MX6 Brush Hog Shakes Tractor?

Bliz · Jul 15, 2009

I have a JD 6115D tractor with an MX6 brush hog that I loaned to my neighbor to mow a field. When I got the machine back the tractor shakes like crazy when using the mower. I have checked the blades, the stump jumper and the pto connections and I don't see anything unusual or damaged. The gear box on the mower is not making any noises so I assume that is OK. Does anyone have any suggestions on what else to check? Thanks for any info.

Ken · Jul 15, 2009

The blades and stump jumper are the flywheel for the bush hog. so if a blade cannot run freely it will cause out of balance vib. Mine catches wire and wraps around blade to cause the out of balannce feeling.
Also lower RPM will allow the blades load up with grass and brush then vibrate.
Check if a blade is warped or bent hitting some part of frame.
My MX6 usually vibration free. but gets noisy when above conditions happen.
ken

Acolar · Jul 15, 2009

I purchased a RC 1072 for my 3520 and had to send the first one back as the stump jumper was bent - probably due to fork lift fork damage during handling. The disc was distorted which did not allow the blades to rotate freely - wow did it shake everything!

I also found that after heavy/prolonged mowing the blades would collect junk around the bolts which attach them to the disc. I removed the blades for sharpening and cleared out all the junk form around the bolts and noticed a much smoother operation of the rotary cutter from inside the cab.

Tony

lwalsh · Jul 15, 2009

Measure the distance from the blade to the deck, rotate the next blade to the same position and measure again. Much difference and I'd say the stump jumper or the gearbox output shaft is bent.

Uncle Wayne · Jul 16, 2009

Bliz said:
I have a JD 6115D tractor with an MX6 brush hog that I loaned to my neighbor to mow a field. When I got the machine back the tractor shakes like crazy when using the mower.

Bummer. I'm betting the stump jumper or gear box shaft is warped. Good luck.

tommu56 · Jul 16, 2009

Make sure the blades are free i had one that was binding on grass and and got stuck almost 180 degrees out of place and my mower was hopping around like a kangaroo!

I had to loosen blade clean out grass and set it back up again.

tom

Bliz · Jul 16, 2009

Thanks for the advise. Yesterday I pulled the shrouds off the pto shaft to check for any damage or bending and that is fine. I did find that when I measured the distance from the stump jumper disk to the top of the mower on opposite sides there is a 1.25" diffference. So I think the advice of a bent stump jumper or shaft is correct. We will be taking it apart to figure out which one. My guess is it is the shaft as the stump jumper appears OK. How big a job is it to change the shaft?

jenkinsph · Jul 16, 2009

May take most of the day. It would be adviseable to have some help with the heavy stuff. When you are done make sure the slip clutch is adjusted properly too.

Bliz, In the borrowers defense that is a lot of power to turn an MX 6, I think it has a 90
hp gearbox. Hope he is helping out with the repairs.

Steve

Bliz · Jul 16, 2009

jenkinsph, I know the mower is kind of small for that tractor but figured it would be ok as I usually only mow my own field with it. I had a 4720 tractor when I bought the mower and upgraded to the 6115D because I plan to log with it this winter. My saleman stopped by yesterday to take a look at it to see if he could tell what the problem was. I was not home at the time and he loaded it on a trailer and took it back to the shop to be checked out. Thanks again to all for the help.

ddivinia · Jul 16, 2009

Bliz said:
jenkinsph, I know the mower is kind of small for that tractor but figured it would be ok as I usually only mow my own field with it. I had a 4720 tractor when I bought the mower and upgraded to the 6115D because I plan to log with it this winter. My saleman stopped by yesterday to take a look at it to see if he could tell what the problem was. I was not home at the time and he loaded it on a trailer and took it back to the shop to be checked out. Thanks again to all for the help.

Most damage to those mowers is not HP related. I have seen them up at the shop with the hole pan sheared off, etc. Hit something going too fast, etc.

D.