This is a response to the "Tire fell off on freeway!!! thread.

"Are you using Anti-sieze on the studs?

If not when you torque them you may not be getting them tight enought since some of the torque would be fighing the rust on the threads.

and be sure the lugnuts are correct shape for the alum rims. "


I have always used the stuff on everything, because it makes it much easier to get things back apart, BUT I was at a seminar awhile back, and was told by a Pap'e Cat, mechanic (this guy REALLY knows his shit) that all torque specifications were on a "dry" figure and if you use anti-sieze or any other lubrication you will over tighten the bolt, he also added that it's common practice that everyone uses the stuff, but you will not get an acurate torque. It made sense to me, the way he explained it. So lets hear some opinions :flipoff2: :beer:

This kinda makes sense, but I would think that the torque is really transfered into pressure against the two mating surfaces.

I know you can torque fine threaded bolts more since the lever force is more because they have more threads/inch and therefore less of a pitch, but I don't really think that the resistance in the threads should count.

Flame me if I'm wrong.

Torque values are always considered " wet values " on clean undamged threads. How are you going to get accurate torque values on for example lug nuts, when one stud may be brand new and oiled and the other stud may be 20 yrs old and rusty. How do you tell if all of your studs/bolts are uniformly rusty?

I'd like to hear some comments on this too :)

here's mine:

for starters, not all torque specifications are for dry clean threads. Head bolts have torque spec's that required moly or anti-sieze. (at least Ford motors that I've had apart do )

I think you are right on the dry torque vs lubed torque and if you torque a lubed bolt to the same spec as what a dry bolt requires you can over tighten it. I think i've seen tables showing max torque by size and grade and it had columns for dry and oiled, but I can't remember where I read this.

and, imo, using antisieze is a lube.

My point on the lost wheel/wheel lug thread, was rusty lug nuts don't get as tight as clean ones, and its a biatch to keep lug nuts rust free. oil tends to cook off but I've found anti-sieze lets you get the lugnuts good and tight and then you can actually get the lugs off again without snapping the wheel stud.

I think torqueing a rustly lugnut means alot of the torque is fighting the rusty threads and not tightening the wheel to the hub as much as is needed. On the removal, it puts a lot of twisting force on the lugnut which weakens it until it eventually snaps.

anyway, I haven't lost any wheels (yet) and I run A/S on my lugnuts, at least when I can find it in the garage... :)

- Dan

i apply anti-sieze to most torqued surfaces as for lug nutsi have never nor do i know the specs for them i just torque them down with a lug wrench. never lost a tire.as for prescion parts such as heads, water pumps i will have to read up if the spec is wet or dry. thanks for the info.:)

The cat guy is correct.

Most torque specs are for clan and dry threads...but not all.

Torqueing to a dry spec with a lubed assembly can have HUGE effects on the tightening, and you WILL overtighten the assembly.

When tightening a threaded assembly what you are really trying to accomplish is a given amount of stretch in the bolt, resulting in a given amount of clamping force to hold the parts together.

Measuring the torque as you tighten is the most common and convenient method of accomplishing this as there is a direct relationship between the torque applied and the stretch/clamp achieved.

However, if you change anything (different bolt material, add lube to assembly, etc. you will not achieve the correct stretch)

In fact, in critical applications, this can be a real problem. that's why in the aircraft industry, and starting to find its way into certain auto applications, in certain critical cases there has been a move to ultrasonically measuring the length of the bolt as it is tightened so that the correct stretch/clamp can be achieved.

A web search will turn up all sorts of stuff on this.

I first noticed the wet vs dry specs when I started using ARP bolts/studs on the engines I was building.

Here is a link to ARPs torque specs with values for what kind of lube your using.

http://www.arp-bolts.com/pages/tech/images/fasttorq.pdf