ZT52HD DECK VIBRATION FIX

[my87csx481]

My advice: do not buy without first trying it out. Fire it up, engage the blades. Make sure the noise is not objectionable to you. For some, ignorance and ear plugs are enough to achieve mechanical bliss. For others, that have seen smooth running belt drives (on motor vehicles and other machinery), it's painful to watch and listen to. The blade drive belt on mine has vibrated wildly from the first time I fired it up.

Update on the kit: part of the procedure involves installing washers (as shims) under all the idler pulleys. Then perform a belt alignment. I installed the washers exactly as described in the instructions (one flat washer under each pulley). This has raised the idlers high enough that the bottom lip of the pulley is contacting the belt/s (too much, in my opinion). But fired it up anyway. It seems to have helped at high speed. At idle, forget it. Much worse. But who runs their blades at idle?

As I mentioned, the contact amount is probably too much, and it is deflecting the belts axially. I am going to try to find thin flat washers to use as shims....to split the difference in hopes of a little axial contact will still dampen the harmonics.

Not a fix, in my opinion. My belts were not misaligned to begin with.

The instructions do not mention it but, I would think that you would want to adjust belt alignment with the deck at the height you use it at. And if you use it at extreme different heights, I guess use the middle position between the two, or where ever you use it most. I think deck height affects where the belt rides on the stationary idler pulley.

I need to try to find a replacement drive belt. Something kevlar reinforced. Maybe that will settle it down even more?

 

[cpurvis]

It surely makes me nervous to make the purchase seeing all the issues these fine folks have had with their units. Would the dealer be able to make that decision on replacement of the deck prior to Gravely's approval?

Only way to find out is to make the offer.

 

[Newcombe]

I will be contacting the dealer later this week and will make that offer. My87, I will engage the belts before purchasing for sure to check. You seem determined to fix this issue and I have confidence you will.
Did anybody's machine seem to get worse once things started to wear in to where everything is not as tight?

 

[my87csx481]

I haven't noticed anything getting worse.

If anything, things have gotten better (but I've made some minor mods along the way to make it better).

I've got about 35 or 38 hours on mine right now (can't remember.....maybe it's 35.8).

 

[my87csx481]

Aftermarket kevlar belt on the way. Not putting too much hope into this....but need to try it for my own sanity.

Kit update: The washers/shims in the kit are .075" thick. My pulleys were NOT out of alignment before the kit. But based on the .075" shims putting some axial pressure on the belt....I now have one .045" shim under the stationary idler pulley. Nothing under the other two pulleys. It's a little better than before the kit.

But the kits just attempt to "fix" the things that rattle. IMO, it's the belt's harmonics that are causing all the other parts to rattle. The "kits" do nothing to address the belt's harmonics.

IMO, Gravely should just supply washers for shims, and the discharge chute kit (which includes bolts and new bogie wheels). Not sure why they're sending new pulleys and arms. Seems rather expensive. The pulleys do nothing, nor do the arms....in they're current/identical-to-original configuration anyway.

Oh yeah, I still have my extra bushing on the large idler spring anchor too....to give it a bit more tension.

The saga continues....:confused2:

 

[cpurvis]

I noticed the drive belt whipping all over the place, too. It's kind of a weird arrangement in that the drive belt powers the center and left blades and a second belt connects the right blade to the center. We took the belt off the right spindle to see if that made a difference and on that mower, it did not. Going from memory here because it was last November that we did this. It went back to the Gravely dealer that week and has not been seen since.

 

[Newcombe]

I noticed the drive belt whipping all over the place, too. It's kind of a weird arrangement in that the drive belt powers the center and left blades and a second belt connects the right blade to the center. We took the belt off the right spindle to see if that made a difference and on that mower, it did not. Going from memory here because it was last November that we did this. It went back to the Gravely dealer that week and has not been seen since.

So Im happy to say that I picked up my new ZTHD52 yesterday and thankfully it does not have the dreaded vibration. My87, how did you make out with your aftermarket Kevlar belt, did it make any difference?

 

[cpurvis]

My friend was given a brand-new 60" Gravely loaner. He put about 60 hours on it and was offered it as a replacement but the 60" width just barely fit on his trailer and he didn't like the 'Gravely' brand engine.

Then they gave him a brand-new 52" replacement. He's put about 15 hours on it, says it has the same deck vibration problem as the original. I mowed with it for a few minutes and it seemed to me the noise was coming from the discharge chute. We took the discharge chute off and a huge amount of the noise went away.

Removing the discharge chute did not SOLVE the vibration problem. I can still feel it; he can't. It's cyclical in nature and anything 'loose' on the deck, such as the discharge chute was in this case, will rattle.

 

[Woody99]

I have a 52" that's making the vibration too. It's done it since day one.
Sometimes, it's perfectly quiet, but other times it just rattles really bad. It sure seems to be harmonic issues, and the dealer is working with the factory on it. We'll see how that works out.

Reason for the post is to ask a question or two.

I'm running aftermarket high lift and mulching blades. I've never had the factory blades on it, and wondering if the heavy aftermarket blades make a difference, adding to the problem?
Are most of you running stock blades?

Also, on the first set of blades (high lift) I had to balance them to perfection in order to keep from shaking things too much. They weren't off too much, but a good balance helped a little.

Something that I did, and would like to see if it helps anyone else, is I loosened the blades and moved them a quarter turn or so. It feels like it changed the harmonic point and reduced the vibrations to nearly an acceptable level.
I swapped those blades for a set of mulching blades, and the vibrations returned. I haven't tried yet rotating the blades because I don't think this is a real "fix" and want the dealer to hear and feel how much it shakes at times.

Another thing I found is some paint had been rubbed off on the bottom back side of the foot rest plate. There's a big bar that goes across the back, and on both the left and right sides the metal was bare. I put a couple of strips of heavy velcro on one side as a pad. It stopped the rubbing, but didn't do much for the noise.

Anyway, just sharing my experience and a couple of thoughts.

 

[my87csx481]

I didn't get notifications of the new activity (even though I signed in since the last notification).

The kevlar belts worked beautifully, for the first 5 or 10 minutes. Almost no belt vibration. I have about 5 or 6 hours on them now. Same old ring a ring a ring. Next step for me is figure out how to mount an additional idler pulley half way between the PTO and the deck (with pressure on the slack side only).

I am running the stock blades for the ZT HD, and also run a set of stock blades from a Pro-Turn 200/400. The 52" 200 has identical spindles to the 52" ZT HD. The Pro-Turn blades are a little bit thicker, and a little bit wider....so slightly more mass. All my blades are balanced using a Magna-Matic 1000 since before they ever touched grass. I found that the virgin blades were really close to balanced. Very suprised. Swapping blades between the two sets does nothing for my vibration.