Dry or oil on lug nuts
07-29-2005, 02:07 PM
#3
Drifting
Originally Posted by Quacker
What torque spec do you use when using oil on the lug nuts
07-29-2005, 04:05 PM
#4
Drifting
I have always used the engineering manual on material specs. They always give torque for clean/lubed fasteners. A better way to tighten is to measure % of streatch on the bolt,, but we don't really do that on wheels. So I torque to 95#'s in the correct pattern in 20# increments, to 80 #'s then 10 #'s and finally 5 # to finish, with a "film of grease" on the lugs. Read the film to be only enough to make a shiny film,,not glob. Never had a problem with Clean/Lubed/torqued fasteners,, even the wheels on my 64, 87 and C5. 99 Nassau Blue
07-29-2005, 06:50 PM
#5
Team Owner
Quote from GM Service Manual for 2002 Corvette, page 3-97:
"Notice: A torque wrench or J39544 must be used to ensure that wheel nuts are tighened to specification. Never use lubricants or penetrating fludis on wheel stud, nuts, or mounting surfaces, as this can raise the actual torque on the nut without a correspondine torque reading on the torque wrench. Wheel nuts, studs, and mounting surfaces must be clean and dry. Failure to follow these instructions could result in wheel, nut, and/or stud damage."
"Notice: A torque wrench or J39544 must be used to ensure that wheel nuts are tighened to specification. Never use lubricants or penetrating fludis on wheel stud, nuts, or mounting surfaces, as this can raise the actual torque on the nut without a correspondine torque reading on the torque wrench. Wheel nuts, studs, and mounting surfaces must be clean and dry. Failure to follow these instructions could result in wheel, nut, and/or stud damage."
07-29-2005, 09:57 PM
#7
Burning Brakes
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Originally Posted by Oldvetter
NEVER use oil on lug nuts. Use a wire brush to clean if necessary. A friend of mine used oil, ended up having car flat beded when wheels came loose!
Ron ...
07-29-2005, 10:33 PM
#9
Melting Slicks
Everybody has a different way and they all seem to work. I torque mine to 80 lbs. and have not lost a wheel in 5 yrs.
07-29-2005, 10:44 PM
#10
Originally Posted by RonJ
That's odd, I've used a "Never Seize" compound on the wheels nuts of all my vehicles for years and have never had a problem.
Ron ...
Ron ...
07-30-2005, 06:15 AM
#11
Originally Posted by Sandra Bigwoode
If you have ever had the wheels removed and replaced to change tires with the tire monkey using an old and loose impact wrench, you have probably had the studs over-torqued.
Next tire change, use a wire brush on the studs, smear some anti-seize compound on the studs and have the tire monkey use a 100'# torque stick on the old impact wrench.
Next tire change, use a wire brush on the studs, smear some anti-seize compound on the studs and have the tire monkey use a 100'# torque stick on the old impact wrench.
07-30-2005, 09:35 AM
#12
Pro
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Hey Guys,
Hit this link to the ARP site – Look at this chart and you’ll see how much lubing a thread changes the recommended torque required to achieve it’s full clamping force. In short – lubing the thread isn’t so much a sin “IF” your tightening / stretching to spec
www.arp-bolts.com/pages/tech/images/fasttorq.pdf
A lubed Vette wheel stud is being stretched past it’s engineered limit at 100FtLbs.
Under torqueing is a danger too – under torqued fasteners never making full stretch / load can get Cycled – Scary thought when you have race tires on that develop big forces on the studs at every turn.
Read Carroll Smith's, Nuts, Bolts and Fasteners and Plumbing Handbook – This book is Super!
Hit this link to the ARP site – Look at this chart and you’ll see how much lubing a thread changes the recommended torque required to achieve it’s full clamping force. In short – lubing the thread isn’t so much a sin “IF” your tightening / stretching to spec
www.arp-bolts.com/pages/tech/images/fasttorq.pdf
A lubed Vette wheel stud is being stretched past it’s engineered limit at 100FtLbs.
Under torqueing is a danger too – under torqued fasteners never making full stretch / load can get Cycled – Scary thought when you have race tires on that develop big forces on the studs at every turn.
Read Carroll Smith's, Nuts, Bolts and Fasteners and Plumbing Handbook – This book is Super!
07-30-2005, 09:07 PM
#15
Race Director
If you lube, then you MUST reduce the torque by a "K" factor. Don't know what a "K" factor is? Then do NOT lube the threads prior to applying the specified torque. Doing so will create an overtorque condition.
08-01-2005, 11:34 PM
#18
Burning Brakes
Yall worry to damn much. I just torque them on at the recommended value and don't care. None of this torque in increments crap. Been doing that for I can't tell you how many years and I've never had a tire fall off no matter how hard I beat it.
Last edited by BigBlue; 08-01-2005 at 11:36 PM.
08-02-2005, 12:02 AM
#19
Race Director
K Factor is a torque coefficient between bolt and receptacle. It is a function of the materials' frictional characteristics, which are based on surface finish, coatings and so on.
Typical Steel Bolt 0.20
Zinc-Plated 0.20
Lubricated 0.18
Cadmium-Plated 0.16
Nonplated Black Finish 0.30
Question: How is bolt installation preload calculated?
Answer: Bolt pretension, also called preload or prestress, comes from the installation torque T you apply when you install the bolt. The inclined plane of the bolt thread helix converts torque to bolt pretension. Bolt preload is computed as follows.
Pi = T/(K D) (Eq. 1)
where Pi = bolt preload (called Fi in Shigley).
T = bolt installation torque.
K = torque coefficient.
D = bolt nominal shank diameter (i.e., bolt nominal size).
Torque coefficient K is a function of thread geometry, thread coefficient of friction t, and collar coefficient of friction c. Look up K for your specific thread interface and collar (bolt head or nut annulus) interface materials, surface condition, and lubricant (if any). ("Torque specs for screws," Shigley, and various other sources discuss various K value estimates.) If you cannot find or obtain K from credible references or sources for your specific interfaces, then you would need to research to try to find the coefficients of friction for your specific interfaces, then calculate K yourself using one of the following two formulas listed below (Shigley, Mechanical Engineering Design, 5 ed., McGraw-Hill, 1989, p. 346, Eq. 8-19, and MIL-HDBK-60, 1990, Sect. 100.5.1, p. 26, Eq. 100.5.1, respectively), the latter being far simpler.
K = {[(0.5 dp)(tan + t sec )/(1 – t tan sec )] + [0.625 c D]}/D (Eq. 2)
K = {[0.5 p/] + [0.5 t (D – 0.75 p sin )/sin ] + [0.625 c D]}/D (Eq. 3)
where D = bolt nominal shank diameter.
p = thread pitch (bolt longitudinal distance per thread).
= thread profile angle = 60° (for M, MJ, UN, UNR, and UNJ thread profiles).
= thread profile half angle = 60°/2 = 30°.
tan = thread helix angle tan = p/( dp).
dp = bolt pitch diameter.
t = thread coefficient of friction.
c = collar coefficient of friction.
D and p can be obtained from bolt tables such as Standard Metric and USA Bolt Shank Dimensions.
The three terms in Eq. 3 are axial load component (coefficient) of torque resistance due to (1) thread helix inclined plane normal force, (2) thread helix inclined plane tangential (thread friction) force, and (3) bolt head or nut washer face friction force, respectively.
However, whether you look up K in references or calculate it yourself, the engineer must understand that using theoretical equations and typical values for K and coefficients of friction merely gives a preload estimate. Coefficient of friction data in published tables vary widely, are often tenuous, and are often not specific to your specific interface combinations and lubricants. Such things as unacknowledged surface condition variations and ignored dirt in the internal thread can skew the results and produce a false indication of preload.
The engineer and technician must understand that published K values apply to perfectly clean interfaces and lubricants (if any). If, for example, the threads of a steel, zinc-plated, K = 0.22, "dry" installation fastener were not clean, this might cause K to increase to a value of 0.32 or even higher. One should also note that published K values are intended to be used when applying the torque to the nut. The K values will change in relation to fastener length and assembly running torque if the torque is being read from the bolt head.
One should measure the nut or assembly "running" torque with an accurate, small-scale torque wrench. ("Running" torque, also called prevailing torque, is defined as the torque when all threads are fully engaged, fastener is in motion, and washer face has not yet made contact.) The only torque that generates bolt preload is the torque you apply above running torque.
A few more things to be aware of are as follows. Bolt proof strength Sp is the maximum tensile stress the bolt material can withstand without encountering permanent deformation. Published bolt yield strengths are determined at room temperature. Heat will lower the yield strength (and proof strength) of a fastener. Especially in critical situations, you should never reuse a fastener unless you are certain the fastener has never been yielded.
1.1 Bolt Preload Measurement
If a more accurate answer for bolt preload is needed than discussed above, the specific combination and lubricant would have to be measured instead of calculated. Measurement methods are generally involved, time-consuming, and expensive, and are beyond the scope of this article. But perhaps one of the simplest and least expensive methods, to test specific combinations and lubricants, is to measure the installed fastener with a micrometer, if possible, and compute torque coefficient K as follows, per Shigley, op. cit., p. 345, para. 2.
K = T L/(E A delta D) (Eq. 4)
where T = bolt installation torque, L = bolt grip length, E = bolt modulus of elasticity, A = bolt cross-sectional area, D = bolt nominal shank diameter, and delta = measured bolt elongation in units of length.
Ah well, some of the formulas didn't turn out too well, but I think you get the picture. Most torque specs are for unlubricated hardware!
Typical Steel Bolt 0.20
Zinc-Plated 0.20
Lubricated 0.18
Cadmium-Plated 0.16
Nonplated Black Finish 0.30
Question: How is bolt installation preload calculated?
Answer: Bolt pretension, also called preload or prestress, comes from the installation torque T you apply when you install the bolt. The inclined plane of the bolt thread helix converts torque to bolt pretension. Bolt preload is computed as follows.
Pi = T/(K D) (Eq. 1)
where Pi = bolt preload (called Fi in Shigley).
T = bolt installation torque.
K = torque coefficient.
D = bolt nominal shank diameter (i.e., bolt nominal size).
Torque coefficient K is a function of thread geometry, thread coefficient of friction t, and collar coefficient of friction c. Look up K for your specific thread interface and collar (bolt head or nut annulus) interface materials, surface condition, and lubricant (if any). ("Torque specs for screws," Shigley, and various other sources discuss various K value estimates.) If you cannot find or obtain K from credible references or sources for your specific interfaces, then you would need to research to try to find the coefficients of friction for your specific interfaces, then calculate K yourself using one of the following two formulas listed below (Shigley, Mechanical Engineering Design, 5 ed., McGraw-Hill, 1989, p. 346, Eq. 8-19, and MIL-HDBK-60, 1990, Sect. 100.5.1, p. 26, Eq. 100.5.1, respectively), the latter being far simpler.
K = {[(0.5 dp)(tan + t sec )/(1 – t tan sec )] + [0.625 c D]}/D (Eq. 2)
K = {[0.5 p/] + [0.5 t (D – 0.75 p sin )/sin ] + [0.625 c D]}/D (Eq. 3)
where D = bolt nominal shank diameter.
p = thread pitch (bolt longitudinal distance per thread).
= thread profile angle = 60° (for M, MJ, UN, UNR, and UNJ thread profiles).
= thread profile half angle = 60°/2 = 30°.
tan = thread helix angle tan = p/( dp).
dp = bolt pitch diameter.
t = thread coefficient of friction.
c = collar coefficient of friction.
D and p can be obtained from bolt tables such as Standard Metric and USA Bolt Shank Dimensions.
The three terms in Eq. 3 are axial load component (coefficient) of torque resistance due to (1) thread helix inclined plane normal force, (2) thread helix inclined plane tangential (thread friction) force, and (3) bolt head or nut washer face friction force, respectively.
However, whether you look up K in references or calculate it yourself, the engineer must understand that using theoretical equations and typical values for K and coefficients of friction merely gives a preload estimate. Coefficient of friction data in published tables vary widely, are often tenuous, and are often not specific to your specific interface combinations and lubricants. Such things as unacknowledged surface condition variations and ignored dirt in the internal thread can skew the results and produce a false indication of preload.
The engineer and technician must understand that published K values apply to perfectly clean interfaces and lubricants (if any). If, for example, the threads of a steel, zinc-plated, K = 0.22, "dry" installation fastener were not clean, this might cause K to increase to a value of 0.32 or even higher. One should also note that published K values are intended to be used when applying the torque to the nut. The K values will change in relation to fastener length and assembly running torque if the torque is being read from the bolt head.
One should measure the nut or assembly "running" torque with an accurate, small-scale torque wrench. ("Running" torque, also called prevailing torque, is defined as the torque when all threads are fully engaged, fastener is in motion, and washer face has not yet made contact.) The only torque that generates bolt preload is the torque you apply above running torque.
A few more things to be aware of are as follows. Bolt proof strength Sp is the maximum tensile stress the bolt material can withstand without encountering permanent deformation. Published bolt yield strengths are determined at room temperature. Heat will lower the yield strength (and proof strength) of a fastener. Especially in critical situations, you should never reuse a fastener unless you are certain the fastener has never been yielded.
1.1 Bolt Preload Measurement
If a more accurate answer for bolt preload is needed than discussed above, the specific combination and lubricant would have to be measured instead of calculated. Measurement methods are generally involved, time-consuming, and expensive, and are beyond the scope of this article. But perhaps one of the simplest and least expensive methods, to test specific combinations and lubricants, is to measure the installed fastener with a micrometer, if possible, and compute torque coefficient K as follows, per Shigley, op. cit., p. 345, para. 2.
K = T L/(E A delta D) (Eq. 4)
where T = bolt installation torque, L = bolt grip length, E = bolt modulus of elasticity, A = bolt cross-sectional area, D = bolt nominal shank diameter, and delta = measured bolt elongation in units of length.
Ah well, some of the formulas didn't turn out too well, but I think you get the picture. Most torque specs are for unlubricated hardware!
08-02-2005, 08:28 AM
#20
Race Director
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Originally Posted by Joe C
i never let tire monkeys use an impact wrench on the corvettes. when i have tires mounted and balanced, i always take them off the car, throw them in the truck, and take them to the tire place. i always use a torque wrench, star pattern, dry, torque at 50#, 75#, and finally 100# - and a recheck within 100 miles.
