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Lug Nut Issues

bonnie_rickbonnie_rick Posts: 115
edited March 2014 in General
in the News and Views Conferences' Over-tightened
Wheel Lug Nuts (Topic #291)
.

Catch up and come back here to continue!

Bonnie Rick
Town Hall Community Manager, edmunds.com
«1

Comments

  • vivonavivona Posts: 410
    This conference started with my posting that I had the wheels on my new car balanced and they used an impact wrench to install the wheels. Go back to the News & Views Conference (Topic #291) for details.

    Using an impact wrench will grossly overtighten lug nuts and lead to damaged alloy wheels, warped brake rotors and stripped lugs/nuts. Also, if you ever want to change a tire using hand tools, forget it! In extreme cases, the overtightening can stretch the lugs and lead to breakage and the wheel will fall off while you are driving.

    I have dealt with this improper practice for many years and want to take a crack at trying to stop it. Most people are unaware of the problem. The next time you have tire work done, watch the mechanic. He will remove and replace your wheels with a compressed air powered tool called an impact wrench. He may tell you he will use a torque wrench or torque stick to correctly torque the nuts when he is done, but he typically does so AFTER he has already overtightened the nuts with the impact wrench. Obviously, the mechanic just doesn't understand that the torque wrench doesn't unloosen nuts that are already too tight.

    If you do some of your own work and have a torque wrench, set the wrench to the ft lbs recommended for your wheel nuts (see owners manual, typically 80 ft lbs for a car) and try to remove the nuts. Keep increasing the setting until the nuts first start to come loose. Read the torque. That is the torque at which they were tightened to the last time the wheels were installed. I find that the tire shops will typically tighten to 120 to 200 ft lbs, that's way too much. Caution, if you do this test, don't remove all the nuts if the weight of the car is still on the wheel or it will come off! Retighten each nut to the proper torque.

    I am trying to influence industry groups to better educate tire mechanics. I may also approach NHTSA and similar safety groups. What I need are your comments and stories here in this topic.

    So, let's here the horror stories, comments, suggestions, etc.

    Are you torqued off? Did some lug give you a wrenching feeling? Are you tire-d of this practice?
  • C13C13 Posts: 390
    One note:
    I believe that if you use a click-type torque wrench to loosen the bolts, you'll mess up its calibration. Someone said this here earlier.
  • vivonavivona Posts: 410
    Some click type wrenches are designed for tighten only and some are racheted for use both ways. I have a Craftsman that is designed for use in both directions. When you hit the desired torque, all you are doing is unseating the head from a resting socket it is held into by a spring. It doesn't care which way you turn it.

    Perhaps there may be some slight affect on calibration (my instructions do not say such a thing) but we are talking a small amount. For general use, being +/- 5% is sure much better than being way off the mark. Most torque specs are in a +/- 10% range, i.e. 65-80 ft lbs, so I wouldn't worry about affecting the calibration unless you were wanting to keep your click type wrench within extreme accuracy. And if you did, you would sent it out regularly for recalibration.

    So I contend that you can go ahead and use a click type torque wrench to check torque by unloosening a nut, provided that it is designed to be bi-directional.
  • C13C13 Posts: 390
    You might be right. Just to be safe though, I'll just assume that they're torqued to criminally high values by the local vo-tech dropout, and take em off with a breaker bar and put em back on with Mr. Snap-On.

    Incidently, I finally did this yesterday after 2 weeks of neglect since I got my new tires. I feel much better now.

    PS Part of the super-high reading you get is gonna be due to the pre-load effect of the rim; like a lock washer.
  • gusgus Posts: 254
    I have a torque bar, and I use a 3/4" drive air gun to put on lug nuts. Note: when I tighten the lugnuts with the torque bar, I use only the torque bar. I usually use the torque bar only on the front wheels, because that's where you're most likely to experience any problems due to overtightening. Over-tightened lugnuts (or unevenly tightened lugnuts) will help cause the brake discs to warp.

    Tomorrow (or soon, at any rate), I'll try to find out how tight torque bars and impact guns really get lugnuts. The experiment will be conducted on Volvos and Toyotas. If I haven't posted results by Saturday, please remind me, and I'll do my best to get something up by Monday evening.
  • geo0791geo0791 Posts: 10
    C13,

    I work as a quality technician for a company that manufactures hydraulic pump and motors. We have over one hundred snap-on torque wrenches to keep calibrated on 6-9 month intervals. The "click" type wrenches are designed to torque both clockwise and counterclockwise but are not designed to break fasteners loose. I quote from the snap-on catalog:
    "Use of torque wrenches to break fasteners loose may cause overload." To be safe, I would use a breaker bar to loosen the lug nuts.

    Snap-0n certifies accuracy on it's click type wrenches is +/- 4% CW and +/- 6% CCW of any setting within the upper 80% of scale.

    I have seen wrenches out of calibration by as much as 20% due to miss use.
  • vivonavivona Posts: 410
    I agree that a torque wrench shouldn't be used beyond its rating as a breaker bar. But if a torque wrench is used within its rating, I say that is okay. For instance, if a nut is tightened to 80 ft lbs and you set your wrench to 90 and the nut comes loose before clicking, that is okay. If the wrench clicks and you continue to pull on the handle to unloosen the nut, that is not okay.

    Note to C13 reply: I have never experienced an unusually high reading due to the starting torque. I can tighten a lug nut to 80 ft lbs and come back a day, week or year later and it will click at setting of 80 and untighten at a setting of 85. It would have to be rusted or corroded on for there to be much more starting drag. And I am talking about overtightening to 150 to 200 ft lbs here. There is no way that the starting drag upon unloosening can cause a nut tightened to 80 to require 150 ft lbs to untighten.

    As to checking torque on front wheels only, I would recommend that it be checked on all wheels. You can warp drum brakes, too. And many cars have disks on the rear. Besides, overtightening can lead to stripped threads, broken lugs, alloy wheel damage or a wheel that can't be removed by hand tools in the event of a flat tire on the road.
  • C13C13 Posts: 390
    Interesting.

    Speaking of misuse, I've seen torque wrenches used as hammers. Also, the manager at that same shop (not an automotive shop) would very firmly chastise an employee who didn't use a torque wrench when he was supposed to, but the wrenches were all set at different values for the same task (like it matters, once it's been used to hammer). I asked the manager what they should be set at and he had no idea what I was talking about.

    Just a little story I like to bore people with. Has nothing to do with the present subject.

    I bought my 3/8 Snap-on clicker at a pawn shop. Very new-looking, in a case. I guess I need to get it calibrated though.
  • gusgus Posts: 254
    Okay, I re-read my post, and I meant to say that I use a 1/2" drive impact gun (3/4"?! What was I thinking?!)

    I tried testing a 7-series Volvo with aluminum wheels today, and you know, C13 is right. There is just too much pre-load on the lug nuts to get an accurate indication of how tight they are (if you're backing them off with a torque wrench). I could try to start at 80 lbs. and work my way up in 10lb. increments until I got the nut to tighten some more, but that would do more harm that good--I wouldn't want to strip the studs or damage the wheels. I really couldn't come up with an adequate way of measuring just how tight the nuts were, coming off or going on! So, I began to think about why lug nuts need to be torqued properly.

    Lugnuts need to be torqued properly for several reasons. First, they need to be torqued uniformly, so that the brake rotors, as they heat up, won't become warped. Second, they need to be torqued properly so that the holes in the wheels won't be totally chewed up. Different rims will require different torque specs. Steel rims can generally stand a greater amount of torque, and aluminum/alloy rims require less torque. I think that if the nuts are torqued properly, then a person changing his/her tires should be able to undo the nuts with a standard tire iron.

    I will keep on looking into this.
  • geo0791geo0791 Posts: 10
    I recently rotated the tires on my 98 Intrigue. I used a snap-on torque wrench to torque the lug nuts. Most wheels have a torque spec of 80 ft lbs but these chrome alloy wheels are specified to be 100 ft lbs in the owners manual. The owners manual also states that lubricant should not be used on the threads because the wheels could possibly loosen. I followed their direction and did not use lube. I usually put some anti-seize compound on the threads. The treads being dry caused difficulty in getting the proper torque because the lug nut did not tighten smoothly but had a great deal of sticktion. The lug nut would tighten in sporatic jumps. I was using a dial type wrench and I had to constantly reset the zero as these jumps would bounce the pointer past the proper setting. I think next time I will put some anti-seize on the nuts anyway. Anyone else have a solution for this problem?
  • C13C13 Posts: 390
    Gus:
    Wow, I was right about something mechanical. Now I feel better about typing on this lop-sided desk. I swear I measured carefully and used a square and everything. I blame my tools.

    geo:
    That's an interesting question. I can't imagine that there could be a problem with Loctite, the right one, whichever one it is. That's probably got enough anti-seize but also some 'glue', so to speak. I probably wouldn't risk using plain anti-seize on lugs. My racing buddies safety wire everything, though I guess that wouldn't be too practical.

    I wonder if anybody's tried 2 nuts per lug (the first one is not capped, obviously), the second one to lock the first? Then there are those clips, like on a motorcycle axle. Some vandal used to keep pulling my front axle clip out on my old Yammie. Never caught him. Had to carry spares. May he suffer eternal torment.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaPosts: 64,490
    I think if you just clean the threads with a wire brush they'll be fine.

    Often lubricant is not recommended on fasteners that are torqued because the lubricant gives you a false reading or in the case of aluminum, might allow you to overtorque before you realize what you've done.
  • vivonavivona Posts: 410
    Gus, I would suggest you do try the process of starting at 80 and increasing in 10 ft lb increments. You cannot hurt a nut or lug by applying force to unloosen it. It is the overtorqueing while tightening it that does the damage. I am surprised you found problems with measuring torque on lug nuts. Maybe the nuts or wheel holes are roughened up and are causing undue friction. Or maybe the threads are damages.

    On many cars over many years, I have always been able to use a torque wrench to tighten the nuts to the proper torque and come back immediately, a week later or a year later and use the progressive torque setting to measure how tight the torque was. I just did that with my new car. I had torqued the lugs to 80 ft lbs. A week later I set the wrench to 75 and it clicked before the nut unloosened. At 80 some nuts would loosen, some would click the wrench. At 85, all nuts would unloosen.

    I just can't imagine a nut being tightened to 80 requiring twice that to unloosen due to pre-load.

    A lug and nut in good order should be easy to tighten by hand until the nut hits the wheel. If it is hard to turn, the threads have been damaged by improper handling (over torque, cross-threading). Cleaning up with a wire brush, or better yet, a thread file, can help. Even a messed up thread only ads 1 to 5 ft lbs of drag. You can verify that by using a dial-type torque wrench to install the nut. It is also important to make sure the surfaces where the nut and wheel make contact are clean and smooth. If not, smooth them gently with a file or crocus cloth. Manufacturers warn against oil on the treads, but say anti-seize is okay. Not loctite to hold the bolt in place, but anti-seize to prevent corrosion or rust, though I have never seen a nut rusted in place.

    Though all of this conversation is interesting, the main point of this topic is the issue of mechanics grossly overtorqueing lug nuts to the point of damage, warping, lug stretching/breaking, etc. What we need to do is prevent the problem at the source. Demand that all tire work is done with hand tools and that nuts are torqued tight with an accurate torque wrench. It's your car.
  • geo0791geo0791 Posts: 10
    vivona,

    You made some very good points in that last post. Next time I rotate my tires I will apply a little anti-seize compound to make them tighten smoother.

    My daughter has a 98 Pontiac Grand Prix GT. She took it in for service yesterday to have the wheels aligned and an oil change. I told her to stop over after she picked up the car and I would check the torque on her lug nuts. First off they did a poor job of alignment because they only did the front end. The torque varied to loosen the lug nuts from 60 ft lbs on the left side to 200 ft lbs on the right. The right side varied in itself from 100-200 ft lbs! If that don't warp a rotor, nothing will. I told her to ask the service department if they torqued to the proper spec. They told her that they did and used a torque bar. I'm not sure what they are calling a torque bar but apparently it's a poor method. I also checked the rears while I was at it and found them to be 120-130 ft lbs but more uniform.

    To top it off, I checked the air pressure in the tires and sure enough, 42 psi in every one. The book calls for 30 psi in the Goodyear Eagles on the Pontiac and on my Intrigue also.

    What in the world is wrong with these guys that are working on our cars? This is just plain incompetence.
  • tnt2tnt2 Posts: 115
    I rotated my 33" tires on my 4x4 every oil change. I used an impact wrench with a torque bar calibrated for my trucks specs. I thought at first that these torque bars were a joke. Then I used one and measured the torque of the the nut. 24 lug nuts ranging from 79-82 lbs. with an 80# torque bar. I was sold. The way I tested was to seat and set all lug nuts with the torque bar and go back and check with a calibrated torque wrench "tightening" each lug 1# at a time until they broke sealing paint. One other note, micrometer type torque wrenches should be turned back to "0" before putting away, this will save calibration.
  • gusgus Posts: 254
    Most torque wrenches should be "dialed down" before they're put away, otherwise they'll become uncalibrated.

    geo0791: Most shops, if asked to do an alignment, will only do the front wheels. There is usually not any reason to do a rear-wheel alignment, especially on such a new car. Rear-wheel alignment usually comes into play if there's something wrong with the rear suspension--mechanical defect, accident damage, or other.
  • C13C13 Posts: 390
    Click-type shouldn't be put away with a torque value set?

    Wuh-oh.

    Be right back.
  • gusgus Posts: 254
    Not a high value...somewhere near the low end of the spectrum is fine.
  • tnt2tnt2 Posts: 115
    I do have a Snap-On dial torque wrench that does not need to be set to 0 before putting away. The wrench doesn't have springs that are under any type of preload, such as those present in micrometer type wrenches.
  • A couple of weeks after my wife had new tires put on her Grand Cherokee I decided to replace the front brakes. I replaced the brakes on the driver's side, and when I went to the passenger side, I had to take a breaker bar and put a 3' jack handle on the breaker bar to get most of the lug nuts. One of them refused to come off. The lug literally twisted into a piece of licorice. I then put the other lugs back on, drove it to the tire place and b*tched at them. They said that they have the air guns set to automatically shut off at X foot-lbs. BS if you ask me. They then made me bring the vehicle back the following weekend so that they drill/chisel the lug off. Well, when they did that they put major gouges in the aluminum wheel around the lug hole. Because of this, they gave me a free inspection and emissions test (even though my county doesn't require an emissions test and put the final set of brakes on. My wife wasn't too upset about the marks on the wheel, but I can only imagine how I would've felt if they did that to my car. I would've shot someone for sure.

    Actually, now that I think about it, we just had BOTH front rotors break on the jeep within 3 weeks of each other (about 5 months after the tires were put on.) I wonder if this is a coincidence or not??? The break was weire. If you picture a rotor, it has a raised center where the lugs go through, and a 'lower' level (if it's lying flat) where the brakes ride. Well, the raised center seperated from the lower level perfectly. Hmm, I think I might go buy a rotor and torque the lugs down to 200lbs and do some stress analysis on it to see if this was what broke them...
  • tnt2tnt2 Posts: 115
    You are right to say bs to the guys who put your tires on. Setting the air control on an impact will not properly torque the lug nuts. If they didn't use a torque bar, they caused the damage and the rotor failure.
  • arazaraz Posts: 27
    Fascinating. How much does it matter if the lugs and studs are hot, cold, or "just right"? The tire shop I go to unloosens them with an impact, but brings them up in 10 '# increments starting at 70 or so. All three of our vehicles have different torque specs. Also, I have had lugs pull thru the steel wheels on a trailer because I torqued them to the sticker value, and not what the wheel manufacturer spec'ed. I would always clean and lubricate threads before torqueing them.
  • tnt2tnt2 Posts: 115
    I wouldn't think that the temp would matter, as long as the lug and the nut are close to the same.
  • Is there a downside to putting a slight amount of oil on the threads before replacing the nuts? I have done this for years to keep the lug nuts from rusting when exposed to a salt environment over the winter months. The effect? I figure it will reduce the friction on the threads and more of the applied torque will be used to elongate the stud rather than twist the stud. Will the nuts be more inclined to lossen while driving? They haven't yet. I torque them to 85ft-lbs.
  • arazaraz Posts: 27
    The temp directly effects the length of the stud. The warmer, the longer. The torque effects the "stretch" of the stud. If you torque them to a value when they're cold, the studs elongate when warmed, and if the wheel is made of a different material, it may not expand at the same rate. Conversely, if torqued at high temp, they'll get "tighter" as the assembly cools. Nitpicking I think, but for purists, significant.
    Most good machinery manuals spec torque values for both clean and dry threads, and clean and lubricated threads. My only problems with lugnuts has been when there was 35% or more difference between the correct value and the one it was torqued to. The charts up here are for clean dry threads, and specific to each vehicle, with stock wheels and nuts.
  • vivonavivona Posts: 410
    Because the shop grossly overtightened my lug nuts, most of the nuts now are not easy to unscrew off the lug with my fingers once they are unloosened. The overtorqueing damaged the treads in the nuts and/or lugs. I got the shop to give me a new set of lug nuts. I plan to replace all the lug nuts, but wonder if I should clean up the threads on the lugs first. I could either run a die up each lug or use a thread file. Anybody have any experience on this? Comments?
  • GroveGrove Posts: 9
    I have 31x10.50 tires on my 99 Jeep Wrangler. My
    problem is: on almost full turn of the wheels the
    front tires will rub on the inside wheel well. My
    question is: will wheel spacers be a good idea ?
    I have heard that the spacers will make my lugnuts loosen. Has anyone heard of this or have used spacers ??
  • C13C13 Posts: 390
    I would rather go to a smaller tire than experiment with shims.
  • gusgus Posts: 254
    I agree with C13.

    #26>It probably doesn't matter which one you use, although if the stud is really, really chewed up, a file may not do you much good. Once you've done that, run the nuts backwards over the lug stud to see how freely they turn. If the stud isn't entirely clean, you'll feel it without messing up the first few threads of the lug nut. This may be impossible if you have closed-end lug nuts!! Good luck!
  • vivonavivona Posts: 410
    I guess the reason that mechanics routinely overtighten lug nuts is that few owners are aware of the problem. And even those in the know have come to accept it as just one of those things you live with. Notice how many posts this topic has received as compared to what wax or oil to use.

    I did write the manufacturer of my car to complain about the overtightening of my wheel lug nuts. I finally heard back from them today. They agreed 100% with me and said they try to get mechanics to properly torque lug nuts, but it takes constant reminding. Old habits are hard to break.
This discussion has been closed.