Destructive Lock Nuts Suck

Bob La Londe · 2024-04-12T20:14:58+00:00

I recently had to install new axles on a trailer in order to get working brakes on the trailer... Don't lecture me about how you could have done this or that and not replaced them. They were oddballs and I wasted a couple weeks looking for other solutions.The u-bolts that came with the new axles came with the destructive style lock nuts. I don't mind to much. I hoped to never have to deal with this again on this trailer anyway. On my second run to go pick up a truck and haul it halfway across the state over some mountains and some modestly substantial grades and weave through the Salt River Canyon two nuts came off.When the nuts came off I don't know, but when I went over a bump the axle popped off the springs and the tire slammed into the tire behind. I had just hit 65 mph and it suddenly felt wrong. I was running empty and all of a sudden it felt like I was running with a load. I glanced at the mirror and smoke was pouring off those tires so bad I thought a hub was on fire. Fortunately, there was on old stock yard just ahead with a lot of flat ground out front where I was able to safely pull out somewhere west of Coolidge. The axle coming loose turned out to be an easy fix. Since I was still running empty I just jacked the side of the trailer up, rolled the axle back in place, and ratchet strapped it tight. Then I whipped out my cell phone and entered NEAREST HARDWARE STORE into the search window.The U-bolt that had fallen off was just barely hanging onto the axle still by the extra friction of the threads. The other U-bolt was still attached to the cross plate by the nuts. At least I wasn't wondering where in small town Arizona I was going to find U-bolts.There was a Tractor Supply store in Coolidge that had TWO (2) (just two) 9/16 fine nuts. They were in the wrong bin, but I found them. With that, a couple fresh lock washers, and copious amounts of red high strength Permatex thread locker I crawled under the trailer in the parking lot to fix it.Coming back I...

Apr 12, 2024 Last reply: 2 years ago 44 Replies

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Joe Gwinn 2 years ago

By the way, McMaster carries these. .

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Do you have any more information or URLs for FujiLok? Google didn't help because I didn't know enough to pull this out of the irrelevant hits.

Joe Gwinn

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Joe Gwinn 2 years ago

In their defense, they prove Key-Lock's vibration resistance with a Junker test, which is the gold standard. And NASA will accept no less.

Joe Gwinn

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Joe Gwinn 2 years ago

I think I found them. The company is "Fuji Seimitsu Manufacturing Co Ltd ".

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The locknut is basically the same as the Security Locknut steel insert. There is a US patent that I have not yet found, so there must be some difference.

Joe Gwinn

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Joe Gwinn 2 years ago

Not so fast. I did find an earlier Chinese patent from FujiLok that had a diagram that resembled the Security Locknut, but that is not what's currently offered:

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Somewhere in the middle of the sales talk there is a section that shows how it's built and works. But no Junker test data.

Joe Gwinn

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Clare Snyder 2 years ago

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Just google what is a fuji lock nut or how does a fuji lock nut work

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