string trimmer question


Old 10-10-05, 04:52 AM
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string trimmer question

I have a Sears gasoline string trimmer (weedwacker). The stopped working last week. when engine is running, the string head does not rotate. I suspect the flexible shaft is broken. After I took it apart, I could not see any broken part. Both ends to the shaft are square. One end connects to the gear assembly of th string head. The gear assembly has a cylinder with a square hole in the middle. I assume the end of the shaft should connect to this cylinder. But, it seems the shaft is not long enough to reach that cylinder. So the movement at engine side cannot be transmitted to the string head.

I don't think the shaft is broken. Why it is unable to reach the gear assembly? Is there anything that holds the shaft in the right position so that it can correctly connect to engine and the string head? I spent couple of hours on it and could not figure out why. Any help will be greatly appreciated.

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Old 10-10-05, 06:40 AM
Join Date: May 2005
Posts: 20
Check and see if the whole shaft assembly will slide towards the engine assembly. There may be a bolt or two near the throttle handle that you will have to loosen and then slide the shaft assembly towards the engine assembly. From vibration, the engine assembly can slide backwards away from the shaft and the flexible shaft comes out of the socket on the engine.
Old 10-10-05, 12:06 PM
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When i took the string trimmer apart. I found the flex shaft slides freely inside of the long tube. Is it normall? When i push the shaft to the engine, I could feel the squared end was attached to something because I could not turn it any more. With this position, the shaft could not reach the string head at the other end. If I push the shaft to the string head, other end was completely separated from the engine.

In normall situation, how does flex shaft connect to the engine and how does it make the contact to the string head? In general, what mechanism is used to ensure correct distance between the engine and string head so that the shaft can carries the power from engine to the grass cutting parts?
Old 10-10-05, 06:01 PM
Join Date: Jul 2005
Location: central il
Posts: 154

lets see, if i can mention a few things 4 you.

the shaft wire, does come out, I have seen it held in 2 ways. 1 with just inserting into the hex head at both ends. the clutch and at the string end.

the other way at the clutch there is a bolt that you tighten to hold into place.

You can push it in 2 far for it not to fit into the other end.

Also make sure its not short on one of the hex ends. they both should look the same, the hex end.

Sometimes, grass gets all bound up in the tube that connects to the trimmer head and will not turn freely. Also the bolt that screws onto the tubing that hold the inner wire and connects to the end of the trimmer, plastic end (string) if it is over tightened, it will not turn freely.

Old 10-11-05, 02:53 AM
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Join Date: Apr 2004
Location: Upstate New York
Posts: 3,224
I'd say if you in fact have everything assembled fully, then you do have a broken flexible drive shaft. It just may have made a clean break and doesn't appear to be broken. Ideally, you'd like to find a local dealer who has one in stock so that you can compare yours to it. A remote possibility is that you have a defective centrifigul clutch on the engine.
Old 10-12-05, 04:50 AM
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Thanks for the info from everyone. I got my string trimmer fixed.

After seeing Mizzleman's response, I realize I did not check the connection between the flex shaft housing tube and the engine. If there is not broken part, the only logical explaination of the problem would be the housing tube moved away from engine and increased the distance between engine and the trimmre cutting head, and the resulted the disconnect between shaft and engine.

I took off the throttle trigger handle and found the housing tube can be easily pulled off by handfrom the engine side. There is a clamp that attaches the housing tube with engine. The screw on the clamp was loose. I pushed the housing tube back to the engine and tighten the clamp. Then, the string trimmer started working again.

I really appreciate your help!

Old 10-12-05, 07:23 AM
Join Date: May 2005
Posts: 20
Good deal! Glad you got it working!

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