Quote:
Originally Posted by HO455
Remember these numbers were generated by GM when these trucks were new for the dealers to make safe repairs. In addition parts and procedures were developed to make assembly line processes fast and as cheap as possible. I believe that GM designed the control nut threads to have an interference fit thus negating the need for cotter pins, lock tabs, or other mechanical device to secure the nuts quickly and permanently. By using a high torque value to slightly expand the control arm threads the nut would be locked in position.
If the nuts were ever removed then there would be no need to torque them that tight again as there the interference fit could not be achieved a second time. Hence a lower torque number for reassembly. If you look at the threaded portion of the control arm it is plain to see that there is not enough material there to withstand over torquring of the nut. Which leads us to the welding of the nuts. How many to times were these nuts tightened down with an impact wrench resulting in thread damage by guys hustling to beat shop rate? A quick tack weld would ensure no customer returns after the nut backed off and no need to take the time to get the torque wrench out.
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Thanks for the explanation! It seems the factory control arms should have been a one time use time of part since it is sorta like a torque to yield type of thing. But a tack weld would get the owner another usage without the expense though. I might just re-tack the upper control arms that I have since that will fix it.