When the carpet doesn't match the drapes, how much torque?

[davepl]

If you're using wheels that are not original equipment for your truck, what do you use for torque specs?

I'm using late-model GM 8-bolt wheels; I believe the torque value on the truck they came on was 140 ft/lbs

The shop manual for a '72 says they should be 75 ft/lbs. It doesn't list anything different for 3/4 ton, one ton, 5 bolt, 6 bolt, or 8 bolt. Just says "Tighten wheel nuts to 75 ft lbs"

I'm using brand new Dorman 9/16" studs and new GM tapered lug-nuts.

I would -think- I would use the value for the wheel & nut combination, but how do I know that's not going to bend the hell out of my rotor? Probably OK on an 8-bolt, but doubling the torque value on a 5-bolt can't be good.

Discuss.

[leftybass209]

You have to take in account rotor hub thickness and wheel material. A minimum would be 75 ft lbs. Really i don't remember the last time I've seen a wheel shop torque lug nuts.

[TBONE1964]

I would not worry about bending or distorting your brake rotor. They are plenty thick in the hub area.

What you need to be concerned with as far as over torquing wheel nut is stretch. Every fastener has a torque value and when you exceed that torque value, you are stretching that fastener beyond its limit and that will cause a failure. If you continue to torque a wheel nut past its torque spec, it will eventually break the stud or pull the threads from the wheel stud or the nut.

Here is a chart that shows common torque values depending on fastener size.

http://zerofast.com/torque.htm

Hope this helps.

[kwmech]

I've been torquing down all my 8 lug stuff to 110. 75 seems a bit light to me for a 9/16 stud. The 1/2 ton, 5 lug 1/2'' studs come down to 90 with the steel wheels

[Fitz]

Originally Posted by davepl

If you're using wheels that are not original equipment for your truck, what do you use for torque specs?

I'm using late-model GM 8-bolt wheels; I believe the torque value on the truck they came on was 140 ft/lbs

The shop manual for a '72 says they should be 75 ft/lbs. It doesn't list anything different for 3/4 ton, one ton, 5 bolt, 6 bolt, or 8 bolt. Just says "Tighten wheel nuts to 75 ft lbs"

I'm using brand new Dorman 9/16" studs and new GM tapered lug-nuts.

I would -think- I would use the value for the wheel & nut combination, but how do I know that's not going to bend the hell out of my rotor? Probably OK on an 8-bolt, but doubling the torque value on a 5-bolt can't be good.

Discuss.

I just know this will start an argument BUT I really do not care.

In most cases, the required torque for a fastener holding two mating surfaces has absolutely NOTHING to do with the application. The correct torque is only determined by the grade and diameter of the fastener.

The exception is when those mating surfaces are separated by a gasket (such as a head gasket) then it is the design of the gasket and deformation limits of the gasket that determine the pressure needed to seal the two surfaces independent of the strength of the fastener.

It doesn't take a rocket scientist (but I am one) to figure out that the "Torque to Failure" bolts used by GM on the LS engines for things like the Balancer Pulley, Cylinder Heads and other places are also exceptions to this rule but torque for those fasteners is specified as an initial torque setting and a final torque angle as measured by a torque angle meter.

That's it. End of Story. So, for wheel lugs look up the diameter and thread pitch in Machinery's Handbook and use the torque values specified there; or guess 75 ft Lbs. which is the appropriate value for a 1/2 in Grade 5 fastener.

If you don't have a copy of Machinery's Handbook you can download a PDF here:
http://www.varjepc.com/admin/upload/...20Handbook.pdf

[TBONE1964]

"I just know this will start an argument BUT I really do not care."

It is only my opinion that you can not argue with fact. The other exception to the rule is pre loaded bearing torque but that is a whole different topic.

Good points on your post.

[Kennuck]

Good points Fitz, I agree the Machinery handbook is a great resource. By the way those LS bolts you are referring to are "torque to yield" not "torque to failure"

[Steeveedee]

Be careful what you read and what torque values you use. You may be torquing a metric fastener with the old SAE thread value, or Vice Versa. The thread pitches are different and you may indeed be tightening a fastener "to failure". Use the values you find that are appropriate for the year parts you have.

[davepl]

Ah, but there's the rub. I'm talking about mismatched parts, so which parts? Rotor? Hub? Lugs? Nuts? Wheels?

[Steeveedee]

You need to rely on the information given for the nuts and studs. You aren't going to crush the wheel metal. If you are using metric studs, they tend to run coarser than SAE, that's why the higher torque on the newer fasteners.

[davepl]

Originally Posted by Steeveedee

You need to rely on the information given for the nuts and studs. You aren't going to crush the wheel metal. If you are using metric studs, they tend to run coarser than SAE, that's why the higher torque on the newer fasteners.

Great thinking on the metric thread pitch increasing the torque.

I remember as a teen that I always thought if a shop used an impact to put my wheels on (without a torque stick) that it ran the risk of bending my rotors?

Do you think that's an urban legend, or can it happen?

[Fitz]

Originally Posted by Steeveedee

Be careful what you read and what torque values you use. You may be torquing a metric fastener with the old SAE thread value, or Vice Versa. The thread pitches are different and you may indeed be tightening a fastener "to failure". Use the values you find that are appropriate for the year parts you have.

If your thread pitch gauge doesn't read correctly get one that does. if you don't have one and you just guess about pitch you deserve all of the failures you encounter. Unified National Coarse and Unified National Fine threads have not changed in 90 years so changes to the standards aren't a problem. The international standard for Metric threads ISO 262:1973 was universally adopted in 1973 and has remained un-ammended.

[terry b]

You guys crack me up.

[71swb4x4]

I am posting simply to drop the average IQ in this thread down a few points.

[terry b]

Though i do hate to get my nuts streched.