Wheel spacers installed with impact wrench

[20ducks]

Awesome! Thanks for the link, I'll use it and the physical manual when I pick it up at the dealer. btw, does anyone else think that 150 lb ft is high? But it is what it is. Thank you all again.

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[FreePenguin]

No. I’m on like 19k of steeda 20mm spacers all around. I torqued the specs to 150lbs per instructions. Both inside and outside lugs.

I wouldn’t feel comfortable only doing 90 or whatever. I havnt rechecked but had wheels off recently to touch a caliper w paint

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[Epiphany]

The ISO standard for a baseline fastener torque is to achieve 75% of the tensile loading required to yield the fastener. This value is a calculation based on the yield strength of the fastener material, and the minimum cross section of the fastener. Since like minor diameter of a fine thread is larger than coarse thread, the tensile load to yield the fastener is higher, and the suggested baseline torque is higher.

^^This statement is generic, and is where values in most torque tables comes from. In most applications it is adequate.

Now Ford likely performed additional calculations to validate their specified torque values, but as soon as someone changes that fastened joint be it by a wheel with a thicker flange, a spacer interface, or by having a different wheel alloy, error is introduced into those calculations. As I mentioned in my earlier post, if you go look in a torque table for a class 12.9 M14 fastener with fine thread, I bet it will be pretty damn close to 150 ft-lbs. I’d also be willing to bet Ford’s engineers calculated number wasn’t exactly 150 ft-lbs either, but it was likely close enough that 150 was chosen for convenience while still falling within a safe margin.

As for my credentials, I have a degree in Mechanical Engineering from Montana State University. My day job is designing tools, machines, and processes to produce the afterburner assembly for the F135 engine used in the F35 fighter jet. I also am a mechanic on a pro-modified car that has gone 5.81 at 250mph in the quarter mile during the summer months. Check my post history for a photo of it if you care.

A painful thread this was but the above post was superb and spot on. Well done Jason.

 

[20ducks]

I'll be using the on-line version...extremely helpful. Thanks again.

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