Brush hog vibration

ffmedic

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2012 B3200
Feb 18, 2013
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Richmond, MO
Hi all, I'm a pretty new owner of a B3200. My father in law purchased a 5' Howse brush hog at an auction for me, very cheap. I greased it up, made sure it was full of gear oil. I had to loosen one blade with PB blaster as it was frozen. However, when running it, it vibrates the tractor. More than I think should be normal. The PTO shaft appears straight, the blades were straight and U joints move freely, as do the blades. Is it possible this is normal?
 

Russell King

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L185F, Modern Ag Competitor 4’ shredder, Rhino tiller, rear dirt scoop
Jun 17, 2012
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It is probably that the blades are not balanced to each other or that they are not rotating into the correct position and creating an unbalanced situation. You can try to make sure they are both free to rotate 360 degrees around their connection bolts. I guess you could also just remove the blades and see if the vibration goes away.

I would suggest that you obtain a new set of blades and replace the ones that are on the mower currently. Be prepared to remove large nuts (around 1.5 to 1.75 across flats) to get the blades off and then need to get them tightened up to about 250-300 foot-pounds (more than most 1/2 drive torque wrenches will go to)

That way you know that they are balanced and free.

Be sure that you know which side is top and which side is bottom before removing the old blades (write "bottom" on the blades with a paint pen before taking them off).

You can also compare the old to the new to see if you can find out if the old blades are missing "chunks" to create unbalance.
 

ffmedic

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2012 B3200
Feb 18, 2013
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Richmond, MO
Thank you for the advice. I was afraid of that. By the time I buy a 3/4" impact and new blades, I'd be equal to the cost of it ($220). Maybe I should try and sell it and start over.
 

Russell King

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L185F, Modern Ag Competitor 4’ shredder, Rhino tiller, rear dirt scoop
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Then go the cheap(er) route and just take the blades off and see if that also removes the vibration. You should be able to get a socket and get the blades off for less than $50 (assuming you already have the breaker bar).

Its not too bad to get them off (assuming that there is a port on the deck to get to the nuts through). Then you can see if you can get them back to balanced condition.

You don't need to have an impact to do any of the removal or install. You can really do it all with the tools you have except for the socket. I got mine at NAPA for ~$25. Use a caliper on the nut to measure the size. Mine happened to be a 42mm but I have a different brand mower.

You may be able to down load a manual from the Howse website.
 
Last edited:

Russell King

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Jun 17, 2012
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Oh and verify that the bolts that are attaching the gear box to the deck are tight also. That could also cause vibration problems if it is loose.

Don't give up too soon!
 

ffmedic

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2012 B3200
Feb 18, 2013
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Richmond, MO
Thanks! Just like everything else on our new-to-us farm, it needs some elbow grease. I'll remove the bolts by hand (I do have an access hole in the deck) and see if that helps. Although, depending on price..I may replace those blades, they looked pretty rough. I just don't want to tear up my new tractor (26 babied hours)
 

Russell King

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This will be easier with it attached to the tractor so it doesn't move around too much. Also use some of the PB blaster on the nuts a while before you want to get the nuts off.

Remember a cheater pipe is your friend. I actually used a "come a long" between the tool and the mower to break the nut loose - I did not have a cheater pipe handy nor am I all that strong.

Captain Safety says DON'T work under the mower unless it is well supported (blocked up) not just held up by the tractor.

On mine (Modern Ag) the blades had a model number stamped into them. Looking on line I could get two sets of blades shipped to me for the price of one set at the dealer. Tractor Supply did not have the ones I needed - the blades are very specific to the mower for some unknown reason. It would probably pay off to look around for them a little

And again - identify the bottom of the blade before you take it off - I used a paint pen but I guess even a spot of paint would be good enough.

Good luck and keep at it.
 
Last edited:

Russell King

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L185F, Modern Ag Competitor 4’ shredder, Rhino tiller, rear dirt scoop
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I just thought of something else.

On mine (and most) brush hogs, the blades attach to a stump jumper. This is a large circular disk that covers the center of the mower and the blades attach to it. The edges turn up (like a dinner plate) so it will go over obstacles.

If yours has been sitting around for some time, there may be something built up on top of the stump jumper. You can probably see most of the top of the stump jumper through the access hole for the blade nuts. Remove the PTO drive shaft from the tractor so you can rotate the PTO shaft to turn the stump jumper through 360 degrees to see if you can find something.

Here in Texas we have a wasp called a "dirt dauber" that can build up a fairly heavy nest of mud that would probably be big enough to cause a problem.
 

MagKarl

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L245DT
Aug 2, 2010
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Make sure all the fasteners are tight.
Measure the blades with a tape measure and verify that they are the same size.
Make sure the blades can swing easily where they are fastened to the pan.
Verify that your driveline u-joints and slip joint are lubed.
Rotate the blade by hand and verify smooth, quiet rotation.

If all that checks out, try working it a bit. It's not going to be smooth like a lawn mower.
 

G-Man

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B7500, ZD221
Jul 27, 2012
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Excelsior, AR
You need new blades. When I purchased my used tractor it came with a brush hog and it had vibration issues. I pulled off the old blades and compared to the new blade I bought and boy where they worn. After the new blades installed, bingo no more vibrations.
 

ffmedic

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2012 B3200
Feb 18, 2013
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Richmond, MO
Thank you guys for all the advice and help. Upon further inspection this morning, I noticed one blade is about an inch shorter than the other. Now the fun begins!
 

ctmike

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May 10, 2013
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Just one more thing to check after you replace the blades is to make sure the driveshaft is in phase.
What this means is that the U-joints are lined up correctly. If you pull the 2 drive shafts apart, you'll notice that it can go back together 2 or 3 different ways. Rotate the half shaft so that the ears on the u-joint on one end are facing the same way on the other end.
If it's out of phase, it doesn't cause a lot of vibration but it is noticeable.
 

WFM

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I'm always amazed at the amount of knowledge a lot of folk have here.
 

Russell King

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Glad you found the problem.

don't get too wrapped around the axle on having all the right tools to do this with. I used a caliper to measure the nuts to make sure I got the correct size socket. IF I had a large set of SAE size sockets I would have found one that would work. Like I said before I then broke the nuts loose with a cable puller on the wrench handle to another spot on the mower. I then lubed everything back up with anti seize and installed the new blades and tightened the nuts up to 150 foot pounds using a torque wrench. I used the amount of effort on that pull to estimate how hard to pull on a cheater bar that was twice as long as the torque wrench handle. Good enough to ensure the blades stay on.

Eventually I will save up a bit of money to buy a torque multiplier from Northern Tool so I can use it to loosen and tighten all the things that need a bit of coaxing over what I can do with normal efforts.

Only wish I had bought the socket with a 1 inch drive since that is what the torque multiplier output is.
 

Stubbyie

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Jul 1, 2010
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Contact Howse and wait on them to send you the Owner's Manual for that machine. You'll need to furnish them the Model Number off the tag. If not present they can guess pretty well based on your description. You may need to send them a photo via email.

Howse blades can be hard to find in some areas. You said you had two different blade lengths----one's been cut off, ground off, or you have one or both incorrect blades. You need to start fresh with the OEM part number or you'll never get it right. Howse will have a number stamped on them somewhere if not worn off.

There are literally hundreds of different bushhog blades--make certain you have the correct offset and direction of rotation and mounting hole size---in addition to length.

Locally, I pay about $50 for a set of two blades for a 6-ft Howse.

You might want to go back with new mounting bolts. Make sure the stumpjumper keyway slot is clean and make certain when reinstalling bolts the keyways line up.

Check local pawn shop for large sockets, extension, and break-over bar or buy a bushhog wrench to fit. Use a cheater pipe and penetrating oil. Lube the threads and keyway with thread sealant (pipe dope, not LocTite) when going back together.

After removing the nut the blade bolt will probably be tight. Put the nut back on just to top of bolt and use a piece of wood to punch the bolt loose.

Sharpen blades annually or as needed by removing and using a 4.5-in hand grinder.

Check gearbox and use 85-140-W gear oil or per Howse specs. Some of their gearboxes have a level indicating plug, some don't.

Tighten EVERY nut on the entire implement and go back with new NyLock nuts.

Blades can, do, and will bend and break. First time it happens you'll have a strong desire to be someplace else. Get out of PTO as fast as you can, go back to shop, and install new blade set. Retighten all bolts, again.

Keep those U-joints greased. Replace missing zerks (one each end). Look carefully, may be sheared off.

Please keep us all informed regarding your continuing experiences that we may all learn.
 

Eric McCarthy

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Just one more thing to check after you replace the blades is to make sure the driveshaft is in phase.
What this means is that the U-joints are lined up correctly. If you pull the 2 drive shafts apart, you'll notice that it can go back together 2 or 3 different ways. Rotate the half shaft so that the ears on the u-joint on one end are facing the same way on the other end.
If it's out of phase, it doesn't cause a lot of vibration but it is noticeable.

Back in my tow truck/wrecker driving days if we pulled a drift shaft out of a truck and had to put it back in this process was know as timing the drive shaft. It was told to me if installed wrong it could cause damage to the transmission and rear axle.