Husky 450 With Loosenin Bar Nuts

[apn73]

Hello All,
My wife's grandfather has a Husqvarna 450 that he's owned now for 10 years and it's treated him pretty well until recently. It's got the classic 2 stud and nut bar and chain tensioning set-up, but all of the sudden the nuts are vibrating loose while he's operating the saw, and the bar will fall right off of the thing. Have any of you experience this with the Husky 450's? Do you what causes it and how to fix it?
Thanks,
Adam.

 

[ChillyB]

Are the studs pulling out of the case?

 

[apn73]

Are the studs pulling out of the case?

No, they appear to just be back off the threads.

 

[cscltd]

Missing flywheel fins?
I have seen bar nuts come loose if saw running too lean and over speeding cause harmonic imbalance

 

[Bearcat22lr]

Are they captured? Try replacing them.

 

[apn73]

Missing flywheel fins?
I have seen bar nuts come loose if saw running too lean and over speeding cause harmonic imbalance

I had wondered if the antivibe isolators have bitten the dust.

 

[SawTrash]

He probably has been overtightening for those years and worn the threads on the studs and nuts, in which case new nuts will not be a proper fix.

Or maybe simply not tightening them enough.

Very dangerous if the bar is coming loose while cutting.

 

[Tomos770]

They can be replaced....depends in what condition is plastic around them! Page 52

 

[Old2stroke]

My bet would be worn or partially stripped threads on studs or nuts or both. Try lockwashers under the bar nuts.

 

[scottr]

Over revving due to high rakers can cause screws and nuts to loosen .
Do the bar nuts have a little drag if you thread them on with your fingers ?

 

[apn73]

....Very dangerous if the bar is coming loose while cutting.

That's for sure. Thanks for the advice, I'll tell him replace both the studs and the nuts, and tell to not go crazy on the torque, or put more beef on it. I would bet it's not tight enough, he is 86 years old!