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Old 11-04-2007, 08:48 PM   #22
Evan
Scooby Specialist
 
Member#: 11218
Join Date: Oct 2001
Chapter/Region: SCIC
Location: Orange, CA
Vehicle:
2005 Legacy GT Wagon
99 Miata, 91 Miata turbo

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Quote:
Originally Posted by Patrick Olsen View Post
3?! Yikes! That's not even remotely enough. Based on which engineering guidelines you look at, the recommendations of minimum thread engagement range for a fastener loaded in tension are generally in the 3/4 of the thread size to 1-1/2 the thread size. So for a 12mm wheel stud you're looking at 9mm - 18mm of thread engagement. (I don't think even the stock bits would give 18mm, so that's probably a bit high for our application.) So, at the low end of the range, 9mm divided by the 1.25 thread pitch gives 7.2 turns. There's not a chance in hell I'd trust 3 turns on my lugnuts!!


And hello outside shoulder wear because of 0 camber!
Thanks for the correction. McGard has a similar recommendation: "minimum thread engagement must be equal to the thread diameter of the wheel stud."

http://www.mcgard.com/custserv/tech_support.asp

So, that would equate to 9.6 turns. I thought 3 sounded pretty small, hence my caps on the MINIMUM part.
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