Flywheel removal made easy

[nmurph]

This is how I remove flywheels. I may get jumped for doing it this way, but I have removed many, many, (probably into the hundreds) and I have never had a problem with a FW or crank. I have a cousin who owns a mower and saw shop and he showed me this a couple of years ago. He said he has been shown this way at many training schools. He is in his early 80's, still sharp as a tack, and works his shop every day.

There are three points in doing it this way-

1) back the FW nut off until the crank stub is just below the top of the nut (one turn or so below flush).
2) grip the fin as shown over the magnets or the counter balance using just the outer end and avoiding putting pressure across the curved surface of the fin.
3) hold the saw up of the bench and give the nut a sharp whack with a hammer. Repeat if it doesn't pop off the first two or three times, making sure the nut doesn't turn and the stub stays below the nut. If it doesn't come loose, rotate the FW 180° and repeat.

I have only been defeated a couple of times using this method. Then it's time to break out the heat gun and PB Blaster!!

 

[Somesawguy]

Thanks for the tip. I'm always apprehensive about breaking off fins that way.

I've used a large screwdriver to pry up slightly on the flywheel, and given the nut a good whack when working on lawnmowers, and other small engines. It seems to work ok.

 

[gmax]

I use a similar method although lifting a Alpina 120 by the flywheel is easier with 2 pair of vice grips, they all pop off this way without any damage.

 

[nmurph]

Thanks for the tip. I'm always apprehensive about breaking off fins that way...

Hence the reason to grab them right at the end where they are relatively flat. I should have mentioned to grab them low to the magnet to reduce the leverage applied to the fin.

 

[FreeFlowin]

Question: To remove the clutch on the opposite side, do you put a vice grip on the fly wheel or do something to stop it from spinning when you try to break the nut on the clutch? I might be doing this soon for the first time, but don't want to break anything.

 

[struggle]

Question: To remove the clutch on the opposite side, do you put a vice grip on the fly wheel or do something to stop it from spinning when you try to break the nut on the clutch? I might be doing this soon for the first time, but don't want to break anything.

No don't do that you will break fins to try and spin a clutch off that way. Use a piston stop or use rope method in cylinder to remove a clutch.

 

[FreeFlowin]

No don't do that you will break fins to try and spin a clutch off that way. Use a piston stop or use rope method in cylinder to remove a clutch.

Excellent, thanks.

 

[nmurph]

Or use a torque wrench and let the compression of the motor do the work for you.

 

[Lakeside53]

You can do that on most short fat-taper flywheels, but if there is a threaded insert for flywheel removal it probably has a long taper so use/make the correct tool.

Chainsaws aren't mowers; they idle faster than most mowers run. I would never put a vice grip on a fin. If you crack it and it comes off at 14,000 rpm, duck fast.

 

[zogger]

I've always done lawnmowers that way, works good. Must be a back and forth shock wave happens for it to work.

 

[jockeydeuce]

I'm with Lakeside......The law of averages says you'll regret the hammer method at some point. I have bought and made pullers for pulling almost every saw flywheel I've worked on and never regretted it....I have however regretted the "short cut" method. Not saying I've never done it with success. Just that it sucks when it doesn't go as planned.:bang:

 

[nmurph]

You can do that on most short fat-taper flywheels, but if there is a threaded insert for flywheel removal it probably has a long taper so use/make the correct tool.

Chainsaws aren't mowers; they idle faster than most mowers run. I would never put a vice grip on a fin. If you crack it and it comes off at 14,000 rpm, duck fast.

Andy, can you ID the FW in the pic?

 

[Agrarian]

For chainsaws, I have only worked on Husky's. I back the flywheel nut off completely and give the shaft a quick spray of wd40. I then take a small hammer and lightly tap the fins (on the top thin edge) in a circular sequence. Pops it off every time, no fin damage and minimal effect on the magnets, bearings and seals. Just make sure when re-assembling that the shaft and flywheel are completely dry/clean - you want a good metal-to-metal bond there.

As for the nuts on either the flywheel or clutch, I use an air impact wrench but be very careful to get the direction correct when removing the clutch!

 

[sefh3]

You can do that on most short fat-taper flywheels, but if there is a threaded insert for flywheel removal it probably has a long taper so use/make the correct tool.

Chainsaws aren't mowers; they idle faster than most mowers run. I would never put a vice grip on a fin. If you crack it and it comes off at 14,000 rpm, duck fast.

I was working on an Stihl 025. I dropped the flywheel and it didn't look cracked or broken. I installed it on the saw. Rev'ed it up once and let it come back to an idle. I hit the throttle again and it blew into pieces. It destoyed the crankcase, cylinder, and coil. These things do explode and it's a worthless feeling.

 

[Chris-PA]

I've done it almost that way, except I hold the saw up by the flywheel with my hand, set a brass slug on the end of the nut and whack that with the hammer.

 

[pops21]

I do the same thing just a wee bit different. I hold a ball peen hammer on the fly wheel and use another hammer and wack the one that I am holding on the fly wheel. That way the hammer is taking the blow instead of the crank. Done it probably 20 times. Takes one or two wacks.

 

[redunshee]

Or use a torque wrench and let the compression of the motor do the work for you.

If the clutch has a nut attaching it to the crank, I always use a torque wrench. Works great. If the clutch is threaded on the crank I use a rope stuffed in the cylinder being sure the piston is above the intake and exaust ports.

 

[Jacob J.]

You can do that on most short fat-taper flywheels, but if there is a threaded insert for flywheel removal it probably has a long taper so use/make the correct tool.

Chainsaws aren't mowers; they idle faster than most mowers run. I would never put a vice grip on a fin. If you crack it and it comes off at 14,000 rpm, duck fast.

I'm with Lakeside......The law of averages says you'll regret the hammer method at some point. I have bought and made pullers for pulling almost every saw flywheel I've worked on and never regretted it....I have however regretted the "short cut" method. Not saying I've never done it with success. Just that it sucks when it doesn't go as planned.:bang:

I just hold the flywheel by hand, supporting the weight of the saw. That way you're not going to crack/break fins and you work on your bicep strength at the same time...

Welcome back Andy!

 

[jerrycmorrow]

many variations to this. mine is:
set nut as originally described, hold saw with flywheel facing down, strike nut sharply with 3# hammer, voila!
i'd be really afraid to even tap the cooling fins. no, or very little, flexural strength in those things. too easy to crack.
just sayin

 

[JDNicol]

I only use the "hammer" method when there is no other option. The flywheel in the pic looks like the "new" stihl type. 341/361?
The correct tool uses the two threaded holes either side of the flywheel nut. Part number 5910 890 4504 for;
241,261,271,291,311,391,341,361,362,441.

The hardest flywheel (on a chainsaw) I have ever had to get off was a stubborn one on a 070/090... with the right puller.