Tightening Bar Nuts ~ How tight?

[PA Plumber]

Been wondering about this.
Neighbor has a Stihl 250 and the bar cover looks to be smashed under each bar nut. Hmmm.
Shorter bars I generally have a little less snug and longer bars put a little more into it.

Is there a need to get a cheater bar out to really get'm squeaky tight?

 

[Wonkydonkey]

You can get more than enough leverage with a scrench, after a while the mag casing shows the wear..

edit,, after losing a nut or they come lose, you know to nip them up a bit more. The thing is if the saws cold they need more of a nip. If it hot then less of a nip. metal expands .. you know when the saw is cold and they are really hard to undo..

you just figure it out Or it cost you money.

 

[PA Plumber]

Here's a cover off a 441.
My main firewood and felling saw since purchased new in Feb. of 2007.
There is a little wear starting under each bar nut.
Too tight?

 

[ammoaddict]

I just snug them up pretty good with the scrench. Never had one come loose and never damaged a clutch cover.

Sent from my moto g(7) power using Tapatalk

 

[Dub11]

3 ugga duggas will do it.

 

[kingOFgEEEks]

3 ugga duggas will do it.

Best Answer.

 

[PA Plumber]

3 ugga duggas will do it.

Is that about a 1/4 to 1/3 of the GNT scale?

 

[Dub11]

Is that about a 1/4 to 1/3 of the GNT scale?

1/4 with lube
1/3 dry

 

[Philbert]

I checked the service and owner manuals for several models of STIHL saws. There are tables for torquing screws that thread into plastic (polymer) and magnesium parts, but the directions for bar nuts all say 'firmly' - no torque specs given.

That said . . . .

Many years ago I was cautioned about 'over-tightening' these nuts to the point where the scrench would bend. I rolled my eyes to myself. Not long after I was servicing an MS250 that belonged to a camp I used to work at. When I went to remove the bar nuts, the scrench curled up like a wet noodle, into a spiral shape! Was told that they lost their scrench and were using a socket and ratchet to tighten the guide bar nuts.

Since then I have heard from many folks how easy it is to over-tighten these nuts with a ratchet. Could damage the plastic housings or metal cases. Not obvious why, unless they provide greater leverage?

Philbert

 

[PA Plumber]

I do like them snug (using a scrench)...Especially for 24" and up bars.
Just wondered how much wear/no wear I should be getting on a mag clutch cover?
That cover has been off and on at least hundreds of times.
Is the clutch cover considered a wear item?

 

[Stump Shot]

I've had to loosen some up with a two foot cheater pipe. At least the ones that didn't pull the studs through. Then was asked what caused that to happen.

 

[USMC615]

I've had to loosen some up with a two foot cheater pipe. At least the ones that didn't pull the studs through. Then was asked what caused that to happen.

200 ft/lbs...

 

[Stump Shot]

200 ft/lbs...

Probably more than that to rip one through the crankcase. Lol

 

[huskyboy]

I do like them snug (using a scrench)...Especially for 24" and up bars.
Just wondered how much wear/no wear I should be getting on a mag clutch cover?
That cover has been off and on at least hundreds of times.
Is the clutch cover considered a wear item?

Normal to wear. Too tight on bar nuts = bad... you can strip them or pull the studs. Too loose on bar nuts = bad... you risk breaking the chain tensioner when the saw kicks back or bore cutting.

 

[jk14]

Considering that most bar nuts are 8mm. the general torque should be roughly 20ft. lb. Which is just good and snug with a squrench, no need to really hammer on them too much.

 

[PA Plumber]

This just about right??

 

[Backtroller]

Yes but you need to set the saw upright and stand in the cheater bar for that extra torque

 

[TreeLife]

Normal to wear. Too tight on bar nuts = bad... you can strip them or pull the studs. Too loose on bar nuts = bad... you risk breaking the chain tensioner when the saw kicks back or bore cutting.

Especially with a 394/5

 

[WillG]

Two grunts of tightness.

Sent from my E6910 using Tapatalk

 

[Ryan Browne]

Especially with a 394/5

Already!?

Happened to me on like my third tank through my 395.