Posted by Clint Dixon [172.68.90.97] on Wednesday, May 16, 2018 at 13:12:57 :
By nature I have always been one who needs to know the “why” of something. Not just that it works, but why does it work, or sometimes more specifically, why does this other way not work? So I could not help it, I had to go and do some research on U-bolts. Answers to my questions are not easy to find. From what I read on the sites of aftermarket manufactures, it appears they want me to know what they want me to know, not necessarily to give me the answers to all of my questions. I don’t find this all that surprising in that I feel we have become a throw-away society with priorities geared more towards political correctness, expiration dates, and litigation. If I were making and selling lightbulbs in today’s world, I would probably want them to last only a predetermined amount of time so customers would have to buy more to replace them, and, I would want customers to hire licensed electricians to install them.
As far as aftermarket U-bolts from reputable suppliers, quality of material, tensile strength, yield strength, and proof load does not seem to be an issue. Their cautions all seem to focus on the rolled threads themselves. My boss, who used to own a certified driveline service, asked, “If they are using rolled threads on the bolts, why aren’t they using rolled threads in the nuts.” So far I have been unable to determine whether the supplied tall nuts have rolled threads or cut threads.
I specify cut threads - major diameter, minor diameter, pitch diameter, tolerance class, and inspect with micrometers, pitch mics, go-no-go gages, and ring gages – all on a daily basis. But we are not set up for manufacturing rolled threads so I know very little about their characteristics. However, I suspect if there is thread deformation after tightening to a proper torque, then it may be by design.
I have had new U-bolts made per order in the past and have had the opportunity to be present when the technician pulled a pre-threaded rod of a predetermined length off the shelf and cold press bent it to my specifications. I am not a fan of that method. However, these were not for an axle and leaf spring assembly so I was not overly concerned about the misshapen saddle and stresses from the bending process.
I did inspect the U-bolts on my WDX and B3PW. When it comes to OEM U-bolts found on our old Dodges, verses new aftermarket U-bolts, we are unfortunately comparing apples to oranges. I find, at least on my two trucks, the U-bolts are forged complete from end to end. Not just the saddle area. They also appear to have been forged complete to shape in an initial operation, trimmed to length in a second operation, and threaded in a third. Also the threads are definitely cut threads – not rolled. In fact, the major thread diameter actually measures smaller than the initial shank diameter, something that is impossible with a rolled thread.
So when it comes to my disposable daily driver, I will continue to have a technician replace the U-bolts when he removes them, replace the radial tires when they are 6-years old, and change the shocks when they wear out. As far as my old Power-Wagons, they were designed with shock absorbers that could be rebuilt, bias ply tires, and cut thread U-bolts. I will probably continue to....cut it short here....because I have to go check the expiration date on my gasoline.
;^)
Junior
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