Clutch Drum Sprocket Wear

[hydestone]

Hi Guys,

Is it normal for a clutch drum sprocket to wear and form a groove after only 100 hours of use? Last week I kept throwing my chain off while cutting so I looked at the sprocket and noticed 2 grooves with a slight ridge in the middle. It seems as though this would be causing the problem of my chain coming off. Any ideas?

 

[MALogger]

Hi Hydestone,

The general rule of thumb is after you go through 2 chains you should change the sprocket. I just check mine when I have the side cover off for cleaning or changing chains and when it starts showing wear I replace it. A worn sprocket will definitely cause your chain to come off!

Craig

 

[Roospike]

The gear sprocket will need changed more often than the ring style. MALogger has it right to changing the sprocket with chain use . Helpful note : Dont let your chain on your bar get loose , keep it tight as it should , a loose chain will ware the bar and sprocket real quick or at least quicker tha it should. Throwing your chain is not very safe at all . Get your parts on your chainsaw fix ASAP .

 

[hydestone]

It looks like I will need to change the whole clutch drum assembly to change the sprocket. It looks like it is all one piece. Also, it seems as though I need a special tool to remove it. I am cutting with a Poulan 2375.

Can I just replace the sprocket or do I need to change the whole clutch drum assembly. Know any good websites for replacement chainsaw parts?

 

[MALogger]

Hi Hydestone,

To change that if it is an inboard spur which it probably is, you need to take the assembly off but the clutch shouldn't need to be replaced. You need a way to stop the piston form moving up an down ironically the tool is called a piston stop then then you turn the nut on the clutch clockwise to loosen (at least that is how it is on my oldhusqvarna) then take the clutch out from the inside. The outer part has the spur on it.

If you don't have a piston stop you can take the spark plug out and look in the cylinder ans slowly pull the cord until the piston is down (away from the spark plug hole) then take some clothesline and simply fill the cylinder with out. Make sure you leave plenty hanging out so you can get it back out.

If you aren't comfortable doing that it is a shop job or a buddy who can do it.

(broken link removed)

Not sure if that will fit you model but you could call bailey's or where you bought the saw.

Hope that helps!

Craig

 

[Eric Johnson]

If you take it to a dealer, they'll probably use an airwrench to get it off. The wrench turns fast enough to get ahead of the piston. I don't think you can use a piston stop if the spark plug hole enters the cylinder head anywhere but directly above the piston. Any slant or angle and they say you shouldn't use one.

I've never heard the clothesline idea, Craig, but that's a great tip.

In my experience, the spur sprockets show a fair amount of wear before they need replacement. The way to tell for sure if it's worn out is to turn your chain around the bar by hand. If the chain rises and falls as you turn it (i.e., it's tight in one position and loose in another), then it's time for a new sprocket. If the tension stays pretty steady, on the other hand, then your chain problems are probably being caused by something else.

 

[BrotherBart]

Wow old dog learning a lot of new tricks today. Thanks MA for the clothes line tip and Eric for a way to check a sprocket.

Woof!

 

[slofr8]

We used to just put the big end of our bar wrench on the nut holding the clutch at the 10 oclock position and give it a sharp hit with the tip of the bar. 9 times out of 10 the nut would spin right off with out even taking the plug out. Did this many times on the tail gate of a pick up.
Dan.

 

[Roospike]

If you don't have a piston stop you can take the spark plug out and look in the cylinder ans slowly pull the cord until the piston is down (away from the spark plug hole) then take some clothesline and simply fill the cylinder with out. Make sure you leave plenty hanging out so you can get it back out.


Craig

I do the same thing except i use the starter rope on the chainsaw to stick in the hole. You can take it to most chainsaw service centers and it should only cost about $10. $15. for a new one installed. You can have them replace your fuel filter, tune your carb and set your RPMs wile your at it.

 

[Eric Johnson]

^^That's the best advice.

 

[Eric Johnson]

I like slofr8's idea, too. I think that would work pretty well.

One word of caution: NEVER run the saw without the bar and chain. Chain saws are designed to reach high RPMs with all the gear attached. If you try to run the saw at high RPM without that drag, you'll exceed the specs of some of the components (most notably, the clutch drum) and they can (and do) disintegrate, sending shrapnel all over the place.

Also, as soon as your saw sounds like it's running out of gas, shut it off. If you try to keep going and get every last fume out of the tank, you risk damaging or destrotying the engine due to it running lean. There's no oil in fumes.

 

[Sandor]

If you take it to a dealer, they'll probably use an airwrench to get it off. The wrench turns fast enough to get ahead of the piston. I don't think you can use a piston stop if the spark plug hole enters the cylinder head anywhere but directly above the piston. Any slant or angle and they say you shouldn't use one.

I've never heard the clothesline idea, Craig, but that's a great tip.

In my experience, the spur sprockets show a fair amount of wear before they need replacement. The way to tell for sure if it's worn out is to turn your chain around the bar by hand. If the chain rises and falls as you turn it (i.e., it's tight in one position and loose in another), then it's time for a new sprocket. If the tension stays pretty steady, on the other hand, then your chain problems are probably being caused by something else.

Nice Eric. The mystery of why my chain goes tight and loose while spinning it by hand has been solved. I know the sprocket is worn, but am waiting till the chain is finished, and it won't be long.

 

[MALogger]

The clothesline idea I learned years ago before I had special tools. I have an air gun as well and that does work well too.
As far as the piston stops the ones that screw into the spark plug hole should only be used if the plug hole is straight with the piston but there is another type that you insert through the plug hole and insert it into the exhaust port and that stops the piston too.
This particular piston stop comes with your new stihl if you are good buddies with the mechanic at your servicing dealer. When they prep saws for customers they usually take them out before the saw is picked up.

Instead of all this you could buy a new stihl or husqvarna with outboard sprocket and you only have to remove one little clip and you are in business.

Craig

 

[hydestone]

MALogger - Do you know of any good saw shops in the Lancaster, MA or Bedford, MA area?