ZT52HD DECK VIBRATION FIX

Another data point:

I mowed the other day, and set the deck down another quarter inch to 3.5". There was little to no noise or resonance. I'm not saying it's gone 100%, but it was a marked improvement from what it had been.

Reminder, the dealer installed the "kit" from the factory. It helped a little, but still had harmonics and resulting vibrations.
I repositioned the blades and as once before, moving the blades helped significantly.
When the dealer returned the mower after the kit was installed, I noticed they had it set to 3.25, which is lower than I normally mow, so I sat it up the 3.75 and never tried it at the lower setting.
Now it makes me wonder if the kit and adjustments were optimized for 3.25? Could be.

Anyway, kit installed, blades repositioned and set to 3.5 cut, the deck is really pretty quiet. Quiet enough that if it would have been like this from the beginning, I wouldn't have thought twice about it.
One more bit of information, the temperature dropped into the 70's from the 90's on the last mow too.

Woody99 said:

Another data point:

I mowed the other day, and set the deck down another quarter inch to 3.5". There was little to no noise or resonance. I'm not saying it's gone 100%, but it was a marked improvement from what it had been.

Reminder, the dealer installed the "kit" from the factory. It helped a little, but still had harmonics and resulting vibrations.
I repositioned the blades and as once before, moving the blades helped significantly.
When the dealer returned the mower after the kit was installed, I noticed they had it set to 3.25, which is lower than I normally mow, so I sat it up the 3.75 and never tried it at the lower setting.
Now it makes me wonder if the kit and adjustments were optimized for 3.25? Could be.

Anyway, kit installed, blades repositioned and set to 3.5 cut, the deck is really pretty quiet. Quiet enough that if it would have been like this from the beginning, I wouldn't have thought twice about it.
One more bit of information, the temperature dropped into the 70's from the 90's on the last mow too.

Click to expand...

Could you post a Picture of how you positioned the Blades.

DRG ZT HD 52 said:

Could you post a Picture of how you positioned the Blades.

Click to expand...

I just loosened the bolt on two of the blades, and rotated them ~90 degrees.
It doesn't really make sense to me why moving the blades makes any difference, but it has on the two separate occasions that I've done it.You would think that the initial install location would be totally random anyway.

I'll have to try it at a lower height, next time I mow (I might have one last cut for this season). I've kept mine at 4" from day one. When installing the kits, I set the pulley alignment with the deck at the 4" height.

When the machine was brand new, I set the 4" pin height with 4" blocks under the front blade edges, with taller blocks under the back edges to achieve the pitch described in the manual.

Dealer offered me a full refund. I took it.

I'll be purchasing something else in the spring. Most likely an Exmark (due to what's available within an hour's drive). Scag dealer is just too far away.

I have a couple Kawasaki air filters, and a couple kevlar belts that I posted for sale here: https://www.lawnmowerforum.com/showthread.php/57560-FS-BNIB-Kawasaki-air-filters-4-hours-used-kevlar-belts-for-Gravely-ZT-HD-52?p=347400#post347400

The filters fit FR and FS engines. The belts fit the ZT HD 52" deck.

Brand new to this forum. I have the exact same issues with my ZT. Did I miss a antivibration kit number? At Large did it resolve the issue or not

MJS10814 said:

Brand new to this forum. I have the exact same issues with my ZT. Did I miss a antivibration kit number? At Large did it resolve the issue or not

Click to expand...

This is what I found after the kit was installed, and it has been pretty good since then. Cold now, so no more mowing.
One thing I heard from the dealer is that the Gravely Tech Reps ask him if HE thought the problem was resolved. Issue is that he never thought that there was a problem to begin with, so the techs don't have the full story for their data.

Hello all. I have been following this thread for a few months, looking for ideas to help fix my Ariens Apex 52 (Gravely ZTHD52) which developed a horrendous rattle and vibration soon after purchase. Originally, I had planned to replace the tensioner spring with a fence turnbuckle to prevent the vibration which I believed to be caused by the spring, but I soon realized that when lifted and lowered the tensioner spring stretches too much for this to work. After some deliberation I tried removing the spring and stretching a bicycle tyre innertube over the spring to add resistance, like a car shock absorber, to hopefully reduce its vibration. This worked a little when tested but it seemed the rattle was still as bad as ever, even though the vibration had been reduced slightly. I studied the belt tracking and realized that the way the belt is routed, whenever the deck comes under any load the engine tries to pull the deck towards the back of the machine. The deck is mounted by four arms that would allow the deck to "swing" back and forth. To prevent this, they have installed two diagonal arms from the front of the deck to the frame. On the deck end of these arms there is a castellated nut threaded onto the arm which fixes through a mounting pin on the deck, this has a split pin through the nut to prevent it backing off. On my machine this nut hadn’t been tightened up all the way and the split pin had been installed leaving a gap, this was allowing the deck to move back and forth about a 1/4" so whenever the deck was running it shuddered back and forth. I tightened this nut up and reinstalled the split pin through the next hole and it was instantly noticeable that the deck felt much more solid even before starting the machine. During testing I found that the vibration has been reduced significantly and although there are still a few rattles from places like the belt access panel, the deck runs much more smoothly and seems to cut better. I hope this helps some of you to improve your machines, it has made a huge difference to mine. Perhaps you may want to give it a try. Good luck…

Thanks for posting.

In reality & good engineering practice that should be rubber mounted to damp out the vibrations.
I have noticed things like this when servicing bigger ZTRs.
I have a few Great Danes & their stabilizer bars have a rubber bush in the pivot end.
When new there is next to no deck vibrations or rattles but when work they make a hell of a racket.
The replacements were solid and they caused a lot of noise & belt dismounting so I got the old ones rebushed and they are back to new.
Decks will vibrate , they have no choice because it has 3 rotating blades and spindles which are not dynamically balance .
Plus the belt has a joint in it and every spring has a resonant frequency