Bar Nuts Coming Off | Husqvarna 460 Rancher

[niefer]

I got my 460 Rancher stuck in a tree the other day in a bad position (completely sideways with the engine weighing down the 24" bar). After using a second saw to fell the tree I got my bar free, but it had a slight but noticeable bend in one area. I thought it could still be useable, so I reassembled everything and it worked, until all of a sudden the chain came off. When I looked down, I noticed that one of the bar nuts had come free, which had loosened the clutch cover. After reassembling everything, including synching the nuts down tighter, I tried again and the same thing happened. I decided that it must be the bar and bought a new bar and replaced the chain. I go outside this morning thinking I'd figured it all out, and the same thing happened. Upon closer inspection, I noticed minor damage to the chain brake teeth on the handle end (see picture). I'm wondering if that is my issue or if I should consider locking nuts. Every time, the same thing occurred; one nut wiggled its way off and then the chain came off.

 

[Bob Hedgecutter]

At a guess- as the photos do not show the threaded section of the studs- the threads of one or both studs is damaged/partially stripped or cross threaded and the nut/nuts are no longer holding firm.
Running with loose stud nuts allow the clutch cover to jump out of mesh at the brake junction causing further damage.
In my opinion- for a Rancher grade saw like the 460, a 24 inch bar and chain is too much bar- you can put a lot of leverage on a powerhead with a stuck/pinched 24" and an angry operator.

 

[niefer]

At a guess- as the photos do not show the threaded section of the studs- the threads of one or both studs is damaged/partially stripped or cross threaded and the nut/nuts are no longer holding firm.
Running with loose stud nuts allow the clutch cover to jump out of mesh at the brake junction causing further damage.
In my opinion- for a Rancher grade saw like the 460, a 24 inch bar and chain is too much bar- you can put a lot of leverage on a powerhead with a stuck/pinched 24" and an angry operator.

Thanks for this, Bob. I've added a photo of the threads for context. I bought some nylon lock nuts and tension lock nuts to experiment, but it does make me a little nervous that it will just force something else to continue to go wrong. One thing I didn't do the last couple of times was to make sure that I had the bar oriented upward before tightening the nuts, so that could have contributed.