Lug nut Torq?

[Russell James]

I heard back from my friend that checked into it. 140 lb/ft is correct in Owner's Manual as the "Service spec". They are going to correct the Service Manual which has an error.

The 140 is for the 2010 Camaro - V6 and V8. Other cars that share the same platform/studs/nuts... may have a different service spec number.
I also learned that the service spec is different from the assembly spec, they use a range for dynamic and static and.... I don't really understand all that, but for service it is definately 140 lb/ft.

[redman]

What does your friend base his recommendation on? Was he able to determine the grade of the stud? I looked at a Camaro stud last week at the dealer parts department. There were no grade markings on the head. For a 14mm stud to safely withstand 140ft/lb it would have to be a metric grade 10.9 which is a special heavy duty grade (have never seen a premium grade stud that was unmarked). The lack of a grade marking on the stud leads me to think it's run of the mill steel in which case the max torque should be 100 ft/lb. Your friend may be totallky correct, it would be good to have further details.

[Russell James]

Originally Posted by redman

What does your friend base his recommendation on? Was he able to determine the grade of the stud? I looked at a Camaro stud last week at the dealer parts department. There were no grade markings on the head. For a 14mm stud to safely withstand 140ft/lb it would have to be a metric grade 10.9 which is a special heavy duty grade (have never seen a premium grade stud that was unmarked). The lack of a grade marking on the stud leads me to think it's run of the mill steel in which case the max torque should be 100 ft/lb. Your friend may be totallky correct, it would be good to have further details.

He got a hold of the engineer that spec'd it out. I don't know the data and engineering behind it, but the answer came straight from the source.

There are several cars using that stud size at 140, and a few at 125. I know Corvettes are at 100, but they use a smaller stud. Must be several factors that go into selecting the spec. Supplier for the stud, nut, and wheel, probably go into the mix in determining the number too.

[redman]

Thanks, based upon the emperical data 100 ft/lb still seems correct. There may be several factors that determine torque specs. However thay are always based upon diameter, hardness and coating. In the case of the Camaro lug it's not coated. Not trying to be picky but we all really need to answer this based upon engineering factors and not on.... he said.... or speculation. Overtorqued lugs can present a saftey consideration, warp rotors and snap off in the driving rain while trying to change a flat. Let's keep digging.

[Nine Ball]

I'm still going to use 100 ft-lbs on mine. That is more than enough to hold a wheel on, I'd rather not chance snapping one off at 140 ft-lbs. Even if GM does publish the actual number at 140, I'll still use 100 for my vehicle.

[97one]

Originally Posted by redman

Thanks, based upon the emperical data 100 ft/lb still seems correct. There may be several factors that determine torque specs. However thay are always based upon diameter, hardness and coating. In the case of the Camaro lug it's not coated. Not trying to be picky but we all really need to answer this based upon engineering factors and not on.... he said.... or speculation. Overtorqued lugs can present a saftey consideration, warp rotors and snap off in the driving rain while trying to change a flat. Let's keep digging.

Let's keep digging.....
This has been discussed for over 7 months now.

I & many others said it was 140lbs. over & over again. That is the correct torque.
I stated my reasoning more than once. Read all the prior threads on this.

That does not mean you should use that....Use what you want 80,100 or don't use a torque wrench at all.

[redman]

Ok, Your reasoning has not at all been based upon any mechanical knowledge on your part just what you have read. I used to love racing guys like you. I'm staying at the century mark.

[hypurone]

Originally Posted by 97one

Let's keep digging.....
This has been discussed for over 7 months now.

I & many others said it was 140lbs. over & over again. That is the correct torque.
I stated my reasoning more than once. Read all the prior threads on this.

That does not mean you should use that....Use what you want 80,100 or don't use a torque wrench at all.

I hear what you're saying really. BUT, like I said in a previous post. I checked mine the day I brought it home and they were at 100ft lbs, each and every lug nut. Checked with 2 different torque wrenches (cause I'm anal like that)

[97one]

Originally Posted by hypurone

I hear what you're saying really. BUT, like I said in a previous post. I checked mine the day I brought it home and they were at 100ft lbs, each and every lug nut. Checked with 2 different torque wrenches (cause I'm anal like that)

I am sure that not all bolts & nuts are torqued to the Correct specs.from the factory.

Just one Example.........The rear spoiler nuts were not torqued to (53 in lb ) the correct specs. from the factory.
So, just because it came from the factory that way does not mean that it is correct.


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[hypurone]

Originally Posted by 97one

I am sure that not all bolts & nuts are torqued to the Correct specs.from the factory.

Just one Example.........The rear spoiler nuts were not torqued to (53 in lb ) the correct specs. from the factory.
So, just because it came from the factory that way does not mean that it is correct.


__________________

A very scary and disappointing thought.... that ALL 4 individual robotic fastener devices used to torque the wheels (saw them on ultimate factories Camaro) are incorrect and the computers that control them are wrong or are programmed incorrectly!

In other words, highly doubtful.

[CamaroKen]

Originally Posted by 97one

I am sure that not all bolts & nuts are torqued to the Correct specs.from the factory.

Just one Example.........The rear spoiler nuts were not torqued to (53 in lb ) the correct specs. from the factory.
So, just because it came from the factory that way does not mean that it is correct.


__________________

This is funny, I just started reading this thread and just before I changed pages I told the girl in my office the same thing. Assembly specs are not always the same as the service specs, just like the spoiler nuts were not all tight on all cars. This is a mass produced car, so there will be some bolts or nuts that don't get as tight as they are supposed to.

[ZED SLED]

If it is supposed to be 140 ft/lbs no wonder they don't bother with a spare tire. Could you imagine removing lug nuts tightened to 140 with one of those fold out jack wrenches on the side of the road?

[mtcwby]

Originally Posted by Nine Ball

140 is brutally high. That has to be a misprint!

All my other 14mm lug cars have been 100 ft-lbs. That is what I use.

Here is a good reference, our cars have 14mm x 1.5 studs, it shows 85-90 ft-lbs as typical. Only a 9/16 lug is in that 140 range.

http://www.tirerack.com/wheels/tech/...jsp?techid=107

Last time I looked a 14mm stud is the same size as a 9/16 stud, set them side by side, they are the same, just different thread.
By the way, they are 10.9 hardness studs. Every bolt in the front and rear suspension is 10.9 hardness.

Originally Posted by mclark10

If it is supposed to be 140 ft/lbs no wonder they don't bother with a spare tire. Could you imagine removing lug nuts tightened to 140 with one of those fold out jack wrenches on the side of the road?

140 ft/lbs is not that tight, I use a normal sized 1/2" drive Craftsman ratchet to remove mine after they are torqued to 140.

[redman]

Cool..... how do you know the studs are 10.9? Why the hey would they make a grade 8 equivalent piece and leave it with generic markings?
Not trying to be a pest but I've learned hard lessons by tightening stuff too much. Then someone taught me about bolt grades. Tighter is not always better especially when parts are laying on the tar.