Lug Nut Torque On My '56

[Steve Westphal]

Am preparing to put the new stock rims and Coker WWW tires on my "56. How many pounds of torque should be applied to the lugs? Thanks

[Duke W.]

Re: Lug Nut Torque On My '56

I've always used 80 lb-ft on the standard GM automobile lugnuts, which I recall are 7/16-14.

Duke

[John H.]

Re: Lug Nut Torque On My '56

Steve -

A.I.M. spec is 55-75 lb-ft; they're 7/16"-20 threads.

[Christopher R.]

Re: Lug Nut Torque On My '56

I bought 4 new tires and put them on rims that I carefully prepped and painted. Now that the whole wheel looked nice, i thought I'd treat them to a torque wrench and put the lugs on at 75ft/lbs. You know, do it right. For years I put wheel lug nuts on by the grunt method, although I did tighten them progressively and on alternating sides of the rim.

Guess what? 75 ft/lbs is awfully loose. When I went to remove one a few miles later, all the nuts felt very loose. Scared me. I went back to the grunt method.

[John H.]

Re: Lug Nut Torque On My '56

That's why it pays to go back and re-check critical torque applications on freshly-painted parts; there will be some residual torque loss with a heavy paint film (like wheel enamel). One of the determining factors (these days) in establishing initial fastener torque specs which will maintain the required design clamping load is to measure residual torque 24 hours after assembly. 25+ years ago, most assembly plant power tools were impacts running on 90 psi "shop air"; these days, all critical fasteners are driven by computer-controlled DC electric nutrunners ($8,000 per spindle each, plus $2,000 each for the interface panel) that sense both torque and angle-to-yield (fastener stretch), and every cycle is reported back to the car's electronic computer record in the F.I.S. (Factory Information System); any failure to meet required parameters for safety-related fasteners will flag the car's electronic inspection record, and will prevent certification labels, price stickers, and shipping papers from being printed until the correction is performed and electronically certified. These days, "It's not your father's assembly plant" any more