There is a nylon or some such plastic insert cast right into the alloy wheel hub, so the recommended torque is lower than one might expect. But unless your toque wrench is really accurate, and your bolt threads are dry, the factory spec might be too low. I snug things a bit more than the spec, probably about 85ft lbs, and much beyond that you would risk cracking the nylon.
"But unless your toque wrench is really accurate, and your bolt threads are dry, the factory spec might be too low." I have always found it annoying that most torque specs do not specify whether they are dry or lubricated, and, if lubricated, with what. Oil? Grease? Antisieze? Threadlocker? The difference between dry and lubricated threads exceeds 30%, depending on the lubricant. IOW, if a fastener is supposed be torqued dry to say, 50 ft lbs and it is lubed and torqued to 50 ft lbs, the fastener is being torqued to an equivalent of 65+ ft lbs. Probably doesn't matter much with steel to steel but can be a problem if you are dealing with bolts into aluminum. FWIW...One of the main benefits of using torque wrenches is consistent tightening of fittings...even if the specific torque reading is not super accurate. Many assemblies can be warped and not seal correctly if there is different tensions on the various fasteners and/or improper tightening sequence. Cylinder heads are obvious but wheel lug nuts may not be so obvious - I have routinely run into what seemed to be out-of round brake rotors (pulsating pedal) that was corrected simply by loosening and tightening the lug nuts in correct sequence using a torque wrench to ensure consistent tension.
In general (not Ferrari general, automotive general), the torque spec is whatever is listed. If the threads should have a chemical applied before torquing, then that info is (should be) mentioned in the reassembly docs. The tech isn't expected to determine an adjusted torque value. And you shouldn't put oil or anitiseize on the lugs, btw.
Well, service manuals usually state exactly what to do - torque and lube or dry. But I don't recall seeing anything about that in, for example, any of the Ferrari owners manual instructions covering any work. But maybe I'm misremembering... Torque settings should specifically state that. A typical statement in the many service manuals I have used is typically something like: "Unless otherwise specified, all torque settings are with clean/dry threads." OR ""Unless otherwise specified, all torque settings are with threads lubricated with [whatever]. Some service manuals list a fairly wide variety of lubes as well as dry depending on the fitting. I don't recall that the Ferrari owners manual makes any statement like that re the various torque settings that they mention. I suspect that many people put lubricant of some sort on fittings. Lug nuts are often "anti-siezed"...
For like almost 40 years i have been putting a dab of antisiez on all my lug bolts and wheel studs without any issues, and it holds the torque in spec all the time.
Anyone who Anyone who works on old cars probably puts antiseize on everything, to avoid ever having a broken fastener again! But many studies have been done that say wheel studs and bolts should be installed "dry". I guess keeping the wheel on is more important than eventual service convenience (or road side wheel change). In the real world, a bit of anti seize is fine, and few torque wrenches are so accurate and few fasteners perfectly clean and dry, and that is why I snug mine up a bit tighter. Keep in mind even 90 ft lb does not seem that tight, most people think the impact wrench that can make things so tight you can never remove things is normal.
As long as it does hold the torque spec and as long as it doesn’t get seized and stuck that’s al it counts.
I've changed thousands of tires, torqued to 85 lbs, with no antiseize. Never been an issue. I suppose snow and salt are a reason for it, due to inherent corrosion... but I doubt many Ferrari owners here drive in such conditions.
You mention a bit of anti seize is fine so I assume you use some. You mention that few fasteners are dry and then you mention you are over-tightening your wheel bolts (but you word it differently). Not sure that you actually are aware that lubricated or fasteners that are not "dry," but are supposed to be, require LOWER torque settings. You also comment that few torque wrenches "are so accurate" - hopefully you also realize that not so accurate torque wrenches can read high OR LOW. If it is reading low you are applying even more torque. You write that you "snug yours up" a bit tighter. The word snug sounds innocent and gentle. That's sugar-coating. You're over-tightening. The fact that you haven't had thread/fastener damage or failure doesn't change the over-tightening part.
I recommend clean and dry threads torqued to factory specs. Get you torque wrench tested and calibrated regularly. Always release the tension on your torque wrench when not in use.
"I recommend clean and dry threads torqued to factory specs." Unless, of course, the factory specs are for lubricated threads.
If the factory documentation is silent on the issue of dry vs. lubricated lug bolts, then is dry the default assumption?
One can choose to make that assumption. But with no specific statement by the factory...that's what it is, an assumption. For example, we just bought a used mini cooper and the manual states the torque spec for a lug nut is 103 ft lbs and includes the following: "Attention! Do not apply oil or grease to wheel studs or bolts." Clearly they feel it necessary to specifically state NO lube. Again, there is no industry regulation re this issue...
The factory workshop manual for the 85-89 Porsche 911 Carrera (of which I owned three over the years) gave a torque spec of 130 NM (96 lb-ft), but it too did not state anywhere that torque specs were dry or lubed, or that wheel nuts should be torqued one way or the other. However, the 911 uses aluminum wheel nuts mating to steel studs, and the majority of the Porsche community feels that anti-seize compound should be used to avoid galling and the resulting "stuck lug nuts" due to being torqued dry and not being removed for a long time. But since the Ferrari attachment is steel to steel, I don't really see the need for anti-seize or other lubricant on the threads. I'm therefore going to assume dry. I'll ask my buddy Dave Helms. He knows everything.
Does any car manufacturer ship the car new with anti-seize on the lugs? Not aware of any, but I'm also not aware of everything. Probably because so many over-thinkers pull out the anti-seize... the warning should probably be: "Attention! Do not apply oil or grease to wheel studs or bolts. EVEN IF YOU THINK IT'S A GREAT IDEA, OR READ ON AN INTERNET FORUM THAT IT DOESN'T HURT ANYTHING, IS NEVER A BAD IDEA, OR THAT WE FORGOT TO DO IT AT THE FACTORY WHEN WE MADE THE CAR. WE KNOW ABOUT ANTI-SEIZE. DON'T USE IT ON THIS CAR."
Fair enough comment. I am not likely getting accurate torque readings. I may well be overtightening, or possibly undertightening. So for all the variables, I am really doing this by hand feel. And yes, I know that torque for a lubricated bolt should be about 15 percent less than a new dry fastener. Let me give more detail. I have an old Craftsman click torque wrench, and it has never been recalibrated (and also gets little use, and is untensioned for storage). I don't expect it to be accurate, but it should get me in the ballpark. I cleaned out the lug holes and bolts with brake cleaner. I then use a miniscule amount of a stainless steel based antiseize, threads only, not the bolt head or wheel mating surface, that should definitely be dry. I tighten to the 90lb click, and then go barely like 1/32th of a turn beyond, that's what my "snugging" means. I would describe it as hitting the click point for greater certainty. I also note that based on the size of the wheel bolts, and the steel bolt holes they go into, I expect the fastners could handle way higher torque than the factory spec. It would be the wheel casting with its plastic insert that would be damaged by overtightening. I do carefully inspect these old cast wheels for visible signs of cracking when I have a wheel off, that stress cracking could happen with old alloy wheels regardless of bolt torque issues. I did suggest people leave things dry and torque to factory spec. But in my real world of uncalibrated wrenches, or none being used, and bolts and holes with varying degrees of contamination and corrosion, on a 33 year old car, with inherently fragile alloy wheels, I am sharing what is working for me. Too bad the factory did not use antiseize in the first instance, and adapt the proper torque spec to suit like they do for aircraft wheel torque. Perfect dry bolts and holes are only on factory new parts, even then the factory hub and maybe the bolts probably had a light oil coating from their machining.
I know we (I) have drifted somewhat (OK, a lot) from the simple question the OP asked but I think it's an interesting discussion... I was doing some research and found now that some threaded fitting manufacturers state that lubricants can affect bolt torque/tension (dry/lube) by up to 55% depending on the lubricant! This whole issue is the reason that Torque-To-Yield bolts are becoming more and more common nowadays. The friction that is greatly affected by dry vs lube vs type of lube is not a factor. I remember being extremely annoyed by TTY bolts the first time I ran into them because they are not supposed to be reused. "Seems like a solution for which there is no problem," I thought. But I was wrong. We found that they greatly reduced head gasket issues with cast iron block/aluminum cylinder heads. I always hated AL cylinder heads/cast iron blocks on a performance engine build that was going to be used for 'normal' driving. It was a common "upgrade" but every time a customer specified it I'd suggest they rethink the idea to avoid the very common head gasket issues that resulted. I was usually unsuccessful...AL cylinder heads were bragging rights, you know. Another common 'upgrade' (often another word for "screwup") is installing grade 8 bolts where lower grade bolts were factory installed. Now, the original torque specs are totally incorrect because the correct tension tor the bolt is considerably different. For example, if a grade 5 bolt is properly tensioned at 80 ft lb, installing the same size grade 8 bolt requires the torque to be around 110ft lbs to achieve the proper tension on the bolt. If the original torque spec is used with the grade 8, the fitting could loosen; if the correct torque is used, it could result in warping the mating surface of the components... Back to the original question, but adding in all the discussion...what is the torque for a 3x8 wheel bolt? My answer is, "Heck, I don't know!" I use anti seize and torque them to 70 ft lbs with a torque wrench that I use for only that purpose (lug nuts) and was last calibrated when the factory made it sometime in the '80s!! TBH Lug nut/bolt torque never much concerned me other than the need to tighten in the proper pattern and tighten each fitting to the same "real tight" torque setting. In the old days if you tightened the lug nuts to "as tight as you can" with the crappy wrench provided with the car jack, you were fine, even though that covered a wide range of "torque" depending on the size/strength of the person doing the tightening! Ain't overthinking wonderful?
When I was a teenager and before I learned anything about cars, I used to tighten lug nuts by standing on the end of the lug wrench At least they were torqued consistently...
