Lug Wrench Causality

[abscate]

Old thread alert

With lubrication, you want to torque to about 50-60% of manufacturers spec. The tension of the fastener is governed by thread friction, head friction, and fastener elasticity (aka bolt stretch). Using lube changes the first one a lot, so as a rough SWAG you tighten 1/3 less with lube.

From earlier in this thread...

Its funny, I just had a lengthy debate with my fellow engineer friend on this topic.
My point is the torque we tighten lug bolts should be static state, not dynamic state. Therefore any thing that only reduces dynamic resistance (when you turning the bolt), such as grease or any other forms, will not change the torque at final resting state (after bolt stopped turning).

Do you guys think I won that debate?

I think the poster did win the debate. Unfortunately, the poster was also 100% wrong. The manufacturers torque is a metric to give a designed combination of fastener force (comprised of those three things above) not a Biblical value to be followed. Adding lube changes that balance.

[Clemens]

Oh c'mon, it's only 8 years old

[polskamafia mjl]

It seems like an unnecessary complication to lubricate lug bolt threads. Living in PA with salty winter roads my rims don't rust onto the hubs so there's little risk of the lug bolts corroding. 81ft/lbs isn't very tight and you should have no trouble removing those bolts with a ratchet and cheater pipe. Axle nuts can be removed this way and those are much tighter than these lug bolts.

In fact at work when the impact can't take a lug nut off we do it by hand.

[abscate]

Ah, but when you are on the road and have only the Volvo wrench....lubricated nuts come off easy with out the tool kit.

[mecheng]

I think most OEMS know the bolts will always have some lube on them due to shop conditions/hands. I wouldn't use less than 81ft/lbs / 110NM and yes I use anti-seize, it is a necessity.

[j-dawg]

Ha! I moved from PA to Texas last winter. Got a flat FR tire giving a tour of my work site one Sunday, and I decided to swap the donut spare from front to back so it wouldn't set off the traction control alarm. (Why I didn't just switch the TCS off is beyond me.) I loosened the lugs on the spare, then loosened four of the lugs on the full-size rear tire. The fifth one had me grabbing the roof rail and jumping on the lever until it snapped. That night I needed to drive the friend I was with to Ft Worth, two hours away.

Try finding an open shop with any sort of useful tool in tiny McGregor, TX on a Sunday evening - you're 100% hosed. I had to walk between the gas stations until I found someone kind enough to loan me a tire iron so I could tighten the lugs and drive back to Waco, where just one Pep Boys was open, to buy a new tire and peel out to Dallas immediately. When I got back home I broke the other lugs, which had last been tightened by a shady tire shop in salty Pittsburgh two months before. They took nearly my whole body weight on a three-foot breaker bar.

Now I carry that breaker bar and a 19mm socket in the car at all times. Much easier to use, and hopefully much less likely to snap. Don't trust the factory tire iron!

[kippster41493]

I do like German torque spec "gut und tight" except for things like the engine and transmission where the tolerances are a bit more specific for a reason. I did run into an issue though with a friend that uses the German torque spec. He wanted me to use his car to pick him up from the airport. I noticed there was a MASSIVE amount of front end shake when using the brakes. So much I almost didn't want to use them and just down shift. Well on the way from picking up his car the night before to take to my house one of the tires blew so I went to change the spare, I bent the BMW wrench, broke 2 of my wrenches, (ratchets mistakenly) and ripped a socket. I called him and asked how tight the lug nuts were and he said he did them by hand using the German torque spec. I asked him if he ever wondered why his rotors warped so bad, apparently had no clue.

In short, the German torque spec works on every single vehicle I've ever worked on. Don't be like my friend and go way over board with it, once its hand tight just snug it a little more and you won't have any issues. No anti-seize or other lubricants used when I'm taking off and putting wheels back on.

[cn90]

OK,

I have a little fun reading the Title.

"Lug Wrench Causality" should be...

"Lug Wrench Casualty"

PS: For all vehicle I have at home, I buy dedicated 1/2" breaker bar from Harbor Freight with appropriate socket.
For vehicles that don't have breaker bar, I usually undo the lugs, apply grease, then tighten them using the correct torque.
This way if I have a flat tire in the middle of nowhere, I can use the factory wrench.

[mecheng]

If you don't use anti-seize and your car gets exposed to salt, with time there is a good chance your bolts will seize. I just use a bit of anti-seize; and I rarely re-apply it because it doesn't wash off easily. Never had a nut/bolt seize; ever in my life. My neighbor doesn't use anti-seize and one time his bolt seized; it was a pain to remove and coated in rust. He always uses anti-seize now.

Besides, it lubricates the threads which prevents them from wearing; and when you do service and change to winter tires every year, that is a bonus.
It also makes working on the car easier, bolts can be removed quicker and installed quicker, a good benefit for these cars which needs lots of service.

[kippster41493]

If you don't use anti-seize and your car gets exposed to salt, with time there is a good chance your bolts will seize.

I live in Wisconsin where the roads may as well be made of salt during the winter time, I don't use any anti-seize and don't run into any issues. Even during the winter time when I had to change out a flat I had no issues getting them loose. Not saying it may not help in some cases, just stating my experiences.