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Sthil MS 180 repair question

bsdubois

bsdubois

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Does anyone know the correct torque value (Nm/inch pounds etc) for the flywheel nut on the Stihl MS-180? I made some major mistakes (my Dad used to say costly learning) with this saw. I decided to disassemble it to replace the oil line on the bottom of the saw (no shop manual and I did not find this forum until now). First dumbass move. I purchased the Stihl cylinder stop (special tool) for my Dad's 030, 020 and my 015 years ago. I used it on the Ms180 and bent the top of the soda can thin piston and left a small hole in the top of the damn piston. The saw set unassembled for about 2 or 3 years. I found on OEM piston on eBay, purchased it and reassembled the saw. I found 99% of the parts and purchased the missing part for less than $10.00 at my local dealer. I thought I had the nut tightened enough on the flywheel. I started the saw several times and it ran better than new. The last time I stopped the saw I hear the sickening sound of the flywheel breaking loose. It wiped out the chicken **** cast aluminum key. I suppose it would have cost Stihl too much to have cut a keyway in the flywheel and inserted a small, replaceable, key. I know you can'/t fix stupidity... and, at 60+, I should know better than to pull a stupid move.

Final questions: Is it ok to attempt to hold the flywheel with a rubber strap wrench while I torque the nut to the proper value? I know better than to use the spark plug stop that was designed when Stihl actually made decently built saws and not the plastic junk they currently sell. I don't want to use the rope in the cylinder technique after seeing photos of bent connecting rods. I don't want to use an impact because of the warning mentioned by various Stihl dealers/users on this forum. My goal is to reassemble the saw without any further stupid mistakes.

Please overlook the length of my first post. I will attempt to be more succinct in the future (assuming you don't kick me off for my first post). I hope I posted this to the correct thread. Please move and advise if I made a mistake.

Thank you for allowing me to join this group. I look forward to your replies and suggestions.

Sincerely,

Brían S. Du Bois
Evansville, IN
 
rupedoggy

rupedoggy

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Clean off all the oil/grease from the flywheel hole and the crankshaft. Be sure there is no scratches/burrs in there. Line up the flywheel where is was when it had a key. Tap it a little with a socket that fits over the crank. Now tighten the nut. Use your strap wrench if you want but be sure it is where it needs to be for ignition timing. Good and tight on the nut and go to cutting. The taper holds the flywheel not the key. Mike
 
HarleyT

HarleyT

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I do agree on not listening to a lot of the guys here on this though.
But yeah, line that old flywheel up where it is supposed to sit, Smurf it down tight with an impact.
Of course, common sense should be employed when doing things.
 
TheTone

TheTone

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As above, the flywheel key is little more than a marker for the stock timing. No loss. Just be sure the flywheel and crankshaft mating surfaces are SQUEAKY CLEAN of all oil and grease. The taper and torque keep the flywheel from shifting. Torque it right and thereafter the inertia of running the saw should keep it tight
 
ChoppyChoppy

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A trick I learned on this site, use toothpaste on the shaft and then line up the flywheel. The grit will hold fast on the shaft with a good tightening.:cool:
No, it's a tapered shaft. A clean surface is what is needed. Douche it with brake clean and blow it out if need be.
Set the flywheel down, tappy tap tap with a hammer if needed, crank the nut down.
The key is just a reference for installing the flywheel and nothing more. Plenty of tapered shafts that are held just by the taper.
 
grizz55chev

grizz55chev

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No, it's a tapered shaft. A clean surface is what is needed. Douche it with brake clean and blow it out if need be.
Set the flywheel down, tappy tap tap with a hammer if needed, crank the nut down.
The key is just a reference for installing the flywheel and nothing more. Plenty of tapered shafts that are held just by the taper.
Using toothpaste is a trick taken from motocross mechanics.

Tootpaste dries to a glue like substance and the grit adds surface area and holding ability. The bond continues to allow easy fly wheel removal.


I had a 262XP that had a sheared keyway and would not hold time. I dabbed toothpaste, set the timing, and tightened the nut with blue loctite. Been running 4 years, no keyway, timing has stayed constant.

I have used it on a few 394XP's to.

Using toothpaste as a search word I found another thread discussing this technique.
http://www.arboristsite.com/chainsaw/98002.htm
 

CJH

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Collegeville, PA
plenty of tapered shafts that are held just by the taper.
Tapered shaft couplings are common in industry .Very high horsepower motors use tapered couplings, no keys. Hub is dialated with hydraulic pressure and pushed up the taper, held on with a surprisingly small nut.

Biggest one I work with is a 35,000 HP compressor. 100% contact on the taper is critical, blue the shaft and check contact. Lap it in for 100%
 
smokey7

smokey7

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Tapered shaft couplings are common in industry .Very high horsepower motors use tapered couplings, no keys. Hub is dialated with hydraulic pressure and pushed up the taper, held on with a surprisingly small nut.

Biggest one I work with is a 35,000 HP compressor. 100% contact on the taper is critical, blue the shaft and check contact. Lap it in for 100%
Holy hell 35000 hp wow thats alot.
 
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