Rotary cutter vibration

kornesque

New member

Equipment
L2501, rotary cutter, box blade, disc harrow
May 14, 2023
5
2
3
Low Country
I suppose this is my welcome post so howdy everyone. My RCR1860 has only 10 hours on it but developed a shudder yesterday while I was clearing trails. The effect is much more pronounced when the load is lighter. I checked under the deck when I got it back, nothing big stood out but the blade pivot points are well packed with grass and are rather tight. Spinning by the blades produces a slight wobble of the stump jumper and you can hear a slight bump from near the gearbox as the axle completes each revolution. Oil level and condition are fine. While I prepare to get into it for troubleshooting does anyone have any particular things I should check for or watch out for? I plan to remove the blades to clear the grass but I'm sure there's more to check from the experience here. Thanks kindly.
 

Pawnee

Well-known member

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L2501
Jul 1, 2021
351
306
63
Ontario Canada
Removing the blades is going to require a lot of torque on the bolts. Pulling the grass out bit by bit might be easier.
I had a bad vibration once and it was due to grass buildup under one blade pivot, the blade couldn't swing all the way out and caused an imbalance.
Not sure about the bump from the gearbox, that doesn't sound too good.
 
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kornesque

New member

Equipment
L2501, rotary cutter, box blade, disc harrow
May 14, 2023
5
2
3
Low Country
Removing the blades is going to require a lot of torque on the bolts. Pulling the grass out bit by bit might be easier.
I had a bad vibration once and it was due to grass buildup under one blade pivot, the blade couldn't swing all the way out and caused an imbalance.
Not sure about the bump from the gearbox, that doesn't sound too good.
Yeah, I've watched enough videos to realize it's a bit of a task. I'll try slow and steady first.

I'll try to figure out the source of the bump but I sure hope it doesn't void warranty.
 

Russell King

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L185F, Modern Ag Competitor 4’ shredder, Rhino tiller, rear dirt scoop
Jun 17, 2012
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Check the level of oil in the gear box and the tightness of the bolts holding the gearbox to the deck.

For safety block up the mower with wood if you’re going to be under it.

If there is a cov hole on top of the deck then getting the blade bolts loose is much easier. But a torque multiplier or impact wrench will help

Good luck
 

SDT

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multiple and various
Apr 15, 2018
3,256
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Removing the blades is going to require a lot of torque on the bolts. Pulling the grass out bit by bit might be easier.
I had a bad vibration once and it was due to grass buildup under one blade pivot, the blade couldn't swing all the way out and caused an imbalance.
Not sure about the bump from the gearbox, that doesn't sound too good.
Agreed.

No need to remove the blades unless damaged, needing replacement.

Blades, especially new blades are usually fitted tightly and easily bind with debris.

Remove the debris so that the blades swing freely.

Will not take long for the blades to "wear in."

Should also verify that stump jumper is tightly secured to spindle shaft. If loose, expensive wear of shaft and stump jumper will not take long.
 
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kornesque

New member

Equipment
L2501, rotary cutter, box blade, disc harrow
May 14, 2023
5
2
3
Low Country
Agreed.

No need to remove the blades unless damaged, needing replacement.

Blades, especially new blades are usually fitted tightly and easily bind with debris.

Remove the debris so that the blades swing freely.

Will not take long for the blades to "wear in."

Should also verify that stump jumper is tightly secured to spindle shaft. If loose, expensive wear of shaft and stump jumper will not take long.
Here's a quick video highlighting the thump. I'll get checking the above and report back, thanks.

 

kornesque

New member

Equipment
L2501, rotary cutter, box blade, disc harrow
May 14, 2023
5
2
3
Low Country
Alright, checked gearbox to deck interface, all good. Checked stump jumper rightness, can't budge it and the castle nut looking guy is well pinned and bottomed out. I decoupled the shaft from the rig and gave it a whirl to test the shaft trueness, same issue but I put my ear to the gearbox and it's certainly coming from inside there. I might have a warranty claim on my hands.

I was into some good brush yesterday but didn't hear or feel anything notable until I went no load at the end of the trail. Cosmetically everything appears normal for 10Hrs IMO.

I'll contact my dealer to see what he thinks but if there's any other checks you can think of, please and thank you.
 

GrizBota

Well-known member

Equipment
L3830HST/LA724, B2601/LA435/RCK54-32, RCR1872, CDI 66”grapple, pallet forks
Apr 26, 2023
1,153
736
113
Oregon
Welcome to the forum.

I have the same brush hog. I punished it for over decade cutting anything I could get it over the top of. Including buck brush (manzanita) the size of my wrist. It finally ate the gear box, but it made quite a bit of noise the last three years before that happened. It’s got an aftermarket gear box on it now, which is no where as heavy duty as the one LP put on it.

Anyhow, doesn’t that gear box have a 5 year warranty on it? If so, I’d just use it. I’d be absolutely floored if the dealer decided they wanted to look in to that slight thumping in the gear box, but no harm asking them, other than your time and expense to haul it to them.
 
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Dave_eng

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M7040, Nuffield 465
Oct 6, 2012
5,235
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Williamstown Ontario Canada
Here's a quick video highlighting the thump. I'll get checking the above and report back, thanks.

When you are doing the test in the video, have the pto shaft removed as the articulation of the u joints can produce a rhythmic motion which may produce a noise.
You just want top be only chasing a cutter issue not a pto shaft.
Good luck.
Dave
 

kornesque

New member

Equipment
L2501, rotary cutter, box blade, disc harrow
May 14, 2023
5
2
3
Low Country
I'm not sure what exactly did it but it's no longer shuddering. Besides checking the above I pulled the shaft shrouds to verify I didn't mess up anything when I greased the shaft components a couple hours ago, everything seemed fine. I snapped it back together, ran it through another test and everything feels about how I remember hour 0.

I'll check back in if it rears it's nasty head again but appreciate the inputs. I'm a bit smarter for having gone through that.
 
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