Tightening flywheel nut on Stihl ms170

[Dacha]

Hello,

Replaced filters, spark plug, cleaned carb, put everthing back together and tested it succesfuly. All with no prior similar experience. This work 've done last week.

Than i replaced sprocket as old was a bit worn.

Decided to take my diy a step further as saw was leaking oil. Bought oil line.

Took handle off, pulled the old line out, replaced, but couldn't slide pickup body into place.

So took flywheel out (impact driver), in order to remove the oil tank, fitted the line, put tank back. Put flywheel back.

Tightened nut on flywheel as much as i could. Then i added 3 sligtht impacts with impact driver.

Should i worry if my flywheel is tightened close enough to spec ?

(I wasn't comfortable enough with puting rope into piston cylinder procedure) i felt i can mess up less w slight touch of impact.

Tested for oil leak, no more oil leak at present.

 

[Old2stroke]

Hello,

Replaced filters, spark plug, cleaned carb, put everthing back together and tested it succesfuly. All with no prior similar experience. This work 've done last week.

Than i replaced sprocket as old was a bit worn.

Decided to take my diy a step further as saw was leaking oil. Bought oil line.

Took handle off, pulled the old line out, replaced, but couldn't slide pickup body into place.

So took flywheel out (impact driver), in order to remove the oil tank, fitted the line, put tank back. Put flywheel back.

Tightened nut on flywheel as much as i could. Then i added 3 sligtht impacts with impact driver.

Should i worry if my flywheel is tightened close enough to spec ?

(I wasn't comfortable enough with puting rope into piston cylinder procedure) i felt i can mess up less w slight touch of impact.

Tested for oil leak, no more oil leak at present.

Should never tighten anything with an impact driver, they're only for taking things off. Only way to be sure if it's the right tightness is to use a torque wrench. Nothing wrong with using rope as a piston stop as long as the piston is above the exhaust port so that the rope doesn't get caught in the port.

 

[irhunter]

Then i added 3 sligtht impacts with impact driver.

Should i worry if my flywheel is tightened close enough to spec ?

(I wasn't comfortable enough with puting rope into piston cylinder procedure)

You made sure everything was clean, dry, oil-free before putting flywheel on?

You really should either come to terms with the rope method or buy a piston stop. There are not a lot of bolts/nuts on a saw which require a torque wrench...but, the flywheel is one of them.

FWIW, I like 5-6 mm diameter nylon rope.

Roy

 

[irhunter]

BTW,

Regarding your MS170 in general, have you read the KostasVolos post?

https://www.arboristsite.com/threads/stihl-ms180-upgrades.365661/

Roy

 

[earlthegoat2]

For my own saws and equipment I just use the impact at my own risk. For customer saws and the equipment at my work I retighten with hand tools and torque tools.

I think your flywheel is fine as you tightened it with you impact the same way I do.

I use a low torque 1/4” hex impact driver.

 

[Dacha]

I used a 1/4” hex impact driver as well.

I applied just a little, 3 knocks, after tightening it by hand as hard as i could without blocking piston.

 

[Dacha]

Anyone have idea if undertorqued nut can loosen, causing flywheel to come off or fly off the crankshaft ?

I mean at 9000 rpm speed, it has a lot of energy, enclosed only by plastic cover.

If it loosens and sits in place, loss of power will happen. Which would tell you stop. Tighten the nut.

 

[pioneerguy600]

Anyone have idea if undertorqued nut can loosen, causing flywheel to come off or fly off the crankshaft ?

I mean at 9000 rpm speed, it has a lot of energy, enclosed only by plastic cover.

If it loosens and sits in place, loss of power will happen. Which would tell you stop. Tighten the nut.

The saw will stop long before the nut will thread all the way off, as soon as the nut becomes even a little bit loose the key will shear off and the saw will stop. That is why a flywheel nut is left hand thread, it is a self retaining feature.

 

[Dacha]

Thank you very much on this info.

Don't remember the nut being left hand threaded though.

Maybe bigger saws have left thread. This one had right thread. I could double check.

 

[pioneerguy600]

Thank you very much on this info.

Don't remember the nut being left hand threaded though.

Flywheel nuts are most commonly left hand thread. Lets say a saw did have a right hand thread nut ,then the same scenario would be true, as soon as that flywheel even slightly loosens the key will shear and the saw stops. I have had running saws in my hands when the key shears, the engine compression stops the saws rotation very quickly, just like shutting off the switch does.

 

[montana59]

Flywheel nuts are most commonly left hand thread. Lets say a saw did have a right hand thread nut ,then the same scenario would be true, as soon as that flywheel even slightly loosens the key will shear and the saw stops. I have had running saws in my hands when the key shears, the engine compression stops the saws rotation very quickly, just like shutting off the switch does.

Not saying there are not, but I have never seen a left threaded fly wheel nut, on the clutch side yes

 

[Mad Professor]

The saw will stop long before the nut will thread all the way off, as soon as the nut becomes even a little bit loose the key will shear off and the saw will stop. That is why a flywheel nut is left hand thread, it is a self retaining feature.

@pioneerguy600 , have another coffee.

You're still dreaming about clutches..........

 

[GMB74]

Flywheel nuts = right hand thread
Clutch nuts/hubs/spiders = left hand thread

 

[pioneerguy600]

Yes ,you fellas are correct on the Stihls they are right hand thread. I was working on a Pioneer 600 last evening and it has left on the flywheel side,carry over from last endeavor. Corrected for posterity.

 

[pioneerguy600]

@pioneerguy600 , have another coffee.

You're still dreaming about clutches..........

It was a bit early for me and I had not even had my breakfast or my first cup yet, takes a while for my dyslexia to fade into the background. I have never removed a flywheel.

 

[Mad Professor]

It was a bit early for me and I had not even had my breakfast or my first cup yet, takes a while for my dyslexia to fade into the background. I have never removed a flywheel.

I usually have a pint of coffee before breakfast..........

 

[pioneerguy600]

I usually have a pint of coffee before breakfast..........

I did not sleep last night,was restless and my wife is very sick. Was up with her full time making hot drinks, buttered toast and getting her meds when needed, sort of throws me off a bit when I miss my sleep. It did help somewhat after eating my bacon and eggs and two cups of hot Joe. Then fired up the diesel and went over to the woodland,dropped 4 nice sized rock maple trees, limned, blocked, loaded and delivered to the woodyard. It will be next seasons wood, temp today hit one above freezing with a light NW wind, they say the wind chill feels like -10 but I hardly noticed it.

 

[Bob Hedgecutter]

It was a bit early for me and I had not even had my breakfast or my first cup yet, takes a while for my dyslexia to fade into the background. I have never removed a flywheel.

You were just using the old timers trick to see if everyone else was awake and willing to challenge age and experience.

 

[pioneerguy600]

You were just using the old timers trick to see if everyone else was awake and willing to challenge age and experience.

The age thing is steadily creeping up on me ,Bob. Parkinson may catch up to me yet.