Correct Lug Nut Torque

[ron69912t]

What is the correct tightning Foot Pounds for aluminum lug nuts??

Thanks,
Ron D

[Morrie]

heh heh heh I bet the answer would come faster on the 911 board Ron!

I am curious too, as I just got 2 sets of Fuchs, one for my 912 and 1 for Cindy's.

Also, I have no lug nuts. Is this something I can get from the local auto parts store? Anyone know the specs?

Morrie

[ron69912t]

Morrie:
I see a lot of lug nut sets on e-bay, mostly steel.

I am cautious about over tightning an aluminum lug nut because I broke one off (sheared off) trying to loosen it two years ago it was so tight. It was a bear to grind out so I could get the wheel off. Now I use anti-sieze on the aluminum lug nuts.

Thanks,
Ron D

[Morrie]

I plan to use a torque wrench for sure Ron. What are the pros and cons of AL vs steel lugs? I am clueless on this....

[ron69912t]

Morrie:
My guess is that the aluminum was used because they are lighter in weight than the steel lug nuts. You know every ounce of weight counts in Porsche's mind.

I had some contact with McLean Fogg Lock Nut Co years ago, they made lug nuts for most of the Detroit car makers. Their engineers had a lab that tested all kinds of lug nut materials and I remember one of their main concerns was creep or cold flow of the lug nut material so it did not loosen up after a long time.

I would think aluminum creeps or cold flows more than steel so in that regard steel would keep tight longer. All stressed metals creep to some degree.

I'll stick to my Aluminum lug nuts and just check them more often.

Thanks,
Ron D

[Duke]

The correct torque is 94.

[ron69912t]

Duke:
Thanks. Do you know if it the same for aluminum & steel lug nuts ie 94 Ft Lbs.?

Ron D

[WFBowen]

Ron:
Interesting info on lug "creep." Those of us who have put cars on the track can attest to fact that the lug nuts (either type) are constantly working loose. Most clubs now require steel lug nuts for track use - why, i'm not sure, as when these cars were raced in SCCA years ago, they were usually on alloy nuts. Maybe the alloy threads are more subject to damage, etc.

Morrie:
If you're looking for lug nuts, be very careful. The size and pitch are not uncommon, but the mounting shoulder must be round, not conical as most lugnuts are. The only one I've found that is a dead-on fit is the Volkswagen bus (later style with disc brakes). If you have a "pick-a-part" in your area check the VW busses out-you'll see the ones that fit. For those who've been to pick-a-part, note that when checking out and showing your items to the cashier: If you state that they're wheel nuts, you'll pay $.50 each, or $10.00 a set. If you state that they're just " body or chassis nuts", it's $3.85 for everything! Sure beats the $50 Ebay sets.

Bill

[ron69912t]

I did a search on this BB for lug nut torque and found a chart showing a 12mm bolt (19mm wrench size) has a recommended assembly ft-lbs of 95 and aluminum has 40 ft-lbs both with lubricated threads. It seems logical that aluminum would be less than steel.

FYI

Ron D

[Duke]

My Fuchs wheels have always been torqued to 94. I think 40 would be inviting disaster.

[Sweetheart912]

I agree with Duke about inviting disaster.

All bolts or studs are designed to stretch a miniscule amount when optimal clamping load is achieved. This elasticity of the stud or bolt is what helps to secure the wheel on the hub. When torqued to specification, this is referred to as achieving the proper "clamping load."

I have used steel lugs both on alloy wheels & steel wheels, and alloy lugs on alloy wheels. I have always torqued 95 ft lbs on both types of lug nuts & not had a problem. Porsche spec is 95 - the same for a 356, 911/12, my 944, a 996 etc. Go ahead-check it out. Porsche doesnt differentiate this spec between alloy or steel lug or by wheel type. Even the fragile magnesium gas burners @ 71 vintage are 95 ft lbs with alloy lugs.

What Bill pointed out is just as important; that the correct shape on the bottom of the lug nut is used. Porsche uses radius seats, vs flat vs conical types. Radius seats also are called "ball" or "rounded" seats. As the name implies, the seat features a radiused "ball" shape that nestles into a ball-shaped pocket in the wheel.

Steel lugs for racing applications, to my understanding, are primarily because of similarity of expansion rates of the steel lug & the steel stud during extreme racing heat cycles. Less chance of variation to affect the clamping load. I raced my E production Speedster on & off for over 2 decades & they would never pass my car at tech with alloy lugs (oops-busted). The reason given in the SCCA GCR & by the tech man, from the mid-70's on, was always dissimilar expansion/contraction rates-safety. Practically speaking though, steel lugs are much much easier to work with track side.

(This para was added since the few pm's requesting experience with alloy lugs) Alloy lugs are very durable. High grade high tensile aluminum. IMHO more for show than for go. Anytime I bought a used set, I'd check them out with a magnifying glass before installation. Some had cracks that you wouldnt see with the eyeball....straight to the garbage. The cracks were usually at the base & around the circumference. Undoubtedly from someone using an uncontrolled impact gun, or "bending down" on the lug wrench instead of keeping it straight during tightening, or some other evil humor. Make no mistake, they are very tough and strong but "sensitive" to cross threading and ham handed installers with impact guns or breaker bars. Like me, the older aluminum lugs are getting brittle with age, so I'd suggest checking yours with a glass next time you have them off, you may have one cracked & ready to break anytime.

I always use Never-seize on any lug, but especially on alloys. If you have one stuck, try a little heat on the alloy lug first before you try to muscle it off.
Cheers.

[Hoffman912]

i always did mine at 93. never had a problem. always recheck at tune up (3k). if i had to take my tires off.. i check after te 1st 100 miles.

[Zeke]

Steel lug nuts are spec'd for track events, in part, because alloy nuts hide the threads. Drivers who use spacers can run out of threads (min 11 full turns) w/o longer studs and the inspector can't see that. If one were to cut off the head of an alloy nut for the purpose of determining how many threads are captured, he may as well use an open steel nut. IOW, what's the point?

And, if longer studs are installed, there is a risk of bottoming out the alloy nut thinking it's torqued to spec. Again, open nuts are better.

Alloy nuts are for stock wheels on stock studs w/o spacers. Too much monkey business at the track to rely on that.

[Morrie]

Sounds like at least short term I can use the steel open end lugs from my original steel wheels on the Fuchs with no mechanical issues.... is that correct?

[Sweetheart912]

Morrie, that is correct. If you haven't tried it, there is a product found at most hardware stores call Trustan. It is a rust preventing product. It is a very thin consitency, like water, & you brush it on the exterior of the steel lugs and the top 2 or so threads of the stud. I use one of those small model car brushes for this. Dries to a nice black anodized finish & is identical color as on the paint used on the alloys. Don't forget the never-seize on the studs. Cheers.