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Forget the piston stop
- Thread starter samaritan
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That is why I don't join groups- grumpy old loner means only one idiot to blame.
That is how I got for free a Stihl 361. Installed the flywheel without the key. Was given a new cylinder and piston, bought a few parts for it. Life is good and have a nice running chainsaw.
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Agreed I can only blame me for how my saws run. That is why I own and use my own chainsaws while the group battles over group saws and complain about how the last person left the condition of the saws.
Stinks though when the guy in the mirror is the guy to blame......... been there many times.That is why I don't join groups- grumpy old loner means only one idiot to blame.
I still have a tractor down because some impatient arse..... rolled through a pasture with the sun in his eyes. That same guy took out a $1000 windshield for the exact same reason in the same pasture. Dipstick ( me)
I snapped a crank once with a impact I did fix it though
It is becoming more popular with the increased torque some of these battery guns put out. I have a 3/4 and heck they have Milwaukee 1' that can run i believe around 1400lbs. Of course no one would use that on a saw but heck the 1/2 put out the torque of my 3/4..
Chaps I respect the choice you make in using them, but I prefer to use some soft cotton 8mm rope well placed into the combustion chamber and ensuring that the piston is above the exhaust port so there is no issue catching a port with the rope.
The Shooters Apprentice
Addicted to ArboristSite
I broke a scrench trying to get a clutch loose on a Jonsered 670 a couple weeks ago trying to get the clutch busted loose. Hit it was a 3/8” impact and came right off.
Dennisthemenace
ArboristSite Operative
Never had any trouble using a 18 v Dewalt rattle gun to remove clutches, or carefully removing flywheel nuts. No stop required.
I usually use a plastic piston stop when torquing the nut back down, by hand of course. It's only 25 ft/lbs so not enough pressure to hurt the rod or piston etc.
The chain brake tightens the clutch.
I usually use a plastic piston stop when torquing the nut back down, by hand of course. It's only 25 ft/lbs so not enough pressure to hurt the rod or piston etc.
The chain brake tightens the clutch.
I wonder now more about the science of impact.
Thinkin' out loud...with a piston stop and wrench with torque slowly and gently applied and increased, the torque applied to the nut is transferred through all the parts all the way to the piston stop. They are likely not excessive under normal circumstances. When the nut breaks free, the forces go to zero on all the parts like the crank and piston and connecting rod and wristpin, etc. Duh.
With the impact, a jolt is applied to the nut. The flywheel has significant mass and rotational inertia, as does the crank, significantly more than the nut. The lobes on the crank, and the flywheel itself, are there for rotational inertia. A quick force spike to the nut breaks the nut free before the flywheel and crank can begin to rotate. Because of their inertia, from the crank and flywheel's perspective, barely anything happened before the nut flew off. Near zero forces and torques are therefore applied through the piston, con rod, and wristpin, etc., assuming the nut breaks free relatively easily.
In the case where the flywheel is held still, even less is transferred to the other parts, but I guess one could break a flywheel fan blade that way. However, the radius from the outside of the flywheel to the crank center may be, say, 3 inches while the radius between nut threads and crank is say, 0.25 inches, Since the outside of the flywheel is further away, for a given torque, it takes less force to hold it in place against the nut torque. The fan blade is unlikely to break, especially if multiple blades are held with a rag, etc.
With the impact, a jolt is applied. We really don't know how hard that jolt is, which is probably the biggest risk. A jolt in the wrong direction may be even worse. Application of steady torque with a wrench can be easily measured.
I like impact.
Witchcraft?
Thinkin' out loud...with a piston stop and wrench with torque slowly and gently applied and increased, the torque applied to the nut is transferred through all the parts all the way to the piston stop. They are likely not excessive under normal circumstances. When the nut breaks free, the forces go to zero on all the parts like the crank and piston and connecting rod and wristpin, etc. Duh.
With the impact, a jolt is applied to the nut. The flywheel has significant mass and rotational inertia, as does the crank, significantly more than the nut. The lobes on the crank, and the flywheel itself, are there for rotational inertia. A quick force spike to the nut breaks the nut free before the flywheel and crank can begin to rotate. Because of their inertia, from the crank and flywheel's perspective, barely anything happened before the nut flew off. Near zero forces and torques are therefore applied through the piston, con rod, and wristpin, etc., assuming the nut breaks free relatively easily.
In the case where the flywheel is held still, even less is transferred to the other parts, but I guess one could break a flywheel fan blade that way. However, the radius from the outside of the flywheel to the crank center may be, say, 3 inches while the radius between nut threads and crank is say, 0.25 inches, Since the outside of the flywheel is further away, for a given torque, it takes less force to hold it in place against the nut torque. The fan blade is unlikely to break, especially if multiple blades are held with a rag, etc.
With the impact, a jolt is applied. We really don't know how hard that jolt is, which is probably the biggest risk. A jolt in the wrong direction may be even worse. Application of steady torque with a wrench can be easily measured.
I like impact.
Witchcraft?
I learned the best method (for myself) and I'll share it with you.That is how I got for free a Stihl 361. Installed the flywheel without the key. Was given a new cylinder and piston, bought a few parts for it. Life is good and have a nice running chainsaw.
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Agreed I can only blame me for how my saws run. That is why I own and use my own chainsaws while the group battles over group saws and complain about how the last person left the condition of the saws.
Any time I remove a flywheel I use a fine tip auto center punch to put a divot on the flywheel lined up with the key then mark the divot with a red paint pen. I do the same to the crank end so I have base timing marks for quick accurate reassembly and later at a glance the key can be checked without removal of the flywheel. One could also use this method to make timing marks on the outside edge of the flywheel and case to be used as timing light marks using a degree wheel to set your own base timing.
Buying used saws and saw parts you will eventually get one with the key missing, sheered or ground down by others.
samaritan
ArboristSite Operative
Well, I see opinions on both sides, I don't regularly work on saws, just mine occasionally, so I'll do whats easiest, until I break something
@cookies That is very good advice! The sheared flywheel 361 I did punch guide marks to show where the key would be. Cleaned up matting surfaces very well, touqed the nut down and have not thought about it.
I have used a 1/4" impact to remove clutches for years with no piston stop of any kind and without holding the flywheel. Never had an issue...
I thinking some of you guys are ham fist mechanics.
I thinking some of you guys are ham fist mechanics.
I probably do 2 or 3 a week. Vast majority breaking the fan off of a blower or the flywheel nut off of same, chainsaw clutch not so much. Replaced a straight gassed motor in a BR600 this morning.
Only problem I have ever had is punching a hole through the top of a piston on a MS170 .
One out of who knows how many. Sometimes I use a rope, sometimes the stops that screw in the plug hole, and sometimes those plastic whatyamycallits that go in the plug holes.
Doesn't seem to be an issue one way or the other.
I think some of you could tear up most anything.
Only problem I have ever had is punching a hole through the top of a piston on a MS170 .
One out of who knows how many. Sometimes I use a rope, sometimes the stops that screw in the plug hole, and sometimes those plastic whatyamycallits that go in the plug holes.
Doesn't seem to be an issue one way or the other.
I think some of you could tear up most anything.
I've never used a flywheel puller either. Back the nut out a bit and give it a tap with a hammer. Pops right off.
Yeah, but you got to get the nut loose.
Luckily most new stuff has a nut with a skirt so you can just use a socket, old stuff without a skirt a little hard to do by yourself.
Luckily most new stuff has a nut with a skirt so you can just use a socket, old stuff without a skirt a little hard to do by yourself.
Not chainsaw related but when I was in automotive school a classmate was trying to remove the crankshaft pulley on small block chevy lab engine. He turned the huge bolt clockwise and broke it off in the crank. The instructor was more than po'd. I think he flunked the kid.
1/4" impact.
I use a little impact as well. Haven't ever had an issue using that method.
And you won't if you use your head a little bit..Some of these guys could break a anvil.
