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Over-torqued lug nuts

Discussion in 'Gen III 2010+ Prius Care, Maintenance and Troubles' started by mmichaell, Aug 31, 2010.

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  1. mmichaell

    mmichaell New Member

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    Any of you guys have this happen to you? My last oil change/rotation service my lug nuts on my 2010 Prius were torqued correctly to the 76 ft-lbs necessary, however recently on 8/27, when I checked, the 7-9 nuts that I checked were way out of spec. They were at least 85-90 ft-lbs, but I can't be sure since my wrench doesn't measure torque that high. I contacted the dealer asking for a reason for this, and haven't gotten a call back. Any of you guys have had this happen to you specifically? Just wondering how many other Toyota dealers goof in this area. Will let you all know what the dealer's response is...
  2. RRxing

    RRxing Active Member

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    I have yet to see any service department use a torque wrench on lug nuts or any other bolts/nuts for that matter. They just use a pneumatic impact wrench that is set at "who knows what?" I also seriously doubt they change the setting for every car they use it on.

    Glad to see that you checked yours. Just another thing to keep an eye on. Thanks.
  3. xs650

    xs650 Senior Member

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    If they were torqued to 76 lb-ft it is not unreasonable for it to take 85-90 lb-ft to move them at a later time. How much more or less it take to move them at a later time is dependant on several things. There is no reliable way to check the original torque at a later time.

    Torque some clean dry lug nuts onto a clean dry studs to 75 lb-ft, let them sit a day and check the torque required to move them, try some crack-on, some crack-off.
    Bolt Science Web Site
    I think the guy that wrote that article is a bit of an optimist:D, but it's still a good read.

    All that said, the torque values you found aren't all that bad. If they were looser than spec or 50% tighter, there would be reason for concern.
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  4. dogfriend

    dogfriend Human - Animal Hybrid

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    At least they tightened them enough; my dealer forgot to torque three wheel nuts on my car when they rotated the tires at 5k. I decided to check when I found that one of the valve stem caps had fallen off and another was hanging by a thread. I no longer give them any service business.
  5. mmichaell

    mmichaell New Member

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    I appreciate the replys. Just an fyi why this is a concern - if one tightens the lugs too much & unevenly, that eventually can cause the rotors to warp, causing vibration every time you brake. My last car, a '99 Civic had the factory rotors up till about 135k miles when I gave it away - but I always checked the lugs and retorqued them if there were problems & never had any vibration.
  6. qbee42

    qbee42 My other car is a boat

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    I thought this thread was about Jayman. He's an over-torqued lug nut!

    ;)

    Tom
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  7. a_gray_prius

    a_gray_prius Rare Non-Old-Blowhard Priuschat Member

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    A lot of the time the impact wrenches have torque limiters attached to them. Do different Toyota models have vastly differing lugnut torque values?
  8. xs650

    xs650 Senior Member

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    Impact wrenches ability to control torque are notoriously bad. No way I would use a shop that routinely relied on an impact wrench to set a specified torque.

    Torquesticks
    Professional torque sticks, sockets, multipliers and extension bars
    are several notches above impact wrenches in their ability to control torque. Torquesticks still aren't as accurate as torque wrenches but many people that know what they are doing find Torquesticks acceptable for lugnuts.
  9. GSW

    GSW PRIUS POWER

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    On a similar note, I like Ron Whites version of his visit to Sears Automotive. Upon leaving, his rear wheel fell off making a right hand turn. "It fell off, it fell off, IT FELL THE F**K OFF!!! :D
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  10. cit1991

    cit1991 New Member

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    When you torque a nut, you are trying to obtain a certain clamping force that holds the wheel against the hub. That clamping force comes from tension in the bolt, which also stretches it like a spring...a very very stiff spring, but it does stretch a tiny bit.

    When you apply torque to the nut, some of that torque goes toward stretching the bolt (which you want), some also goes toward overcoming friction in the threads, and some goes toward overcoming friction where the nut face rubs against the wheel.

    Some engineer calculated the amount of clamping force needed and the torques (all 3) to arrive at the torque we use when fitting a wheel.

    If you undertorque, the clamping force will be low and the nuts might vibrate free. If you overtorque, you overstretch the bolts. If the bolts are overstretched over and over, they harden and can crack. So overtightening can lead to the same failure as undertorquing (a wheel falls off).

    Another common problem is that if you use a thread lube (antisieze, oil, etc.) you lower the thread friction. This sounds great, but if you tighten to the same torque, then more torque (and force) will go toward stretching the bolt. This can also lead to hardening and bolt failure. So, you really shouldn't use thread lube, unless you have someone recalculate the tightening torque, to maintain the same clamping force.
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  11. a_gray_prius

    a_gray_prius Rare Non-Old-Blowhard Priuschat Member

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    I have aftermarket lugnuts which are aluminum rather than steel and the torque spec is different as well due to the nature of the metal-metal interface. However the difference is small.
  12. albert1028

    albert1028 Junior Member

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    Also, I believe that overtorqued lug nuts are not the end of the world since lug nuts are usually not too sensitive to being over torqued, yes I know that the lug nuts have specific torque specs, but lug on some cars, they are suppose to be torqued to 90 ft-lbs.

    I'd say not to worry, readjust them and you will be good to go.
  13. LoveMyPriusIII

    LoveMyPriusIII New Member

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    Last year after having my tires rotated on my Honda Fit I specifically asked them to tighten to spec with a torque wrench. They said ok but when I got up to look out the window at one point I saw the guy tightening the lugs with an air gun. I was upset and when I got the car home I put my torque wrench to max 160 ft-lbs and tried to loosen the lug nuts. The wrench clicked, stating I applied 160 ft-lbs of force, before the lug nuts budged. I had to give it just about everything I had to loosen them. I tightened them to spec but was very angry since I hear it can warp the rotors. Like someone else stated however, I have never seen a shop actually use a torque wrench to tighten the lugs. Anytime I ask about it they give me some story. Once they said the pneumatic wrench is set to 100 ft-lbs although I didn't see anything on the gun to adjust the torque. One guy just said he's been doing it for years and that he knows when to let off on the trigger before it torques too tight. I just can never find a place to take my cars that I feel comfortable with.
  14. drees

    drees Senior Member

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    Discount Tire around here always use a torque wrench and the appropriate setting is on the service sheet so the techs don't have to waste time looking up the proper torque setting.
  15. LoveMyPriusIII

    LoveMyPriusIII New Member

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    That's how it should be at all shops, but sadly that isn't the case. When I find one that is that way I will be taking my car there. That company took the time to setup a process to do things right.
  16. mmichaell

    mmichaell New Member

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    So, the service manager at the dealership finally got back to me. This is his response:

    Hi Michael

    I spoke with the tech regarding the over torque concern and he stated that he used a torque stick to tighten the lug nuts on your vehicle. We checked the torque stick and found it was not performing properly. We have stopped using this torque stick now. I appreciate you bringing this matter to my attention.


    So at least they looked into and recognized an issue. I was a bit worried there - if a dealer would not respond to me wrt dissatisfaction over a small issue, how about a big issue which was there fault? However they did look into it, gave me a response, so I am satisfied.
  17. SyZyGy

    SyZyGy New Member

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    Buy a decent torque wrench and do it yourself. I made the mistake of taking my evo to a mitsu stealership to have my rotors turned because I had some pretty uneven pad deposits. Usually I do everything myself, but I had no way of getting the rotors anywhere if I took them off my car, and they would be too heavy to put in a backpack and take the motorcycle because they are huge.

    The tards over-torqued the lugs so badly that I broke 1 ratchet and one breaker bar trying to get the FIRST lug off. When I broke the breaker bar, the little ball and spring that positions the chuck at different angles shot out and hit me in the face.:pound:

    First time I had someone do maintenance for me and it bit me in the ass. Never again...
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  18. drees

    drees Senior Member

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    If they are talking about a torque stick that is used on a air ratchet - those are notorious for being inaccurate and are not recommended when you want a precise torque set.

    Torquing of lug nuts should be done by hand with a wrench that is periodically calibrated.
  19. cit1991

    cit1991 New Member

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    Torque sticks work (in theory) if:

    the same impact wrench is used (not a bigger one)
    the same air pressure is used
    the same power knob setting is used on the wrench
    the impact wrench is in the same state of lubrication

    It's not a magical device that transforms any impact wrench into a calibrated torque-delivery machine.

    Since almost the above conditions are never met all the time at a tire shop, they are unreliable, no matter how good the salesman is nor how many other shops use them.

    As far as I'm concerned, they're snake oil.
  20. SyZyGy

    SyZyGy New Member

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    Also, Permatex anti-seize is your friend!;)
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