Mulching Issue with poor quality cut while mulching with my ZT-52HD

• The blade tips are worn.
• Your overlapping may be insufficient: The tires push down grass during each pass. If you line up your tires with tire marks from the previous pass, the grass does not get a chance to stand back up during either pass. Overlap more than the width of your tires on subsequent passes. This will allow the blades to draw up the trampled grass from each previous pass and should produce a nicer looking cut.
• Right hand turns: Twin-blade mower decks are designed with the discharge on the right side. The left blade is positioned slightly forward and in front of the right blade. During left turns this cutting overlap is maintained. This provides cutting overlap when traveling in a straight line. The tractor operator should therefore make mostly left-hand turns when cutting grass.
• Improper cutting deck adjustment: This can produce a vacuum imbalance that, under certain circumstances, causes airflow to push outwards from the front of the cutting deck. Consult your tractor Operator's Manual for specific Deck Leveling and Deck Engagement adjustments pertaining to your specific model tractor.

lawn mower fanatic said:

These are some common reasons:

• The blade tips are worn.
• Your overlapping may be insufficient: The tires push down grass during each pass. If you line up your tires with tire marks from the previous pass, the grass does not get a chance to stand back up during either pass. Overlap more than the width of your tires on subsequent passes. This will allow the blades to draw up the trampled grass from each previous pass and should produce a nicer looking cut.
• Right hand turns: Twin-blade mower decks are designed with the discharge on the right side. The left blade is positioned slightly forward and in front of the right blade. During left turns this cutting overlap is maintained. This provides cutting overlap when traveling in a straight line. The tractor operator should therefore make mostly left-hand turns when cutting grass.
• Improper cutting deck adjustment: This can produce a vacuum imbalance that, under certain circumstances, causes airflow to push outwards from the front of the cutting deck. Consult your tractor Operator's Manual for specific Deck Leveling and Deck Engagement adjustments pertaining to your specific model tractor.

(Uncut Strip - Riding Mower)

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jpollman said:

Thanks guys!

I'm still fighting this issue. I've been mowing pretty much every seven days. I cut my own lawn at about 2-1/2" and it looks pretty good. I took the machine down to my fathers place and cut his lawn. I have been cutting his at 3" all summer and it was pretty good but not as good as mine. The last cut on his, I cut it at 3-1/2" and it was terrible today. Very uneven cut! I only cut about half the lawn (it's about 1.75 acres) and had to leave. I'm going to go back tomorrow and step it down to 3" and recut what I did today and see what happens.

I'm thinking that the loss of vacuum seems logical because it does seem to get worse as the cutting height increases. I was using the original blades from when I bought the machine last year and been keeping them sharp. But a couple weeks ago, I went to another Gravely dealer and asked for a set of "mulching blades" for my ST-52HD and the ones he gave me appear to be the correct size. Although they were brand new, I did give them a few strokes with a nice sharp fine file to give them a very nice sharp edge.

I bought a mower jack and lifted it up when I installed the blades and made sure that they were all lined up when I was done. I don't know how long they stay that way once you start cutting, but I figured that was a good place to start. I also spent quite a bit of time the other day going through the deck leveling procedures and have a blade height gauge. I got it good and level left to right, and within specs for front to back. The manual says that the front of the blade should be about 1/8" lower than the back. It also says that if you "heel" the deck with the rear of the blades slightly lower than the front, it will use a little more engine power, but it can result in a cleaner cut. Maybe I'll try that next.

I'll let you know if and when I figure it out. Thanks again!

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djdicetn said:

I picked up a mulch kit for my Pro-Turn 152 this morning to deal with the clippings from a very mild/wet July/August here in middle TN that has made the grass grow very fast and very thick. It came with Gravely mulch blades and as I understand it Gator blades are not designed to be used with a mulch kit, rather with regular side discharge(I thought about that and still may give them a try). I too am toying with the idea of changing the pitch of my deck to have the rear blade tip lower(referred to in our Gravely manuals as "heeling the deck") but I only want to try one thing at a time. Iv'e bben very pleased with the OEM blades' cut with normal side discharge as far as cut quality, but the grass clippings have become a nuisance(I have mowed over them 4-6 times and made them barely noticeable). I hope the mulching kit will help mid season(when the grass is growing fast & thick) and will probably remove the mulch kit at the end of the season and go with the OEM blades or Gator blades with side discharge for Spring, early Summer and Fall cutting. I'll let you know what kind of results I have.

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jpollman said:

Hi folks!

I'm on my second season with my Gravely ZT-52HD. I bought the mulch kit for it and it worked fine last season. In the fall, I bought a set of Gator blades and it did a wonderful job mulching up the leaves in the yard. This season though, I'm having a problem with the deck not cutting cleanly. It is leaving a stripe of poorly cut grass that appears to line up with where the center and right hand blades cut. I've kept the blades sharp and one of them appeared to MAYBE be a little bent but it probably wasn't. Just in case, I bought a brand new set of mulching blades at my local Gravely dealer a couple weeks ago. Even brand new, I took a fine file and touched them up and made sure that they were good and sharp. It's still doing it!

I went through the procedure to level the deck side to side and set it to specs for front to back. It's still doing it! I bought a mower jack and raised up the front and climbed around underneath and there are NO signs of any blockages and the blades are all lined up and everything appears to be in order. I'm completely stumped!

My next plan of attack is to remove the mulching baffles and put the original blades back on it and cut the grass in discharge mode and see what happens.

Has anyone else had an issue like this and figured out what the problem was?

Thanks in advance for any input!

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Amm0622 said:

I have had the EXACT same problem with my two year old 452! Numerous complaints to Gravely and nothing has been done. They keep trying to tell me I'm the only one who has had this problem and keep making it sound like I don't know how to mow. It's extremely frustrating to have to mow properties twice to eliminate the uncut strip. Guys...the strip is the entire length of each and every pass. Gravely provided all the blades I have tried, so they're all brand new, I have paid to have them check and adjust the deck, and all I get in return is a "well, no one else has made this complaint so it's not an issue we've ever had." Long story short...selling this $11,000 heap and going back to the JD. Adios Gravely!

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