Lug nut Torquing
09-20-2005, 11:02 AM
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Improper torquing can cause a host of issues from a wheel eventually falling off to not being able to remove a wheel when needed to a number of things in between.
If you don't torque them enough, they can come loose and eventually fall off which can lead to all sorts of nasty incidents.
5 Meg video (right-click and save-as) There were extenuating circumstances in this incident, such as using washers as spacers and studs that were too short for the nuts to properly engage, but the same thing can happen to any car on the street if the wrong set of circumstances occur.
The bolts/studs and/or nuts can deform if too little or too much torque is applied which can cause similar failures.
If you apply too much torque (or a tech pounded the nuts on to 300 ft lbs with an impact gun), you might have a problem if you have to change a tire in the middle of nowhere and can't find anything to use as a cheater pipe (with the really short wrench included in the car's tool kit).
Don't take this as an absolute, but for the most part, you shouldn't have to worry with most car/wheel combos if they are torqued somewhere in the basic range of 80-100 ft lbs. Also, be aware that most places that will take your wheels off and put them back on (whether it's dealer service, a tire place, a gas station, brake place, etc) are going to use an impact gun to slam the nuts back on and are NOT going to hand torque them unless requested (and even then, many will only actually do so if you stand behind them watching). If you're lucky, they will put the nuts on by hand before using the gun so they won't cross thread them, but things don't always happen that way. Even when torquing, if your torque wrench isn't calibrated or used properly (particularly with extensions), what you have it set to may not be the actual torque being applied when it indicates that you're applying the amount of force you want.
Keep in mind too, that repeated removal and reinstallation of wheels can cause problems with the nuts and studs or bolts. Dirt and metal shavings (from the wheel and the threads of the bolts, studs, nuts themselves) can get in there and gall up the threads. If you check and clean them each time the wheels come off, you can minimize the potential for damage and inconvenience later. Cheap, low quality lug nuts (like those that come on the RX-8 and Miata) don't help.
If you don't torque them enough, they can come loose and eventually fall off which can lead to all sorts of nasty incidents.
5 Meg video (right-click and save-as) There were extenuating circumstances in this incident, such as using washers as spacers and studs that were too short for the nuts to properly engage, but the same thing can happen to any car on the street if the wrong set of circumstances occur.
The bolts/studs and/or nuts can deform if too little or too much torque is applied which can cause similar failures.
If you apply too much torque (or a tech pounded the nuts on to 300 ft lbs with an impact gun), you might have a problem if you have to change a tire in the middle of nowhere and can't find anything to use as a cheater pipe (with the really short wrench included in the car's tool kit).
Don't take this as an absolute, but for the most part, you shouldn't have to worry with most car/wheel combos if they are torqued somewhere in the basic range of 80-100 ft lbs. Also, be aware that most places that will take your wheels off and put them back on (whether it's dealer service, a tire place, a gas station, brake place, etc) are going to use an impact gun to slam the nuts back on and are NOT going to hand torque them unless requested (and even then, many will only actually do so if you stand behind them watching). If you're lucky, they will put the nuts on by hand before using the gun so they won't cross thread them, but things don't always happen that way. Even when torquing, if your torque wrench isn't calibrated or used properly (particularly with extensions), what you have it set to may not be the actual torque being applied when it indicates that you're applying the amount of force you want.
Keep in mind too, that repeated removal and reinstallation of wheels can cause problems with the nuts and studs or bolts. Dirt and metal shavings (from the wheel and the threads of the bolts, studs, nuts themselves) can get in there and gall up the threads. If you check and clean them each time the wheels come off, you can minimize the potential for damage and inconvenience later. Cheap, low quality lug nuts (like those that come on the RX-8 and Miata) don't help.
Last edited by clyde; 09-20-2005 at 11:05 AM.
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