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Hello All.

So, I am a few weeks into using my recently acquired 1998 LT155 and am having an issue with the deck vibrating excessively and making a noticeable noise when running. The engine is running smooth with the PTO disengaged and does not surge or miss a beat. When the deck is engaged, I can not only see the PTO level vibrating a lot, but I can also feel the entire mower shaking and there is a "pulsing" hmm coming from under the mower.

When I purchased the mower I replaced the deck spindles, idler, pulley, sheave and belt with genuine OEM parts. I also removed the TriCycler kit and equipped the deck with the the OEM High Lift Blades as I only side discharge on my lawn.

I initially noticed a difference in the vibration the first time that I used the mower with the repairs made, but it seems like it is vibrating more than ever and the humming from the deck is louder as well. The blades are free of damage and are not bent.

I am not used to or very familiar with mechanical PTO's and am wondering what all could be causing this problem? Since there isn't a typical tension spring pulling on the idler arm, could it be a problem with "weak" spindle breaks which I believe to be what applies the tension to the belt?

I appreciate any help or insight that you might provide.

Mike

cruzenmike said:

Hello All.

So, I am a few weeks into using my recently acquired 1998 LT155 and am having an issue with the deck vibrating excessively and making a noticeable noise when running. The engine is running smooth with the PTO disengaged and does not surge or miss a beat. When the deck is engaged, I can not only see the PTO level vibrating a lot, but I can also feel the entire mower shaking and there is a "pulsing" hmm coming from under the mower.

When I purchased the mower I replaced the deck spindles, idler, pulley, sheave and belt with genuine OEM parts. I also removed the TriCycler kit and equipped the deck with the the OEM High Lift Blades as I only side discharge on my lawn.

I initially noticed a difference in the vibration the first time that I used the mower with the repairs made, but it seems like it is vibrating more than ever and the humming from the deck is louder as well. The blades are free of damage and are not bent.

I am not used to or very familiar with mechanical PTO's and am wondering what all could be causing this problem? Since there isn't a typical tension spring pulling on the idler arm, could it be a problem with "weak" spindle breaks which I believe to be what applies the tension to the belt?

I appreciate any help or insight that you might provide.

Mike

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So you're saying you don't have an Electric PTO but, a lever and cable that you apply to manually engage your deck?

The 155 is not an electric PTO. Mechanical lever moves pulley to tighten belt. Might want to check deck belt tension with lever engaged. Not enough tension can cause deck vibration

Vibratiopns are usually caused by
1) Blades bent or out of balance
2) DAMAGED BLADE SPINDLES
3) DAMAGED PULLEYS
4) damaged belt

If the tension in the belt is not enough then the blades will stop spinning or radically slow down in heavy grass.
The brakes do nothing but stop the blades rotating ( legal requirement ) and this has a secondary function of concentrating the belt slack at the engine pulley.
If the brakes are touching the pulleys with the blades engaged they need to be adjusted .
Also check the holes in the tension lever that activates the brakes, they do flog out oval so the brakes can drag but this is rare on JD decks.

Thank you for the replies. I will go ahead and check all of these things. Seeing as most of the deck parts are new, and since the problem was only really noticeable after I put on the high lift blades, I am going to try to check the blade balance and possibly even swap back to the mulching blades and see if the problem persists. I am quite certain that the linkage for the PTO is okay as the posts align with the holes perfectly when installing the deck.

I will investigate and report back.

Mike

So I took the high lift blades off today and I am quite certain that one of them is off balance. These blades are brand new and used only once. And I have not hit anything with them. I am quite disappointed with this considering that I am buying the OEM parts from the dealer. There may be some error in my looking at the balance as I am just using one of the Arnold blade balancers and the new Deere blades have the star pattern making it hard for them to center on the top of the cone. I did put the TriCycler mulching blades on to the balancer and they appeared to sit level. One thing that I did also think of is that between my 2nd and 3rd cut, I did raise the engine RPM about 200 to get it up to factory spec of 3400 top no load. It is now starting to make sense that if there was a balance issue, the added engine RPM at full throttle would make that vibration more severe and the noise coming from the deck louder.

I am going to give the John Deere Dealer a call tomorrow and explain what is going on and see if there is anything that they can do for me. I doubt it since the blades are used now, but at the very least I can look into a different blade. I have researched a found that Oregon makes a "100 Series" blade which has an extra long cutting edge as well as a low lift sail that extends along the whole back of the cutting edge instead of just the tip being turned up. I guess in all there are about 4 OEM blade options and at least 4-5 aftermarket ones. I want to find the best balance of deck noise, minimal power consumption, cut quality and clippings dispersal. This might take some trial and error. In the end, I hope that whatever blades I try, the noise and vibration goes away.

Oh yeah, I did check the pulleys, idler and sheave and they all looked okay. Belt is also good too. So maybe it was just the blade.

Somewhat dissapointing
in the past 7 years I have only ever had 1 set of blades that were out of balance from new
I have the same balance checker as you are using, most just use a nail on he wall
What has caught me out was a couple where the flutes were not identical at each end and the supplier replaced them without question.

So, I took the high lift blades up to the dealer and they exchanged them without issue. I have not had a chance to put them on but I did put the wavy mulchers back on, all sharpened, but without the deflector/baffle that is part of the TriCycler kit. To be honest, the mower did very well with this configuration. Not only did it cut well with no clippings left uncut, the deck was much quieter and smoother than with the high lift blades. I also feel as if the discharged clippings were smaller as well; likely the result of a much longer cutting edge and wavy blade design.

This has me excited about the though of a Gator Blade maybe improving my experience with side discharging. I would probably go with the G3 which is still only 2.5" wide and has about a 3/4" lift on the back side. I believe that these blades will do well as they too have a long cutting edge but will also rob the engine of less power with their slightly lower lift compared to the OEM high lifts.

If I get a change to pick the blades up J will report back. I look forward to trying all the various combinations of blades and chute blockage when leaf season comes.

cruzenmike said:

So, I took the high lift blades up to the dealer and they exchanged them without issue. I have not had a chance to put them on but I did put the wavy mulchers back on, all sharpened, but without the deflector/baffle that is part of the TriCycler kit. To be honest, the mower did very well with this configuration. Not only did it cut well with no clippings left uncut, the deck was much quieter and smoother than with the high lift blades. I also feel as if the discharged clippings were smaller as well; likely the result of a much longer cutting edge and wavy blade design.

This has me excited about the though of a Gator Blade maybe improving my experience with side discharging. I would probably go with the G3 which is still only 2.5" wide and has about a 3/4" lift on the back side. I believe that these blades will do well as they too have a long cutting edge but will also rob the engine of less power with their slightly lower lift compared to the OEM high lifts.

If I get a change to pick the blades up J will report back. I look forward to trying all the various combinations of blades and chute blockage when leaf season comes.

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Yeah...you gotta try a few things and a few different things to find out what works best for you and your mower!
You can quote me on this "just because it's new....don't mean it's good"

Just wanted to give an update on the blade and deck situation:

I have fitted the LT155 with some Oregon Gator G3's this past week. I have mowed with them a few times and have to say that there may be something to the vibration that comes from the higher lift on the blades. I do not notice any abnormal or significant vibration/noise when using the wavy mulchers. With the G3's I get a little bit of vibration and some droning noise. The cut performance of the G3's is okay, but I am realizing that much of my experience with this machine is being driven by my often-times dense and tall turf along with the machine being underpowered. I can honestly say that the best overall cutting performance is with the wavy mulching blades while side discharging. I still keep experimenting with different cut heights and blade types. No matter what I do I still get a nice clean and even cut with the baffle/chute block removed.

If the Gators were put on properly and done up tightly then your spindle bearings are suspect.
Gators are noisier than std blades but there should be no difference in vibrations.

bertsmobile1 said:

If the Gators were put on properly and done up tightly then your spindle bearings are suspect.
Gators are noisier than std blades but there should be no difference in vibrations.

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Deck spindles are new. Also new deck belt. I am quite positive the blades are installed correctly as well. I am thinking that it could be a belt tension issue? I have not attempted to tighten anything. There is a spring and something in the rod that connects the PTO lever to the deck. I think that there is also a spring somewhere inside the idler arm where it mates to the deck. I believe the spindle brakes properly adjusted without any drag as well.

I will have to get under there this week and double check that everything is tight and adjusted properly.

You could try taking off one blade at a time and then run it.

I took the idler arm off of the deck which has a bushing that appears to have a small groove in it. Because of this groove, there may be some wobbling of the idler arm. I am going to replace that bushing and see what it does. But here is my question: since the deck does not have the typical spring on the idler providing constant tension to the belt, where does this deck get it's belt tension from? I know that engaging the pto provides the initial tension bay simply shortening the distance between the drive pulley and the idler pulley, but once engaged, something has to keep tension and allow for intermittent slack in the belt during heavy loads and through deck movement. It can only be the spindle brakes or the spring in the PTO linkage. I have included pictures of both. Which one, if "failing" would result in a loss of, or weaker tension on the deck belt?

Thank you.

IF you can, make up some spacers to replace the blades then try the deck
GAtors do put a higher load on the deck system so I see where you are coming from with the belt tension idea but it would be good to rule out silly things like a bad belt first before you rip all of your remaining hair out.
One of the few new belt problems than turned me into a chrome dome was a tranny belt with a bulge in it

bertsmobile1 said:

IF you can, make up some spacers to replace the blades then try the deck
GAtors do put a higher load on the deck system so I see where you are coming from with the belt tension idea but it would be good to rule out silly things like a bad belt first before you rip all of your remaining hair out.
One of the few new belt problems than turned me into a chrome dome was a tranny belt with a bulge in it

Click to expand...

I replaced the belt two months ago, but that doesn't mean that it is still good. I will thoroughly inspect it once I have the bushing back in and all the other deck hardware back in. I am hopeful that the new bushing will resolve the wobble in the idler and improve the vibration.