Shuddering on left side of Z724 zero turn

[jetfisher]

Hi - long time browser of this forum but first post... I searched and can't find my exact issue.

I had a GR tractor for 14 years, virtually no issues. Sold that and now I have a Z724 zero-turn bought new August 2022 ( Z724XKW-3-54). Not too many mows in (maybe 5 hours), it started shuddering/hesitating/loss of power on the left side... progressively got worse to the point I couldn't mow. This happens when I have PTO engaged and going up the slightest of inclines. I don't mow any big hills or have any rough terrain. Long story short, it has been in the dealer shop 3+ times since then for the same exact issue on left side (right side has always been fine). Dealer has replaced left transaxle twice (maybe 3X now, I lost track). The issue just started showing up again (started losing power left side April 2024 after the first couple mows of the season and full shuddering mode May 2024). Only 39 hours on the engine right now.

I called Kubota first this time and it was useless, they said I have to go through the dealer but could document my story. OK. I called my dealer and they are picking the mower up again tomorrow. It's been in the shop more days during mowing season than I've had it.

So my question is twofold - 1: Could it be something different than the transaxle that the dealer is missing? 2: Any tips on where to go from here - I feel like I'm the definition of insanity trying the same thing again and again expecting different results. Corporate Kubota had no answer when I asked if I could get a replacement since this was clearly a lemon, dealer says I may be able to do a trade in for a different model... but I'm guessing I will pay. Is there another phone number for corporate to get better results, or should I be more of a squeaky wheel to the dealer demanding a new mower free of charge? Any other tips?

Much appreciated

 

[Mowbizz]

No answer for you but good luck from Z422 owner…

 

[GreensvilleJay]

curious, so I looked at the parts drawings

1) there's a different unit based on machine serial number, so check invoice part number vs your machine.

2) maybe the brake or parking brake is partially on ?

There HAS to be a real problem since dealer replace 2-3X and it's STILL not working properly. I don't have one but simple(?) test is raise rear of unit off ground and see if you can easily spin the tires. Compare left vs right.

Mechanically it's simple system. HST-->wheel + brakes. Only FOUR things to deal with.

 

[jetfisher]

Thanks guys, I will do the test to see tire spin. But going downhill w/ PTO engaged it does fine, but slightest uphill is when left side shudders. This seems to be independent of whether I'm actually cutting grass or not. One other thread on this forum I saw discussed an issue with the wheel slipping inside the tire which got me thinking... maybe that's another test I could do - a video of the left side wheel when I'm mowing uphill. Not sure how likely this is the problem though.

I will check the invoice part #, that's a good call. I didn't mention, but dealer performed the replacements of transaxle under warranty, and they were kind enough to send me the tickets so I should be able to make this comparison.

I will also ask dealer about the parking brake - I haven't noticed any issues with the brake but worth an ask.

I'm also wondering if Kubota simply has a quality issue with the transaxle... the dealer seems to think this is likely the cause. But I would think this would be a more widespread issue on other mowers if this were the case. Extensive forum and google searches, I really can't find anything.

I've got my fingers crossed that this time it will be fixed. Running out of fingers to cross

 

[dirtydeed]

when you say they have replaced the transaxle did they actually replace the entire pump?

 

[jetfisher]

Here is the part # from the invoice, not sure if that includes the entire pump?

 

[jetfisher]

curious, so I looked at the parts drawings

1) there's a different unit based on machine serial number, so check invoice part number vs your machine.

2) maybe the brake or parking brake is partially on ?

There HAS to be a real problem since dealer replace 2-3X and it's STILL not working properly. I don't have one but simple(?) test is raise rear of unit off ground and see if you can easily spin the tires. Compare left vs right.

Mechanically it's simple system. HST-->wheel + brakes. Only FOUR things to deal with.

Is the below what you mean with different unit based on serial number, is "<=80676" serial numbers less than 80676? I'm not seeing this number correlate with my serial number, I only have 4 digits at the end of mine? Sorry, I'm a noob.

The snip below is from Kubota but I saw on Messicks they have replaced K3811-10030 with a new #, wondering if this means potentially Kubota fixed the issue? If so why wouldn't Kubota part list have this new part. I have a lot to learn...

 

[GreensvilleJay]

They replaced the entire 'assembly' , the HST unit. Highly unlikely any dealer would rebuild an HST. Same as a lot of car tranny shops, they're 'swap shops'.

 

[mikester]

I'd have hoped K learned from their ZD28 HST issues and designed out the problems by now.

 

[GreensvilleJay]

Why I suggested 'brakes or linkage drag issues' is that the RH side HST assy is essentially the SAME unit.
It'd be interesting to have examined the 2-3-4 ? LH units to see WHAT the failure was, but I'm still leaning towards an external problem.
Be nice to know WHO made the HST units, model, etc. and have Goggle invesetagate !

 

[lugbolt]

I'd have hoped K learned from their ZD28 HST issues and designed out the problems by now.

kubota buys the HST's for the Z7, Z4xx, Z1xx series mowers. Z7xx series mowers use Parker HST's, most of the rest of them are build by HydroGear.

the ZG2xx series, ZG3xx series, and the ZD series are kubota built (mostly) and fully serviceable.

The parkers did have some issues and they've supposedly improved them. But nobody can say what was improved.

also, belt slip can cause "chattering" as well. Oftentimes on the zero turn mowers, one HST drive pulley will have more belt wrap than the other, and if there is any moisture, the one with the least wrap will slip before the other one will, which makes you think that the HST on that side is failing. Also a potential cause is a pulley that is too wide and the belt riding at the bottom of it, slipping. Or a slipping crankshaft pulley (they forget to put the key in??) Or more frequently because of the design, the freewheel lever being halfway in the freewheel position. On the Z7 series, this was somewhat common because of where the levers are located. Reach under there and move the levers all the way toward the "tow" position, then all the way to the "run" position and try again. Hopefully that's all it is.

 

[GreensvilleJay]

The sad thing is that the dealer's mechanics have replace the HST 2-3 times,for the same problem ! Someone there should have said 'what,this again ??!!!' (it's in the computer..).

LB suggests several possibles and I'll add 'maybe a bad/worn/oily belt' ?

 

[lynnmor]

I have a different brand of zero turn but it uses the Hydro Gear transmissions. I have snapped the transmission mounting bolts several times and found them loose as well. Contacting the company resulted in the usual "no one else has that problem." You might want to check the mounting hardware and frame for issues, my opinion is that these transmissions have inadequate support.

 

[whitetiger]

Thanks guys, I will do the test to see tire spin. But going downhill w/ PTO engaged it does fine, but slightest uphill is when left side shudders. This seems to be independent of whether I'm actually cutting grass or not. One other thread on this forum I saw discussed an issue with the wheel slipping inside the tire which got me thinking... maybe that's another test I could do - a video of the left side wheel when I'm mowing uphill. Not sure how likely this is the problem though.
It is very likely and somewhat common. Take a paint marker and place a reference mark on the tire in line with the valve stem. Mow for a while and see if the mark is lined up or not.

I will check the invoice part #, that's a good call. I didn't mention, but dealer performed the replacements of transaxle under warranty, and they were kind enough to send me the tickets so I should be able to make this comparison.

I will also ask dealer about the parking brake - I haven't noticed any issues with the brake but worth an ask.

I'm also wondering if Kubota simply has a quality issue with the transaxle...
The transaxle is mass-produced by Parker or Hydrogear and is purchased by Kubota. There is nothing special about the unit for Kubota.


the dealer seems to think this is likely the cause. But I would think this would be a more widespread issue on other mowers if this were the case. Extensive forum and google searches, I really can't find anything.
This exact transaxle is used by dozens of manufacturers in zero-turn mowers, mud buggies, powered lawn carts, the list goes on.

I've got my fingers crossed that this time it will be fixed. Running out of fingers to cross

I would concentrate on the belt or the tire slipping on the rim.

 

[John D 2]

The fact that the dealer keeps replacing parts and it keeps happening confirms that something is wrong. I think after 3+ attempts I'd be sitting down with the manager and requesting that Kubota just replace the unit.

You might also contact the local news station and ask for their help. . .

You would be amazed how much more Corporations are willing to work with the customer to resolve an issue when a camera is on.

Good luck.

 

[lugbolt]

I have a different brand of zero turn but it uses the Hydro Gear transmissions. I have snapped the transmission mounting bolts several times and found them loose as well. Contacting the company resulted in the usual "no one else has that problem." You might want to check the mounting hardware and frame for issues, my opinion is that these transmissions have inadequate support.

Hustler??

 

[lugbolt]

The fact that the dealer keeps replacing parts and it keeps happening confirms that something is wrong. I think after 3+ attempts I'd be sitting down with the manager and requesting that Kubota just replace the unit.

You might also contact the local news station and ask for their help. . .

You would be amazed how much more Corporations are willing to work with the customer to resolve an issue when a camera is on.

Good luck.

I have done dealer work for decades, mostly kubota but I'm done with them as of 2020

what I learned is that dealers don't replace equipment, they fix them. UNLESS Kubota agrees to replace it, which is extremely rare. I have heard of it, but out of tens of thousands of units come through the dealer, I've never "seen" it. Wait, yes I did-L3301, had a flywheel problem but nobody could figure it out so kubota agreed to swap the tractor with a new one, I had to fix the original and then kubota took it to the training center for a school tractor (for us techs to learn on).

with that said, dealers are not all equal. Kubota offers incentives to dealers that have certain credentials, such as better warranty reimbursement and more likely to help with goodwills, for dealers that are "elite" certified. Getting that certification is NOT easy, and maintaining it isn't either. There are a lot of non-elite dealers out there. While I will agree that becoming elite certified gives the dealer a set of incentives, I will also go out on a limb here saying that these certifications can HURT the customer should they lose that cert, or if they just can't achieve it to begin with. So it makes me wonder if your dealer isn't elite certified? I don't know. IF they are, they'll need to be in contact with tech support to get them to step in. Oftentimes that'll also mean that the division service guy may have to show up. This stuff can take time.

 

[lynnmor]

Hustler??

Country Clipper
Challenger

 

[Lug66]

Do you know if they replaced the pulley on the left transmission or was it reused? A hairline crack can open up under a load like climbing a hill, but have no effect on a decent or level ground, causing the belt to lose its friction.

 

[jetfisher]

Thanks for all the input guys. I just got word that the dealer has a new transaxle arriving from Kubota this Monday, and the dealer will install and deliver the mower back to me. I asked what the part # is, he said K3811-10032. Interesting. The original P/N was K3811-10030 and both times the transaxle was replaced previously was with K3811-10030. As I mentioned above, Messicks showed that K3811-10030 was replaced with K3811-10032. But Kubota still showed K3811-10030 on their parts drawing.

After Lugbolt said that Z7XX uses Parker transmissions, I got to thinking, and here's my theory:

Parker realized there was an issue with K3811-10030 and fixed the issue resulting in K3811-10032 being the replacement. This was made available by Parker, but Kubota either had an existing stock of K3811-10030 they had to burn through, or had to go through their own red tape to implement K3811-10032 so there was a delay in sending the updated P/N to dealers. Maybe Kubota had hopes that the issue wasn't 100% of the units and that by continuing to replace problem mowers with K3811-10030 that a good unit would show up. Guess what - now the Kubota drawing shows K3811-10032:

So at least now I have hope that the issue will be fixed, I will see probably in about a month after several mows if the mower is still running well. If not, well then I've got a lot of great advice from you guys, so thanks! I'll start with checking tire slip and belt issues as you guys mentioned.

The crappy part is that I've had to pay for someone to mow my lawn many times the past 2 years while my new mower was in the shop. Also really tarnished my opinion of Kubota overall - I still can't believe there's no support if you call Kubota corporate. But if this fix sticks, I can move on. Cheers!