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anti seize question

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  • Joe L.
    Beyond Control Poster
    • February 1, 1988
    • 43193

    #76
    Re: anti seize question

    All------


    From a table of "Standard Torque Values", the torque value for 7/16-20 grade 8 bolts with LUBRICATED threads is 62 pound/feet. So, if one applies lubricant to the threads and torques the nuts to 62 pound/feet one will meet this spec and also be within the GM torque value range for the studs.
    In Appreciation of John Hinckley

    Comment

    • Joe L.
      Beyond Control Poster
      • February 1, 1988
      • 43193

      #77
      Re: anti seize question

      Originally posted by Michael Hanson (4067)
      When I lived in the frozen north, with all the salt on the roads, I coated the wheel studs and nuts on my Blazer with SP-350, a cosmoline/parafin rust preventative.

      I didn't drive my Corvette in the salt though.

      Michael------


      I think you probably did drive the car in the salt. You may not have driven it in the winter, but that doesn't mean you didn't drive it in the salt. In areas where salt is used on the roads, the salt doesn't all go away when the snow and ice go away. Snow and ice drain away but all of the salt doesn't go with it. Some stays on the roads and, especially, on the "winter leftovers" that accumulated on the sides of the roads. When it rains, it re-dissolves and wreaks the same havoc on steel car parts as it does in the winter. It does not take too much salt to get corrosion started and, once started, it proceeds inexorably.

      I have seen cars from the northeast that were never driven in the winter from the day they were new but still evidenced body or frame rot after a number of years. A 1957 Corvette I recall was among these.
      In Appreciation of John Hinckley

      Comment

      • Michael H.
        Expired
        • January 29, 2008
        • 7477

        #78
        Re: anti seize question

        Originally posted by Joe Lucia (12484)
        Michael------


        I think you probably did drive the car in the salt. You may not have driven it in the winter, but that doesn't mean you didn't drive it in the salt. In areas where salt is used on the roads, the salt doesn't all go away when the snow and ice go away. Snow and ice drain away but all of the salt doesn't go with it. Some stays on the roads and, especially, on the "winter leftovers" that accumulated on the sides of the roads. When it rains, it re-dissolves and wreaks the same havoc on steel car parts as it does in the winter. It does not take too much salt to get corrosion started and, once started, it proceeds inexorably.

        I have seen cars from the northeast that were never driven in the winter from the day they were new but still evidenced body or frame rot after a number of years. A 1957 Corvette I recall was among these.
        Details, details.

        Actually, you are more correct than you know. I drove the brand new 64 coupe in the salt every day all winter long for two years.
        I drove various 63-67 Corvettes every day of every winter for many years.

        It wasn't until about 1974 that I finally stopped using these cars as daily drivers.

        I agree on the salt dust. In the spring, the roads would stay white even when dry until a few rain storms.
        The salt residue and dust on the frame would reactivate when the car was parked in a damp garage. On a quiet night, you could hear the frame rusting.

        Comment

        • Jim T.
          Expired
          • March 1, 1993
          • 5351

          #79
          Re: anti seize question

          Originally posted by Michael Hanson (4067)
          I think someone mentioned earlier in this thread that it would probably be safe to go with lubricated threads but stay with the low side of the torque spec. I think I agree with that.

          I don't remember the formula for the reduction factor and I can't find it now. Been looking for it for two days. It's here somewhere in all this rubble.
          I was looking forward to seeing the formula for the reduction factor. Put the two front wheels back on my 96 LT4 this evening and for the first time since it was new, I used anti-sieze lubricant. My lugs and bolts are like new and I am the only one that has removed/installed them since the car was purchased new. I always used 100 ft lbs torque before (3 times). Using the torque wrench tonight, I set it on 100 ft lbs and stopped short of getting a click/torque break. Just felt like I was tightening a lug nut to much. Reset the torque wrench to 90 ft lbs. I am driving it on a 300 mile one way trip tomorrow.

          Comment

          • Michael H.
            Expired
            • January 29, 2008
            • 7477

            #80
            Re: anti seize question

            Originally posted by Jim Trekell (22375)
            I was looking forward to seeing the formula for the reduction factor. .
            Hi Jim,

            I haven't forgotten. I just haven't found it yet. I know I have it here somewhere because I dug it out a few years ago for a neighbor.

            Comment

            • Michael G.
              Extremely Frequent Poster
              • November 12, 2008
              • 2155

              #81
              Re: anti seize question

              Joe Mish, In the 60's, we used our lug wenches often, usually to change frequent flat tires on the side of the road (sometimes to threaten other teenagers). We'd generally put as much torque on the nut as the lug wrench would deliver. I don't think I ever broke a stud tightening it with all my strength. Since then, many millions of them have been tightened by all manner of Bubba techniques, without problems.

              That performance was not accidental. GM engineers in the 60's were not oblivious to the methods Bubba and I utilized to tighten lug nuts in the field. They supplied the wrench, note carefully that it wasn't a torque wrench. They didn't hold any false hopes of anyone actually measuring the torque on these nuts.

              Given only those two pieces of information, with no knowledge of how torque specs are established, I'd bet they engineered the stud to ultimately take the tension delivered in service by me and Bubba, but set the minimum production spec to deliver slightly above the minimum tension that what was necessary to hold things together. These two values are likely to be very far apart, deliberately.

              Having set thousands of GM torque specifications, I'm pretty sure that's reasonable scenario. As such, there is likely to be a significant "safety" gap between the upper end of the production tension range and the yield point of the fastener. That gap means that today, if we decrease the friction in the joint slightly, it will likely only increase the the tension within an acceptable range, still not approaching yield. So, anti-sieze is probably OK. It also means, though, that if me and Bubba use anti-seize, we can no longer use our muscles or air wrench, we need to to use the design torque!

              (Note that this is theory, if somebody really needs to know the answer, get me a couple dozen original studs and nuts and I''ll test 'em.)

              The other part of this is fastener finishes. They apparently engineered this attachment to have very high friction (maybe that was an accident). The fact that it is difficult to do anything to this joint that will increase the friction in the threads over the design friction, means that they (and we) will never have to worry about a properly tightened, but corroded or otherwise adulterated joint, having less tension than expected to keep it together. If that was a accident, it was a very smart one, because it means that unavoidable corrosion (or dirt) doesn't hurt a thing.

              Also... I don't think Cadillac ever had wheels falling off in the 80's due to lug nut or wheel stud issues (and I'm pretty sure I would have been informed)

              Comment

              • Terry M.
                Beyond Control Poster
                • September 30, 1980
                • 15573

                #82
                Re: anti seize question

                This is a recurring, heated topic over on BITOG (Bob is the oil guy). They have torque reduction numbers in the 20% range for lubricated threads, and they cite many Internet sources. But then you can always believe what you read on the Internet, right?
                Terry

                Comment

                • Dick W.
                  Former NCRS Director Region IV
                  • June 30, 1985
                  • 10483

                  #83
                  Re: anti seize question

                  One thing that has been left out of this discussion is the accuracy of your torque wrench. I have mine calibrated every few years and have had the results come back showing up to 20% error down to 0%.

                  A cheap torque wrench probably is not real accurate when new, let alone being accurate 10 years later.
                  Dick Whittington

                  Comment

                  • Michael H.
                    Expired
                    • January 29, 2008
                    • 7477

                    #84
                    Re: anti seize question

                    Originally posted by Dick Whittington (8804)
                    One thing that has been left out of this discussion is the accuracy of your torque wrench. I have mine calibrated every few years and have had the results come back showing up to 20% error down to 0%.

                    A cheap torque wrench probably is not real accurate when new, let alone being accurate 10 years later.
                    Good point. Soooo.... if your wrench is 20% off, on the lean side, and you torque the lug nuts to an 80# setting on the wrench, it's entirely possible that you are actually torquing the nuts to 96 lbs. (just before they snap)

                    Comment

                    • Jim L.
                      Extremely Frequent Poster
                      • September 30, 1979
                      • 1805

                      #85
                      Re: anti seize question

                      Originally posted by Michael Garver (49693)

                      4. While freely spinning a nut all the way onto a stud (once) prior to torquing will likely improve the consistency of the torque tension relationship, multiple loaded assemblies or "Conditioning" a thread alters its friction significantly and will not re-create the desired design condition.
                      I'm not following what you are saying..... or I'm just missing the point you are making.

                      If multiple tighten/loosen cycles are a bad thing (and your statement reads as if they might be), then it would imply that the specified torque values for wheel studs are meaningless after a few instances of wheel removal and re-installation.

                      No argument that multiple cycles will change the relationship between torque and tension. I've tightened enough rod bolts measuring both torque and bolt stretch to have experienced this.

                      In any event, it is for that reason that I'd do several tighten/loosen cycles on new wheel studs/nuts before I'd believe the studs are providing the intended clamping force.

                      Jim

                      Comment

                      • John H.
                        Beyond Control Poster
                        • December 1, 1997
                        • 16513

                        #86
                        Re: anti seize question

                        When I was buying assembly tooling in the 60's and 70's, before computers on the factory floor, an air-driven five-spindle lug nut multiple cost about $10,000. The Atlas-Copco DC constant-rpm electric lug nut multiples I was buying in the 90's (with torque and angle transducers and individual spindle feedback monitoring) were over $100,000 each, including the interface box that connected them to the Factory Information System network. Modern computerized electric torque tools are incredibly accurate, and heinously expensive.

                        Comment

                        • Michael G.
                          Extremely Frequent Poster
                          • November 12, 2008
                          • 2155

                          #87
                          Re: anti seize question

                          Jim, my point was that production torque specifications are established for assembly of virgin threads, parts whose mating surfaces have not been polished or abraded. Each run-down of the nut changes both contact surfaces. Sometimes it polishes them, sometimes it removes the coating. You might increase friction, you might decrease it, you never know, it depends on the combination of surface coatings you have. You're better off just assembling the parts loosly once, to remove debris and/or smooth globs of paint.

                          You are essentially correct in your statement that repeated assembly renders production torque specs "meaningless" for reassembly of wheel bolts, except that they still "mean" that you've applied some clamp load, it just isn't the same amount of "load" applied during the first assembly. Its probably higher, because, as I explained below, the fiction in the production wheel bolts is very high, so, repeated assembly can't really make it very much higher, only lower. As such, repeated reassembly (to the same torque) isn't going to reduce clamp load, it can only increase. A bit more clamp load doesn't seem to be a problem in that joint, so your effort to condition the threads aren't likely to hurt much. But, they don't help either.

                          Comment

                          • Jim L.
                            Extremely Frequent Poster
                            • September 30, 1979
                            • 1805

                            #88
                            Re: anti seize question

                            Originally posted by Michael Garver (49693)
                            Jim, my point was that production torque specifications are established for assembly of virgin threads, parts whose mating surfaces have not been polished or abraded.
                            OK, so this brings up the next (obvious?) question..... does/did the factory torque virgin threads to the same values as recommended in owners' manuals and shop manuals for service operations?

                            Jim

                            Comment

                            • Michael H.
                              Expired
                              • January 29, 2008
                              • 7477

                              #89
                              Re: anti seize question

                              Originally posted by Jim Lockwood (2750)
                              OK, so this brings up the next (obvious?) question..... does/did the factory torque virgin threads to the same values as recommended in owners' manuals and shop manuals for service operations?

                              Jim
                              Jim,

                              I just looked in the 63 AIM and the same 55-65 specification is shown.

                              Comment

                              • Michael G.
                                Extremely Frequent Poster
                                • November 12, 2008
                                • 2155

                                #90
                                Re: anti seize question

                                Jim, In general, yes. There are exceptions, such as ball joints, where the production strategy would be difficult to duplicate in service.

                                To anticipate your next question, in most cases, the difference in tension between a virgin assembly and the first or second reassembly is small, so if you set your torque wrench to the mean, your tension will still be OK on the reassembly. I wouldn't get in the habit of torquing the reassembly to either extreme of the the torque spec, though, because then the tension change might take you outside the allowable range.

                                To give you an example of what can happen, some modern finishes have teflon in one of the coats of paint. I tested a bolt thusly finished repeatedly, in the same nut. As the paint layer with the teflon wore off after several runs, the friction changed dramatically. Conditioning these threads would render the production torque spec totally meaningless. This finish isn't on old Corvette, though.

                                I hope that helps,

                                Comment

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