Jonsered 455; really, this little tiny free floating sprocket is all that drives the chain?

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Dune

Minister of Fire
Seems pretty wimpy for all the work it does.
 
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$(KGrHqMOKjUE4fH!HF(WBOSCJW)G0Q~~0_3.jpg
Seems pretty wimpy for all the work it does.
It could use a solid sprocket like this
 
I prefer the rim sprocket, but it requires more care when replacing the chain. When you put a chain on it's possible to miss the rim and when you go to pull start the saw- it'll feel like the bearings are locking up. I think the rim sprockets last longer and allow more consistant chain tensioning. The engine's crankshaft drives the centrifugal clutch, which drives the sprocket, which drives the chain.
 
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I prefer the rim sprocket, but it requires more care when replacing the chain. When you put a chain on it's possible to miss the rim and when you go to pull start the saw- it'll feel like the bearings are locking up. I think the rim sprockets last longer and allow more consistant chain tensioning. The engine's crankshaft drives the centrifugal clutch, which drives the sprocket, which drives the chain.

Mine looks like that but it has a LOT of sideplay, like .1875" per side.
 
My rim sprocket has stood up for more than 30 years.
 
That side play makes it easier to get the bar and chain on and off. Like MasterMech said it is self aligning once assembled. If the side play weren't there it would be a pita to use.
 
That side play makes it easier to get the bar and chain on and off. Like MasterMech said it is self aligning once assembled. If the side play weren't there it would be a pita to use.
The side play has to be there. When you mount a bar the wood and oil residue may shim it out a little. If the sprocket didn't float the chain would never be in perfect alignment with the bar.
 
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If you can see marks on the tie-straps (shiny spots) of the chain, your rim sprocket is long past it's expiration date.
 
If you can see marks on the tie-straps (shiny spots) of the chain, your rim sprocket is long past it's expiration date.

Are they expensive? I like this saw, and am inclined to replace it if they are reasonable. OTOH, I paid $80 for the saw years ago, it has cut plenty of wood, but it still runs good and cuts fast. Thanks for the input.
 
Rims are 4 or 5$ at Baileys, just change them out every couple chains.....
You can also try 7 or 8 teeth and see which works best.


that .188 on both sides: Do you mean total back and forth motion of 3/8 inch?
something is not right. it should be much less, maybe 1/8 inch total motion.. Is there a snap ring and a washer holding the rim and clutch hub on?
 
Rims are 4 or 5$ at Baileys, just change them out every couple chains.....
You can also try 7 or 8 teeth and see which works best.


that .188 on both sides: Do you mean total back and forth motion of 3/8 inch?
something is not right. it should be much less, maybe 1/8 inch total motion.. Is there a snap ring and a washer holding the rim and clutch hub on?

Yes, fully 3/8" side play. I will be bring it to the repair shop for visual inspection by the mechanic. Thanks for the input, I didn't think it looked right.
 
3/8" side play is possible and on the upper end of what I would like, but if it is working fine don't worry about it. Like wkpoor said it is self aligning. It may be possible that you have a clutch cover from one manufacturer and a sprocket from another. The stub on the sprocket could be a little longer than what the sprocket was set up for. As long as it cuts OK I would leave it alone.
 
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