Wheel lug nuts

[CaptDave]

What’s the torque spec on them again? I’m on the road and don’t have anything car related with me. Thanks!

Sponsored

 

[kilobravo]

150, Dave.

 

[Snoopy49]

Don't leave home without it.

2020-Ford-Mustang-Owners-Manual-version-1_om_EN-US_07_2019.pdf

2020-Ford-Mustang-Shelby-GT500-Supplement-version-1_su_EN-US_08_2019.pdf

 

[Tomster]

150, Dave.

Do they still have the +/- 15 ft/lbs attached to that spec? I have always thought 150 is too much. On my Rs (even on the track) I use 135 ft/lb. That's just my preference that has worked for me.

On a side note, if anyone uses titanium lugs, a thread lube needs to be used for dissimilar metals and the above torque values are out the window.

 

[kilobravo]

Do they still have the +/- 15 ft/lbs attached to that spec?

Yes, they do, Tom and no difference indicated for alloy or CF.

And thanks for the lube tip on the Ti lugs as well as the heads up on what the torque should be.

I'm hoping that Terrance has a pretty good idea as to what it should be when using them. <fingers crossed>

 

[Tomster]

Yes, they do, Tom and no difference indicated for alloy or CF.

And thanks for the lube tip on the Ti lugs as well as the heads up on what the torque should be.

I'm hoping that Terrance has a pretty good idea as to what it should be when using them. <fingers crossed>

I've gone round and round with Terance about this issue. To achieve the same preload on the studs while using any kind of thread lube, it would require an engineer to test using a specific thread lubricant. I use ARP and use an approximated torque reduction value. It is only an estimation and for that reason, I dont use the titanium lugs for the track. I was hoping he would have had or will get the engineering done, but it would be an extra expense to an item that is already very expensive. He does small batches and to him it's probably not cost effective.

 

[kilobravo]

Roger, Tom and thanks.

 

[CaptDave]

Thanks KB and Earl, I appreciate it.

 

[Dunk812]

Lubricant Torque Reduction (%)
No lube 0
Graphite 50 - 55
White Grease 35 - 45
SAE 30 oil 35 - 45
SAE 40 oil 30 - 40

Standard torque reduction for lubricated bolts. We almost always use graphite or white grease. I would not use oil and with a plus minus 15 ft pounds I would use the lower % and torque to plus zero and minus 10. Just an old ass ME opinion.

 

[Tomster]

Lubricant Torque Reduction (%)
No lube 0
Graphite 50 - 55
White Grease 35 - 45
SAE 30 oil 35 - 45
SAE 40 oil 30 - 40

Standard torque reduction for lubricated bolts. We almost always use graphite or white grease. I would not use oil and with a plus minus 15 ft pounds I would use the lower % and torque to plus zero and minus 10. Just an old ass ME opinion.

Those are approximations. Keep in mind the reason a specific torque is eatablishes is to obtain the engineered preload on the studs. The only way to do it right is to have the engineered data for a specific line and lug.

 

[Dunk812]

Those are approximations. Keep in mind the reason a specific torque is eatablishes is to obtain the engineered preload on the studs. The only way to do it right is to have the engineered data for a specific line and lug.

I agree that to get the exact number I would need much more information and would need several nuts and studs to test to failure. I would say that using the data supplied from the engineering tool box and handbook would be safe as it has margin built in it reducing the risk to a green in the risk cube probably a 2 on likelihood and a 3 on impact because having more then 1 stud fail is pretty unlikely. I myself am pretty risk adverse so I would not use the titanium lugs at all.

 

[Tomster]

I agree that to get the exact number I would need much more information and would need several nuts and studs to test to failure. I would say that using the data supplied from the engineering tool box and handbook would be safe as it has margin built in it reducing the risk to a green in the risk cube probably a 2 on likelihood and a 3 on impact because having more then 1 stud fail is pretty unlikely. I myself am pretty risk adverse so I would not use the titanium lugs at all.

And that's the problem, no lube manufacturer I contacted would supply torque reduction values. ARP flat out declined unless it was used with their products. The lawyers are to blame I guess.

Tob is our resident torque expert. He specified the lengths that one would have to go to obtain the proper engineering spec. I went so far as to count the turns on a dry lug and compared it to a wet lug. The experiment did not go well. I had to knock it off because the lubricated lug torque value went way higher than it should have to reach the equal dry torque lug turns.

So I just settled on an approximate value of 120 ft/lbs with ARP

 

[Epiphany]

Tom, one way to do this if using stock Ford GT500 wheel studs would be to measure the amount of stretch (of the wheel stud). If you were to use a clean and dry stud/nut, you could measure the amount of stretch when using factory torque figures (assuming the wrench is calibrated). You could try achieving the same amount of stretch with ARP lubricant (for example) on it by measuring stud elongation. This would correlate to a ~torque figure but until you saw some consistency I'd do this a few times.

It'd also be nice to measure clamp force at the factory torque figures when dry. Clamp force can vary by quite a bit doing it differently in terms of dry/lubricated.

This video gives you an idea of how much clamping force can vary depending on the state of the fastener, dry or lubricated (never use anti-seize!). What you don't see in it though is stretch and you really want to know if the fastener has yielded. That's why measuring stretch is really the best way to do this.

 

[Tomster]

Tom, one way to do this if using stock Ford GT500 wheel studs would be to measure the amount of stretch (of the wheel stud). If you were to use a clean and dry stud/nut, you could measure the amount of stretch when using factory torque figures (assuming the wrench is calibrated). You could try achieving the same amount of stretch with ARP lubricant (for example) on it by measuring stud elongation. This would correlate to a ~torque figure but until you saw some consistency I'd do this a few times.

It'd also be nice to measure clamp force at the factory torque figures when dry. Clamp force can vary by quite a bit doing it differently in terms of dry/lubricated.

This video gives you an idea of how much clamping force can vary depending on the state of the fastener, dry or lubricated (never use anti-seize!). What you don't see in it though is stretch and you really want to know if the fastener has yielded. That's why measuring stretch is really the best way to do this.

Yea yea. we went down that road, remember? You cited the same references.

I counted turns on the dry lug to correct preload. Then came the lubricated lugs. I was uncomfortable honking down on them any more than I did before calling it off.

I still await engineering data from T

 

[Epiphany]

We have indeed touched on this before. I may be getting old quickly but I haven't forgotten it yet.

I've never been a fan of turn counting and that's why I suggest measuring stretch. ARP favors stretch as the best measure too. This is exactly what I would do Tom.

- Weld the appropriate nut size socket to an adapter (crow's foot, etc) that you could fit on the end of a known accurate torque wrench. Calculate the correction factor for using the adapter length you are using.
- Install a wheel in place 4 out of 5 nuts torqued as you normally would with a wrench.
- Thread the remaining nut on its corresponding stud by hand to where it just makes contact with its seat on the wheel.
- Slip the socket into place over the nut in the wheel and attach the torque wrench.
- Set up a dial indicator that would go through the socket and touch the end of the stud. Zero it out.
- Torque to a corrected 150 (I'd also do 135 and 165 just for data points) and measure the amount of stretch. I'd try this a few times on different studs for backup.
- Start over again, this time lubricate with ARP thread lubricant.
- Pay attention to the torque value as you tighten, matching the dry stretch value.

This would allow you to impart the same amount of preload on the factory wheel studs, albeit at a different torque figure due to the added lubrication. Assuming everything else remains constant (same lube, applied in the same amount at the same location, etc) you should now have a figure to use with your torque wrench.

Sponsored