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Proper Wheel Lug Tightening Proceedure

Discussion in 'Technical Q&A' started by furmano, Mar 3, 2009.

  1. furmano

    furmano Two Time F1 World Champ
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    Jul 22, 2004
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    furmano
    OK, stupid question but here goes.

    When reinstalling wheels and tightening the lug bolts what is the proper procedure? If the car is up on a jack do I tighten to a certain amount (say around 50 ft. lbs) while holding the wheel with my hand? Then lower the car to the ground and finish tightening?

    Or should all the tightening up to the specified amount (75 ft. lbs. if I remember correctly; I don't have the specs in front of me) be done while the car is in the air? Should the car be in neutral with the parking brakes off?

    Set me straight.

    Car in question is a '87 328.

    -F
     
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  3. ducowti

    ducowti Formula 3

    Jan 27, 2008
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    First, be sure to protect each bolt head (or line the inside of your socket) w.painter's tape or similar buffer to avoid nicking the points which will rust and look like crap.

    I hand tighten in crossing pattern while wheel is in air, lower the jack till the tire just touches and wrench tighten a bit in a crossing pattern, then lower it a bit more, repeat pattern, lower a bit more, repeat, lower and then torque.
     
  4. rob lay

    rob lay Administrator
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    Dec 1, 2000
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    1) Make sure all lug nuts and bolts are clean.

    2) Hand tighten several turns to reduce risk of stripping.

    3) Wrench tighten, but only about 40-50 lbs. in air.

    4) Torque to proper setting, making sure to go around a 2nd time.

    All the tightening should be a star pattern. On the ground, least movement the best and I don't mind in gear and emergency brake on, but I think strong argument to chalk the wheels and have car in neutral without emergency brake. Same reason you don't trailer a car in gear or emergency brake on.
     
  5. Gerry328

    Gerry328 Formula 3
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    #4 Gerry328, Mar 3, 2009
    Last edited by a moderator: Sep 7, 2017
    I snug the lugs in the air with my impact using the Hill Engineering Chrome Saver Socket. Then on the ground I tighten fully using a torque wrench following the patterns below.
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  6. TCM

    TCM Formula Junior

    Nov 10, 2003
    552
    Tyngsborough, MA
    Always hand tighten in air in star shaped pattern. Then torque to 50lb ft in air before lowering to let tyre contact the ground where you then apply full torque in star pattern again. Hope this helps.
     
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  8. Iain

    Iain F1 Rookie

    Jan 21, 2005
    3,220
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    Not sure of value or need to go around a second time & it actually goes to the core issue of how to use a Torque wrench properly - so many people (especially in garages/tyre shops) don't!

    To torque to proper setting you need to do it in one clean pull. If it doesn't click & you then stop & then try again and it does click without the bolt moving then you need to undo it & do it again in one clean pull.

    You need to hit the torque setting in one movement otherwise you end up dealing with overcoming the "initial moment of inertia" (I think its called!) plus the friction between the bolt & the wheel. In other words it takes a considerable amount of extra force to get a bolt turning again.

    To put it in numbers, if you have tightened the bolt to 70 and you are aiming for 75, it might take 80+ to get it moving again - which will make your T-wrench click & so its never going to work.

    Ergo, going round a second time (if you've done it properly) isn't going to help.

    What you should do though is check the bolts are still tight after 30-50 miles. Two schools of thought on this: either just run round with a torque wrench & make sure it clicks on every bolt or back them all off a bit & then re-torque. Take your pick.
     
  9. Skidkid

    Skidkid F1 Veteran
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    Aug 25, 2005
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    Rob's procedure is correct, it is done in two stages, but your point that the final torque should be in one action is also correct.

    You are talking about the difference between the coefficient of static friction vs the coefficient of sliding friction. Static friction is much higher than sliding friction so the force required to move the bolt again will be very different if you let it stop. Think about how tires hold then just release. Stopping the slide happens at condition that you would never have slid the car. Same concept.
     

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