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Old 02-03-2016, 03:24 PM   #8
hatzie
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Location: Wentworth, NH
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Re: What is the grade of steering box mounting bolts?

Quote:
Originally Posted by rich weyand View Post
The issue with using grade 5 and grade 8 bolts is one of torque specs. You need to torque bolts to where they deform a bit in order for them to stay tight. To do that with grade 5 and especially grade 8 bolts requires that they be torqued much more.

From this chart, a 7/16-14 (which is 7/16 NC) in grade 2 takes 24 ftlbs, in grade 5 takes 37 ftlbs, and in grade 8 takes 52 ftlbs of torque to be considered torqued up. The question then is, what kind of threads are you torquing it into, and can they take that?

It's not just a simple issue of "more is better".

https://www.boltdepot.com/fastener-i...ed-Torque.aspx
Quote:
Originally Posted by 65 C20 View Post
Captain Fab has been making and selling power steering brackets for years and supplies grade 8 bolts in his kits.
I am just saying.
You say you have already had one break, why go with cheaper bolts ?
Boy... Folks don't listen do they.
It's not a question of cheaper or more expensive... or even Mores' law.
The threads in the Cast Iron steering box may not put up with the torque necessary to properly tighten Grade 8 bolts.
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RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials...Please include at least the year and model in your threads. It'll be easier to answer your questions.
And please let us know if and how your repairs were successful.
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