Anyone try repair stripped muffler threads - Husq 350

TradEddie · Apr 24, 2014

I've used and abused my Husqvarna 350 beyond anything it was ever designed for, and the only problem I've had was when I excessively tightened the muffler bolts on a hot cylinder, stripping the threads. I repaired it with helicoils, but the bolts do continue to vibrate loose, and eventually either the helicoils or the bolt threads get stripped again. I've run out of helicoils from repeated repairs so before I buy more, I was considering other options. I notice that there is a Husqvarna thread repair insert for exactly this job, has anyone else had experience using it?

TE

Giles · Apr 24, 2014

TradEddie said:
I've used and abused my Husqvarna 350 beyond anything it was ever designed for, and the only problem I've had was when I excessively tightened the muffler bolts on a hot cylinder, stripping the threads. I repaired it with helicoils, but the bolts do continue to vibrate loose, and eventually either the helicoils or the bolt threads get stripped again. I've run out of helicoils from repeated repairs so before I buy more, I was considering other options. I notice that there is a Husqvarna thread repair insert for exactly this job, has anyone else had experience using it?

TE

I haven't had any experience with Husqvarna thread repair, but I can assume it is quite similar to a helicoil repair.
With that being said, since you have already installed a helicoil, it may not work.

Jags · Apr 24, 2014

I can tell you a hillbilly way to keep the bolt from backing out - but will refrain unless requested.

yooperdave · Apr 24, 2014

Call your dealer and ask him if there is a chance of breathing a bit more life into it? They must've been down this road before.

TradEddie · Apr 25, 2014

Jags said:
I can tell you a hillbilly way to keep the bolt from backing out - but will refrain unless requested.

Requested...

TE

Jags · Apr 25, 2014

Repair with helicoil. Note how much of the bolt is going into the threads when muffler is tight. Take bolt back out and on the LAST (not the first) few threads, take a sharp chisel and ding the threads in ONE small area. As the bolt is almost tight, the last few threads act like an interference fit. Its hillbilly loctite. Don't over do it.

Razo · Apr 25, 2014

Jags said:
Repair with helicoil. Note how much of the bolt is going into the threads when muffler is tight. Take bolt back out and on the LAST (not the first) few threads, take a sharp chisel and ding the threads in ONE small area. As the bolt is almost tight, the last few threads act like an interference fit. Its hillbilly loctite. Don't over do it.

Nice! Almost like a staked nut, never thought to do it to a bolt.

pma1123 · Apr 25, 2014

On several other powersport applications that like to shake loose hardware, I've had good luck using nord-lock washers I bought at Fastenal.
They are "expensive" for washers, but have cured the issue of bolts that like to back out in extreme vibration environments.
The backing-out part isn't the issue, its the way a loose fastener galls-up the aluminum threads, or stainless helicoil inserts.
Nord locks hold the fastener tight under the head of the fastener, not by the threads.

smokedragon · Apr 29, 2014

Are you using high temp thread locker??

If not, there is your first problem.

I have also had good luck using JB WELD on the outside of the heli-coil and then thread locker on the bolt itself (though that is a bit more extreme, the heli-coil will NOT come back out if you do it that way).

Jags said:
Don't over do it

I love your idea Jags, but most people will overdo it

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Anyone try repair stripped muffler threads - Husq 350

TradEddie

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Giles

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Jags

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yooperdave

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TradEddie

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Jags

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Razo

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pma1123

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smokedragon

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