I noticed my sprocket was very hot after a session and took everything apart. This is what I found: Okay this looks bad to me, but I know nothing about chainsaws. I cleaned up the clutch: If I didn't know any better, I'd say all the friction material is GONE. However, when I look at a clutch for sale online: Another sample: Well hell. There is no friction material. So how do these clutches work? How do I know if I have a clutch worn past spec or not? I usually clean my saw with WD40 so I suppose it's possible what I thought was "friction material" might just be accumulated WD40 and sawdust. Is there a way I can measure this thing for proper tolerances, or what do I do?
Basically the weight of those “shoes” make them want to fly off and they make contact with the drum to engage drive. Yours looks fine to me but.. there shouldn’t be all that black material in there? It should be dry, not a good place for any lubricant like WD or grease. Only place for a bit of grease is the bearing that sits between the drum and crankshaft. Use only compressed air to clean that area out.
Yes I am familiar with the basics of a centrifugal clutch, however my experience with them is with motor scooters and those do in fact have friction material. So I'm kinda baffled. I'm also baffled by the needle bearing which looks totally dumb from an engineering standpoint. Do the pro saws have the same design?
Okay, after doing some more light reading online, it sounds like chainsaw clutches are all metal and don't (seem) to have a failure mode where the contact surfaces wear down, in general. One post on arboristsite mentioned a wear indicator which would be good to know where that is. I think my takeaway is my clutch is fine. I'll wait for some other folks to chime in though.
Typical for the drum to wear thin, not the shoes. Needle bearing is only being used (so to speak) while at idle. When clutch is engaged, drum is turning w crank 1/1. Your lubricant caused a bit of slip, generated heat and made things black. At least that’s what I see.
Of course I can't do anything right, managed to somehow shear the key off the flywheel either during assembly or disassembly. Probably did it while I was discovering the clutch is reverse threaded. New one on the way. Hopefully the reason they make the flywheel out of pot metal is to avoid damaging the crank, and that's all it needs to get going again. Good times. I'm one more incident away from buying an Echo. I can't point the finger at Stihl for this muck up but the parts availability issue just continues to be a constant thorn in my side. Annoyingly my M18 saw is at Milwaukee for service so I have zero operational saws right now. I'm one downed tree from being trapped at my house. Second time this spring that both saws have been out of commission at the same time. I'm taking the next incident as a omen that I really need to own 3 saws rather than two.
Did you use a piston stop or put a piece of rope in the plug hole so stop rotation before taking off the clutch? It sounds like you held the flywheel somehow and that sheared off the key.
If find it ironic that there’s a fresh thread about this. Because I just broke a weight on the clutch of my 562 around 6pm today. And yes I was going the proper direction, just got the punch set in the wrong spot before a really good whack.
Looking at the crank key it's easy to see how these break. Just a tiny 1mm or so of pot metal is all that's keeping it in place. Shoulda been designed with a friction taper fit and this whole thing could be avoided. Oh well. Got the new flywheel in, as well as the rim sprocket and drum so I went ahead and installed those. Went without a hitch except it is an absolute bear to get the drum off the needle bearing. Even though it had been recently re-greased and reinstalled, it's an interference fit and is extremely tight. I was using channel locks to work the drum loose and I kept slipping and busting my fingers. By the end of it I was cussing up a storm and throwing tools. Anyone have tips for next time?
The taper IS what holds the flywheel in place once tightened. The key is only to get it lined up correctly for ignition timing. They generally don't get sheard off unless someone did something to cause it or somehow the nut came loose. I had a Husqvarna trimmer I fixed that the nut came loose from the flywheel and sheared the cast in key. I lined it up in the correct position, tightened it down and it the owner has had no more issues. The drum bearing should slip in and out with ease. You didn't have the break on did you?
Nope. no idea why its just a tight fit. very annoying though. saw works fine. That nut holding the flywheel must have come loose when I was removing the clutch, as I didn't touch it until I noticed a problem. Interesting to know about the design. I suppose I could have lined things up carefully and kept my existing flywheel. Oh well.
It's best to use a plastic piston stop or rope through the plug hole to stop the piston before removing the clutch or flywheel. As far as your drum bearing, that's not normal. They usually fall out when you remove the drum unless grease keeps them in the drum.
