a shear stress on the studs.  Bolts can't take very much shear stress.

 

Bolts squeeze/clamp stuff together, the friction between the objects is actually what holds them together.  

[Eagle]

4 hours ago, Pete M said:

 

I put anti-seize in that location too   

 

Me too. (No hash tag!)

[Wounded_Fighter]

I have been using marine based bearing lube as an anti seize near the base of the threads not the entire thread length. Keeps water out so nothing ends up rusty or seized for me. I've not ever used a torque value, but always use 1/6 past sharp rise in torque as a minimum. Haven't lost or had to fight a lug in 10yrs (yet)

 

Not saying it's right, just my method.

/end my 2c.

[cruiser54]

Anti-seize and 85 foot pounds here for years. 

[Me&my86MJ]

I set torque wrench to 105 for alloys rims and 85 to 100 for steel. Never used compounds on threads but do wire brushes them of dirt and debris it they look to need it. Only time I have ever had a problem is using stock steel ford rims on my jeep, they welded themselves to drums in rear and they just never seemed to stay tight.

[Eagle]

It appears that this thread has become mostly about wheel lug nuts, and that wasn't my intention. I used the lug nuts only as an example. The point of my original post was to introduce newbies to the concept of torque reduction when threads are lubricated, and the reason why it's potentially important. It certainly applies to lug nuts, but it's not limited to lug nuts.

 

[88mancheman]

The rule of thumb I learned back in collage was to reduce torque by 25-33% depending on the type of lubricant being used as like eagle stated it’s not the actual torque of the bolt that matters but more of the clamping force the bolt has against the other material, I tend to not wanna use “lubricant” on any threads unless they hold such a small torque value that i worry about them them backing out like the flexplate to torque converter bolts or odd things like that that only bolt 20-30 ftlbs becuase I feel that at Lower spec the bolt won’t reach its elastic point and achieve as much clamping power, just my thought process though

[Eagle]

Small fasteners that you're worried about backing out is what Loctite is made for. Only Blue or Purple, though. Red is high hold and requires heat to remove.

[johnj92131]

On 4/4/2019 at 10:25 AM, Eagle said:

I've had a long-running dispute with a friend about the correct torque value for lug nuts. Over the years, Jeep factory manuals have changed on this. My MJ FSM (which was printed in 1985, so it came out with the original MJ in 1986) calls for 75 foot-pounds. The 1994 FSM for the Cherokee and Wrangler says 95 foot-pounds, and then says "Never use oil or grease on studs or nuts." My 2000 Cherokee FSM says 85 to 115 foot-pounds.

 

What's a guy to do? The lug nuts haven't changed -- they've always been 1/2x20 with a 60-degree cone on the lug nut.

 

I have had more than one abused XJ or MJ come into my possession with the lug nuts so frozen in place that they were almost impossible to remove. To alleviate that in my life, I have used Never-Seez on my wheel lugs for ... a very long time, like maybe 50 years or so. And I've never had a lug nut either come off, or be frozen in place. But we have to be careful, because PUBLISHED TORQUE VALUES ARE FOR CLEAN, DRY THREADS UNLESS OTHERWISE NOTED.

 

Why is that important?

 

Because when torque values are specified for bolts, the manufacturer doesn't care how hard you have to pull on the wrench. The important thing is the "clamping force." They want the bolt to stretch just slightly, but staying within its elastic limit, so the elastic property of the steel will be trying to remove the stretch. That pulls the nut into firm contact with whatever it's holding, "clamping" the piece between the bolt and the nut. Too little clamping force and the nut may back off. Too much torque ==> too much stretch ==> the bolt may fail because it has exceeded its elastic limit.

 

I've wondered why the torque value for the same lug nut has changed so radically over the years. This is only a guess, but I think it is because alloy wheel are now found on more cars than steel wheels. Aluminum has an unfortunate property: under load, it continues to deform. It's referred to as "creep," and this is why aluminum is no longer used for house wiring. It was, for awhile. And it caused many house fires, because as the wire deformed under the pressure of the screw head, it lost clamping force. The connections became loose, resulting in corrosion, arcing, heat build-up, and fires.

 

My theory, then, is that Jeep increased the torque value for the lug nuts to compensate for the "creep" property of aluminum in alloy wheels.

 

BUT ... all those torques are for "clean, dry threads." The '94 FSM specifically says to not lubricate the threads. Anti-seize is a lubricant. If you use it (and I use it on just about every nut or bolt I touch on my vehicles), the torque values have to be decreased because the lubricant makes it easier to achieve the required amount of stretch (clamping force) with less torque on the nut. If you use the specified torque with lubricated threads, there's a possibility that you may exceed the elastic limits of the bolt, causing it to fail.

 

At the moment, all of my viable XJs and MJs are on alloy rims. I use Never-Seez on the wheel studs. So I've decided to go by the most recent torque spec, which is 85 to 115 foot-pounds. But that's a wide range, and I need to reduce it because of the Never-Seez. The question is: how much do you reduce published torque values when using anti-seize?

 

And sources don't agree. Years ago, my go-to bolt supply emporium had a chart on their web site. It want by actual bolt sizes, and the reductions weren't the same percentage for all sizes. In part, they changed depending on whether the thread pitch is coarse or fine thread. In general, the reduction seemed to average about 15 percent, so that's what I decided to go with. I never like to go to the max on anything (unless there's a compelling reason), so I looked at 110 ft-lbs and 105 ft-lbs. 110-15% = 93.5. 105-15% = 89.25. I settled on using 90 foot-pounds, and I always use a torque wrench to install my lug nuts.

 

This is one of the reasons why I don't allow anyone else to do my wheel rotations. If a tire needs balancing, I remove it and I take it to the shop in the back of my vehicle, loose. The shops may use torque-limiting devices on their impact guns, but if they do they'll be set for dry torque. Not good.

 

Recently, I've found other sources that suggest even greater reductions in torque for lubricated fasteners. This one:

https://www.engineeringtoolbox.com/torque-lubrication-effects-d_1693.html

 

calls for different reduction values depending on what's used as the thread lubricant. They call for reductions of 30% all the way up to 50%. WOW!

 

Another site:

https://www.antiseize.com/PDFs/torque_specifications.pdf

 

This site is specifically about anti-seize. They call for a torque reduction of 25% on fasteners lubricated with anti-seize.

 

What else can go wrong if you over-torque bolts? War story: back in my autocross days, one of the guys in my club had a habit of prepping for each competition by going around his car and giving each lug nut a small turn with a 4-way spanner lug wrench, just to be sure his wheels were tight. No torque wrench -- he made sure the nut moved by about 1/8th of a turn. EVERY SINGLE TIME.

 

By the end of the season, he had pulled the lug nuts right through the wheels. The periodic increase in clamping force resulted in the 60-degree cone of the lug nuts to gradually increase the size of the holes in the wheels. Oops!

 

Bottom line: I recommend using anti-seize on everything. If you use it, be aware that you should reduce the torque values accordingly. Do your own research and decide how much of a reduction factor you think is appropriate. And USE A TORQUE WRENCH. Even the cheap torque wrench from Harbor Fright Tools is better than nothing. I carry one in each vehicle, with a 3/4 x 13/16 reversible impact socket, for tire changes on the road in the event of a flat tire.

 

 

Eagle,

Just some comments re aluminum wiring.  My understanding is that the issue with aluminum wiring is related to oxidation rather than clamping force. The fix is conductive grease to prevent corrosion from starting and reltightening the screws holding the wire in place

[Eagle]

7 minutes ago, johnj92131 said:

Eagle,

Just some comments re aluminum wiring.  My understanding is that the issue with aluminum wiring is related to oxidation rather than clamping force. The fix is conductive grease to prevent corrosion from starting and reltightening the screws holding the wire in place

 

The corrosion is a problem only because the aluminum "relaxes" under pressure and allows enough space for the corrosion to take place.

 

I lived for ten years in a house with aluminum wiring. I know too well exactly what the problem is. Plus, as an architect and building inspector, I deal with a lot of electricians.

[johnj92131]

2 minutes ago, Eagle said:

 

The corrosion is a problem only because the aluminum "relaxes" under pressure and allows enough space for the corrosion to take place.

 

I lived for ten years in a house with aluminum wiring. I know too well exactly what the problem is. Plus, as an architect and building inspector, I deal with a lot of electricians.

 

Understand. There has to be a reason why the screws need to be retightened.

[schardein]

My method of applying anti-seize to lug nut studs:  Clean rust/dirt off with wire brush.  Medium coat the threads.  Run lug nut on and off a few times.  Wipe most of the anti-seize off with a shop rag, from both the stud and lug nut.  This usually leaves a little in the bottom of the threads.

 

I always use a torque wrench, and subscribe to Eagle's philosophy of never taking a vehicle to a shop for tire work.  I remove the wheel/tire and take them to the shop, then re-install it myself.

 

I have both Snap-On torque and several Harbor Freight torque wrenches.  I've found the Harbor Freight torque wrenches to be accurate.  Calibrating a torque wrench can be done at home.

 

I've torqued the 1/2" lug studs on my CJ/XJ/MJ to 65 lbsft for decades.  This is clean, very slightly lubed threads.  Not saying this to start a debate, only pointing out I use a spec towards the bottom end of the scale, even considering slightly lubed threads, and haven't lost a wheel yet.

[Minuit]

I'm glad there are people out here that actually give a damn about proper procedure re. tightening fasteners. Thanks for writing this up, Eagle. This is good information that many people are never exposed to. There's not much that I can think of to add, other than to never, EVER forget to retorque fasteners that fasten aluminum parts. The main application of this is aluminum wheels. Forgetting to do this nearly put my truck (and me in it) into a ditch at 55 mph last year.

 

I live in the land of no rust and I garage my '91, so I've never seen fit to lubricate lug nut threads. I also don't put any lubricants on hub faces. As a general rule, I torque my lugs to 100 ft-lb, and critically I check the torque of my lug nuts on a regular basis. Especially with aluminum wheels, lug nuts can back off. Last year, I almost had a wheel come off of my truck and ever since then I've been much more anal about doing these things the right way. Sorry to keep coming back to lug nuts, but I think this is something that everyone needs to hear.

 

If I can possibly avoid it, I also avoid shops. Not only is proper torque almost never a thing, most shops use rattleguns on lug nuts, and that will destroy the two piece factory lugs on our trucks in short order. If possible, I'll remove the tires myself and take them somewhere to be balanced.

 

However, the are a small handful of decent tire shops out there. Tire shops that treat your vehicle with respect and do a good job are worthy of your business. Last year I took my Thunderbird to the Firestone in town to have new tires put on. I didn't expect much, but it was the best option I had at the time. Not only did they use a torque wrench set to 100 ft-lb for my wheels (and yes, I did re-torque them after I got home), they also balanced the tires almost perfectly. I was absolutely blown away by how good of a job they did. I've never had newly balanced tires that didn't vibrate at least a little bit at highway speeds. A year later, that car is still absolutely butter smooth on the highway. I think I'll be taking my tire work to them for the forseeable future.