flywheel key or key way

Discussion in 'Mechanic and Repair' started by LadyBloom8, Aug 11, 2005.

  1. LadyBloom8

    LadyBloom8 LawnSite Member
    Posts: 3

    flywheel key or key way...witch ever u want to call it
    i start the motor and with in 10 sec u can tell that it had broken..take it all apart and yep, the key is broke has done this 4 times...
    would anyone know why it would keep shearing the key?
  2. greywynd

    greywynd LawnSite Member
    Posts: 132

    More information, such as type of motor etc, would help. In a push mower for example, the flywheel 'key' will sometimes shear when the user has struck an object, It's a sort of safety mechanism to prevent the rotating flywhhel from bending/damaging the flywheel when the blade comes to a sudden stop. If there is no other problem, I would have to wonder if it's the correct key, if it's the wrong size it may shear just from the loading on it. Maybe once you can tell us more someone might have more help for you.
  3. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,023

    Sounds like under torquing the flywheel bolt to me, Post the model and spec. numbers as greywynd suggested and we can get you the proper torque setting. And I have seen people oil or grease the end of the crank thinking it will keep it from rusting, While it does it also causes this problem so always install flywheels dry. By using this method and applying the proper torque spec. you shouldn't have a problem.

    You can pull the plugs and rotate the te engine by hand clockwise till one of the pistons reach top dead center compression stroke. Then rotate it back counterclock wise about 2" and feed about 4 or 5" of # 4 1/2 recoil rope into the plug hole leaving enough sticking out to remove it when done. This will hold the engine from moving while torquing.
  4. LadyBloom8

    LadyBloom8 LawnSite Member
    Posts: 3

    thank you for the feedback guys
    i found out that it is a briggs 10 horse
    does that help?
  5. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,023

    That is close enough, Torque the flywheel to 65 ft. lbs.
    Good Luck
  6. LadyBloom8

    LadyBloom8 LawnSite Member
    Posts: 3

    thank you guys, we will try that!

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