Is 150 ft-lbs for lugs overkill?

[Carbon Addict]

How does changing wheels and/or lug nuts allow 33% less lug nut torque to provide the same amount of tension in the oem studs that 150 lb-ft provides? Also how does 33% less lug nut torque provide the same amount of clamping force between the wheel and mounting surface on the hub?

Is there a real engineer who could explain this to us simpletons? I am curious about this as well.

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[white15gt]

It doesn't

 

[Stuntman]

What "Industry"?
Who makes these statements?
***For what stud size?

The old standard of smaller M12 wheel studs can be torqued to 100ft-lbs for track use (normal street recommendation is 80ft-lbs), but the stock Ford Mustang M14 (16% larger) wheel stud calls for 150ft-lbs. Same for the Carbon wheels on the GT350R.

+1

Just torque the wheels (OEM, carbon, aftermarket Aluminum) to 150ft.lbs.

 

[Eritas]

Aftermarket wheels, once again I have had this conversation before not looking for arguments everyone is allowed to do as they wish.

I kindly request ask any vendor here and some of the wheel companies on the board what torque rating they use i am certain they if stating honestly and without fear will say 100 ft lbs sir.

150 ft lbs for once again factory wheels and factory studs. for factory we use 150 lbs

I am speaking of aftermarket wheels and lugs

Which "aftermarket wheel" manufacturer recommends 100ft-lbs for the M14 Mustang studs? Please list them.

I know who I'm not buying wheels from.... :doh:

 

[Destro]

https://www.amazon.com/CDI-2503MFRMH-Micrometer-Adjustable-Torque/dp/B002LA1EDO

Peace of mind, 150 ft-lbs. easily achieved

Yup, I have one. 150 ft-lbs x 40 (off/on) = tired arms. I'm old and tired. All my kids wore me out over the years. On top of that it's hot and humid in Florida, so everything takes 5x the effort.
I'll get an adequate impact wrench, and of course use the torque wrench to ensure 150.

This requirement has been thoroughly explained to me in this thread, and I appreciate that. I would be happier if Ford used smaller studs. Not only would it require less torque, but rotational mass would be less as well. Seems like it would have been a worthwhile investment for them in terms of cost basis.

I also own a C7 Corvette Z51. Torque specs on that are a more reasonable 100 ft-lbs. Of course, that car has an aluminum chassis, so more effort was put into it in terms of weight savings. Anyone can go to Australia and have carbon fiber wheels put on their cars. That's easy.

 

[nastang87xx]

I torque my Forgestars to 150 based on their manual for "please refer to your vehicle manufacturer's lug nut torque specifications." or however they worded it.

 

[GTP]

How does changing wheels and/or lug nuts allow 33% less lug nut torque to provide the same amount of tension in the oem studs that 150 lb-ft provides? Also how does 33% less lug nut torque provide the same amount of clamping force between the wheel and mounting surface on the hub?

I was curious about this every since I heard of 100# for the 12mm studs, and now 150# for the 14mm studs on the s550.
14 is 1.35x more cross-sectional area than 12, so going by that ratio would imply 135#.

I think the surface area of the cone part of the lugs may also come into play. Larger the surface area (stock) lugs may need more torque than smaller area (aftermarket) lugs.

So, as PK says, aftermarket wheels with small security lugs may not need as much torque. :shrug:

 

[Offboost]

Is there a real engineer who could explain this to us simpletons? I am curious about this as well.

Simple tightened to specs wheels stay on car!

Not tightened to spec wheels come off car and probably end up hurting someone, plus the damage to your car from riding on the brake rotors and fenders!

 

[GTP]

Yup, I have one. 150 ft-lbs x 40 (off/on) = tired arms. I'm old and tired. All my kids wore me out over the years. On top of that it's hot and humid in Florida, so everything takes 5x the effort.
I'll get an adequate impact wrench, and of course use the torque wrench to ensure 150.

I always use an 18" breaker bar, socket, and special splined socket for my aftermarket, small pattern security lugs. I tighten them by feel, include for track days. I check them after replacing wheels, and after the first session, if not more often. The only time I found that they needed a little more tightening was after I had pulled all four rotors off. This I expected.

So one day I was curious, "How much torque AM I putting on by feel with the 18" bar?" I tightened the lugs as usual, and then dialed up the torque wrench starting with 100#. At 120", the lug turned a little more before I heard the click. So the answer is 120# for my method.

It is important to note that this is the setup I carry in my trunk (I have the spare tire).

I also have a 24" breaker bar, and I'm sure that would take me up to 150#. But then if I put my wheels on with the 24" bar at the house, I would have to stand on the 18" bar should I be at the side of the road with a flat.

 

[krt22]

Is there a real engineer who could explain this to us simpletons? I am curious about this as well.

Long story short, a larger diameter fastener requires more torque to achieve the same clamping force as a smaller diameter fastener. The larger diameter fastener will also have a higher clamping force at its proper torque spec since it can stretch more before yielding.

 

[nastang87xx]

Actually, you are ALL WRONG. Every single one of you...

 

[Epiphany]

The calculated factory torque figure is based on the clamp force and friction needed at the hub/rotor/wheel interface. The stud is designed to stretch a certain amount in order to impart this clamp force. When the lug nuts are loosened, the stud relaxes. In essence, the stud has elasticity or is "elastic."

If you don't stretch the stud properly, you can fatigue the studs (such as if they are under torqued). If you over torque the studs the may yield or become "plastic" meaning they are permanently deformed and are on their way to failure as well.

 

[Paul@PKAUTODESIGN]

Which "aftermarket wheel" manufacturer recommends 100ft-lbs for the M14 Mustang studs? Please list them.

I know who I'm not buying wheels from.... :doh:

I can recommend you other vendors to purchase from sir, that's fine with me, but it seems you may not end up getting wheels from anyone because they normally tell people 100 ft/lbs

once again you do not need to purchase from me im telling you what I have seen done and have done, I have not had a single issue on over 150+ 350/r and over god knows how many other vehicles I have worked on.

Im not here to argue or to point fingers, I have guys that do 150 ft/lbs there's a lot of members that do that.

I run 100 on our shop cars without a single issue, so im speaking from experience.

Please feel free to contact me at 818-408-6989 I would like to just chat so we both understand each other you get my point of word and I get your point of view.

You have to remember manufacturer products require one thing to the other. smaller lugs from what I have been told by the older guys in the business keep in mind 7 years in the industry you learn from older people in the industry as well.

Aftermarket lug nuts do the same OEM torque rating smaller seat compared to the larger OEM lug nuts sir. Just as [MENTION=16078]GTP[/MENTION] stated and [MENTION=16067]krt22[/MENTION]

 

[Paul@PKAUTODESIGN]

If I may

Take a look at the very bottom

https://www.tirerack.com/wheels/tech/techpage.jsp?techid=107&

 

[krt22]

I was curious about this every since I heard of 100# for the 12mm studs, and now 150# for the 14mm studs on the s550.
14 is 1.35x more cross-sectional area than 12, so going by that ratio would imply 135#.

I think the surface area of the cone part of the lugs may also come into play. Larger the surface area (stock) lugs may need more torque than smaller area (aftermarket) lugs.

So, as PK says, aftermarket wheels with small security lugs may not need as much torque. :shrug:

It's not a linear relationship like that, but those numbers are close. The torque specs are typically 75% of the bolts proof load, which scales with diameter.

As for the seating area, that really has a marginal impact on the total torque required to properly stretch a bolt but having the same clamp load with a smaller seating area may make damaging the mating parts (ie the wheel) more possible.

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