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  1. #1
    Member
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    Feb 2009
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    NW MO

    Default brush hog shaking

    I've got a 5' brush hog don't know the brand it's beat up and I bought it used for almost nothing. I've used it for 2 or 3 years and it's always shaken a little bit but when using it yesterday the shaking has really picked up. I crawled under and made sure the 'hinge' points on the blades are free and they are though it does take some effort to 'swing' each blade. Should I lube the blade 'hinge' points? The gearbox does leak but I'm pretty good at keeping 90wt in it. Any suggestions? Thanks - Coldstream

  2. #2
    Platinum Member psj12's Avatar
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    Oct 2005
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    518
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    Short OK
    Tractor
    KIOTI 554

    Default Re: brush hog shaking

    take the blades off and check to see if they actually weigh the same. Sometimes when one is damaged it will be replaced with a similar aftermarket blade od a different weight. Also check to make sure your drive shaft is not bent.

  3. #3
    Gold Member HarryN's Avatar
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    Aug 2011
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    Covington, Louisiana USA
    Tractor
    1999 Bobcat 763F John Deer 850 Grasshopper 723K H2

    Default Re: brush hog shaking

    When you take the blades off, do sharpen them and like psj12 said, make sure they weigh very close to the same. Not quite as critical as a lawn mower blade but need to be pretty close.
    And, YES, lube up the pivots good. Which allows the blades the ability to easily straighten out during rotation.
    If that does not solve the vibration problem then I'd be looking at the gear housing, shaft, etc next.....

  4. #4
    Epic Contributor Bird's Avatar
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    Mar 2000
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    Texas

    Default Re: brush hog shaking

    As psj12 said, the weight of each blade should be the same or very close, but to answer your other question, those blades should swing quite freely, so I'd want to know why they don't.
    Bird

  5. #5
    Bronze Member
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    May 2013
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    51
    Location
    McKinney, TX
    Tractor
    JD 4700, BX2670, RTV900XT

    Default Re: brush hog shaking

    Quote Originally Posted by coldstream View Post
    I've got a 5' brush hog don't know the brand it's beat up and I bought it used for almost nothing. I've used it for 2 or 3 years and it's always shaken a little bit but when using it yesterday the shaking has really picked up. I crawled under and made sure the 'hinge' points on the blades are free and they are though it does take some effort to 'swing' each blade. Should I lube the blade 'hinge' points? The gearbox does leak but I'm pretty good at keeping 90wt in it. Any suggestions? Thanks - Coldstream
    Something is out of balance…could be a blade, u-joint is bad, or the gearbox. Start with the easy stuff.

  6. #6
    Platinum Member
    Join Date
    Mar 2012
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    514
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    Cos, N.H.
    Tractor
    Kioti LK3054xs

    Default Re: brush hog shaking

    If it was a balance problem, why would it have gotten worse? Almost sounds like a bearing in the gearbox...of course not to say that an imbalance wasn't the cause of the bearing failure.

  7. #7
    Old Timer Soundguy's Avatar
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    Central florida
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    ym1700, NH7610S, Ford 8N, 2N, NAA, 660, 850 x2, 541, 950, 941D, 951, 2000, 3000, 4000, 4600, 5000, 740, IH 'C' 'H', CUB, John Deere 'B', allis 'G', case VAC

    Default Re: brush hog shaking

    blades should swing freely.

    don't lube the pivots. it will attract dirt and become a grinding compound. those bld bolts should be shouldered and only tighten to captur ehe blade. check for strings and grass int he blad pivot area.

    also check that the stump jumpe ris not loose ont he output shaft. measure each blad and see if it is close in shape / size ( if you don't take them off and weight..e tc. )

    stump jumper look bent?


    if the gearbox leaks a lil.. when you top off with 90w.. try 85/140 instead and put in a few shots of #2 gun grease at each top up. makes it thicker and less likley to leak.
    souNdguy

    sent from my NOKIA LUMIA

  8. #8
    Bronze Member
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    May 2013
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    Location
    McKinney, TX
    Tractor
    JD 4700, BX2670, RTV900XT

    Default Re: brush hog shaking

    Quote Originally Posted by Oaktree View Post
    If it was a balance problem, why would it have gotten worse? Almost sounds like a bearing in the gearbox...of course not to say that an imbalance wasn't the cause of the bearing failure.
    A bad ujoint can throw a shaft out of balance. rpm*out of balance = shake. Like I said, could be ujoints, bearings, blades. I would also check the attachment points. The shake may be worse from a loose implement.

  9. #9
    Member
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    Feb 2009
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    NW MO

    Default Re: brush hog shaking

    Thanks guys for all of the input. I will check it out and report back.

  10. #10
    Member
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    Feb 2009
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    Location
    NW MO

    Default Re: brush hog shaking

    I wanted to wrap this issue up, might help somebody in the future. Based on the suggestions here I mounted the mower and got under it (with jack stands as a safety back up). The blades would pivot but they were rather stiff. A lot of old grass and debris had worked it's way into the pivots. After some scraping with a putty knife and screwdriver and a shot of knock er loose they were swinging very freely. I saw no noticeable damage to the stump jumper or the blades. I then topped off the gear case with 85/140 and lubricated the u-joints (which looked to be in good shape. This thing runs smooth as glass now. It's like having a new mower! Thanks guys! Coldstream

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