What are the indicators of a bad clutch

[bplust]

I ask, because I do not know. I've had maybe 200 saws total in my possession, some I just put a fuel line in, and some I've replaced cranks. But I'm not sure of the symptoms of a clutch that's "on the out", or of one that's completely toast. I can tell if a bearing is good or not, and I'm aware enough to see a broken clutch spring, but I don't think I've ever experienced a bad clutch.

Thanks in advance for any replies, many of you have been an invaluable resource, or at least worth a good laugh.

 

[Roanoker494]

It usually goes one of two ways. They either they slip while cutting, or it will not pull the chain at all, or they lock engaged all the time because of a weak spring or some kind of mechanical issue like rust. I have one here now that you can pull the chain by hand and it will turn the engine over, that most certainly ain't right. Sign of a weak spring would be the chain spinning at an idle no matter how low you set the idle screw.

 

[fearofpavement]

Yeah, what Roanoker said.

 

[bplust]

Yeah, what Roanoker said.

I tend to say the same thing.

 

[NuggyBuggy]

Sign of a weak spring would be the chain spinning at an idle no matter how low you set the idle screw.

I hope I am not hijacking, but I was just about to post exactly this problem. My 076 is pulling the chain at idle, and lowering the idle screw does nothing until the saw dies. I did some fiddling with the low carb screw but couldn't affect this much.

At first I thought it might be a bad clutch spring, but:
1- the clutch spins freely into the drum, and
2- the chain moves when the starter rope is pulled even slightly.

Am I right that this is not likely a clutch problem ? Could the clutch and surrounding components be assembled wrong ?

 

[Roanoker494]

Sounds like you may have a bad clutch spring. The spring is suppose to hold the shoes in until a certain RPM, sounds like your spring is releasing the shoes way to early. Make sure the there is no debris between the clutch shoes and drive sprocket.

 

[w8ye]

Often, in addition to weak springs, you can get an indication of clutch wear by looking at the shoes themselves. Most have a more or less a wear indicator molded into them. This is especially noticeable when comparing a high time clutch shoe with a new one. Or you can compare your shoes with pictures of new ones on the Internet.

Also on the clutch drum, the shoes can wear a groove inside the drum. You can feel this with your fingernail. If you can determine that there is a groove, you should replace the drum.

 

[NuggyBuggy]

Sounds like you may have a bad clutch spring. The spring is suppose to hold the shoes in until a certain RPM, sounds like your spring is releasing the shoes way to early. Make sure the there is no debris between the clutch shoes and drive sprocket.

You're probably right, but what I don't understand is how could pulling the starter rope even a little bit move the chain, while still being able to spin the clutch freely into the drum without the shoes catching the drum ? Is it a gearing thing where pulling the starter actually generates a lot of RPMs for even a little bit of rope travel, while spinning the clutch into the drum doesn't generate enough RPMs to release the shoes ?

I will check that everything is clean, but I did disassemble and reassemble several times with no effect and everything did feel pretty clean. I should say I have TWO 076s that are doing the same thing but I haven't toyed with the second one.

 

[fearofpavement]

The clutch area is the only way rotational force can be given to the chain drive sprocket. There is a problem with your clutch. May just be dirty. Can't be anything else. Take it apart and look at it. It may be assembled incorrectly. Find a parts manual and make sure everything is in the correct order. If both of your saws are doing the same thing, they may have the same problem. Is this "new" or has it been that way?

 

[NuggyBuggy]

The clutch area is the only way rotational force can be given to the chain drive sprocket. There is a problem with your clutch. May just be dirty. Can't be anything else. Take it apart and look at it. It may be assembled incorrectly. Find a parts manual and make sure everything is in the correct order. If both of your saws are doing the same thing, they may have the same problem. Is this "new" or has it been that way?

You're right... it has to be the clutch or something right there. If it's dirt, it would have to be between the shoes and the drum, correct ?The shop manual also suggests the needle cage might be damaged... if its badly out of round or something could pulling the starter rope could turn the sprocket without even engaging the clutch ? But then would it even fit in the sprocket ?

Both saws are new to me. When I got the first saw, it came without bar, and with a .404 rim sprocket. I took it to my dealer and had them install a 3/8 rim sprocket. When I mounted bar and chain, I noticed that *sometimes* the saw pulled over without any fuss, and other times I was pulling my shoulder socket out... it was then that I noticed that pulling the starter rope even a bit was moving the chain. And even after that, sometimes the starter would be impossible to pull, and other times it would pull just fine.

The shop manual says the raised portions of the washers are supposed to press against the clutch carrier... which I believe is how I had it reassembled when trying to figure things out. When I see my saws this weekend, I'll try cleaning the parts out. Sadly, my local dealer says they have a 2-week backlog on tune-ups and such. By then, I fear there will be too much snow on the ground for me to want to do much milling.

 

[Patrick1903]

How’d those clutch issues turn out 10 years ago with your 076s?