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Wheel Nut Torque

jmeiers

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How did you arrive at that value?
Nothing scientific at all, just my preference. I always check the torque after 25 miles or so and they remain torqued and nothing has ever come loose.
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Laserbrain

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The fact that a "Diamond Sponsor" vendor does not use factory torque specs is alarming. I'm actually glad this came up. Now I know never to take my car there.
When I change my oil, I put in 5 quarts. It just feels right and it has been more than enough on all the other cars I've owned. I don't need the owner's manual to tell me what to do.

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BmacIL

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Nothing scientific at all, just my preference. I always check the torque after 25 miles or so and they remain torqued and nothing has ever come loose.
Those silly Ford engineers,what do they know? I'm just gonna do what I believe feels good.
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\dave

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In service lugs will experience side loads, applied and removed repeatedly when driving. The repetitive loads in line with the lug axis cause the lugs to repeatedly stretch and then contract. This cycling of tension and loss of tension can cause a lug nut to work loose. To prevent that loosening, a preload (torque) is applied to put a certain amount of stretch in the lug. Without this preload, the nut may not have sufficient contact force with the wheel and work itself loose.

The preload value (torque value) is determined by several considerations, but predominantly the preload stretch needed to prevent loosening. Other considerations may apply such as local contact stresses of the lug nuts on the aluminum wheel, temperature changes, etc, etc. For many industry applications that see cyclic loads, nuts are tightened so that the bolt (lug in this case) reaches 2/3 of its yield strength. That leaves 1/3 of the yield strength value as a buffer, as going beyond the yield strength value may damage the fastener. Different rules might apply in situations where the joint is not metal-to-metal (for example where a gasket is involved).

Tensile (tension) yield strength of metals varies widely. Mild steels (e.g., a good non-Chinese hardware store bolt) are usually on the order of 30,000 psi. Hardened steels can go over 200,000 psi yield strength. I don't know what steel the Mustang lugs are made from, but they won't be mild steel.

Unless you have altered part of the assembly (for example a more ductile lug than stock) or you see evidence that Ford's specified torque is incorrect (for example, if there's a class action suit for Mustang lugs or wheels being damaged at Ford's specified torque), my advice is stick with what Ford specifies. Relax and torque away.
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