Z121S woes

[Seth]

Every month that goes by finds me less and less thrilled with this machine. That latest is a broken drive belt. After an inspection, it appears that the way to get this belt changed is to get the gas tank out of it, which appears to be quite a chore. Is this correct?
Background; Yesterday I was mowing, and I swirled around, and ran over a rock. A big one, about the size of your head. The tire went over it, and the deck landed on it, stalling out the machine. It appears the machine suffered no injury at that moment, but les than 15 minutes later, I got an awful squealing, and a burned rubber stink, and the drive belt broke. NOT the deck belt, the one to the trans. So, I have to think these 2 things are related. I'm really hoping that the trans is ok.
On a related note; While moving the machine to the garage, I went to put it in freewheel mode. On the LH side, there are 2 holes, one for drive, the other for freewheel. On the RH side, only 1 hole, for drive. Had to bungee the hook into the freewheel position to keep it in freewheel. Is Kubota really that lacking in their quality control, or am I missing something?

 

[Roadworthy]

I obviously can't see your machine but from your description it sounds like you did more damage than you realize. You may have bent something else under your mower - or it could be a coincidence. In my experience damage to the deck is usually limited to the deck. Check it out fully for binding on the drive pulleys when you get it apart. As far as replacing the belt, you'll probably find instructions in the manual.

 

[whitetiger]

The hydro belt is easily replaceable from underneath.

 

[Seth]

Hmm, I can't find the manual. But it looked nearly impossible. Lying under it, I couldn't even really see where the belt would track.

While those 2 events sure are a coincidence, I'm wondering how something could have fed back through the deck, and ruined the drive belt. The deck appears fine. It ran fine and cut fine after I hit the rock. Wasn't even vibrating. Odd...

 

[lugbolt]

the extra hole is easy to drill just make sure to get it in the right spot, and touch up the hole. I asked a japanese engineer why they didn't put the other hole there. The enginerd had no answer. Not japanese and not in Engrish. There was no answer other than "I dunno no hole". An American Engineer-who was the lead designer of the ZG100 series (predecessor to the Z100 series) agreed that it needs to have a hole, but had no answer why the bean counters didn't want it there (his words not mine). Just drill one and be done with it, if you have a drill and a 1/4" bit. If not borrow one. If you can't borrow one and you're close to me I'll do it. Free. I agree, it should be there but for some reason (that is not known) it is not there. If I know someone who has an issue with it, I just drill it for them. I did it on mine too.

The belt. Oh gosh hst belts. If I had a dime for every Z100 series HST belt I replaced I'd be very very rich. Initially there were some issues with the system. They lined most of them out. Then in 2019 they had another "fix" which is a permanent fix. They (Kubota) was paying for dealers to install a debris guard on the deck which helps keep junk from being shot up into the HST belt. Also, they were replacing the HST pulleys with wider ones, which helped keep the belt on. Additionally an idler that had a deeper groove. The combination FIXED the Z100 mowers. If it were me (and it's not obviously) I'd call the closest dealer and ask them if the Z100 frequently failing HST belt fix-as-fail bulletin is still active. If so, I'd highly suggest telling them that this it the third or fourth or fifth time the belt has come off and you've been putting it back on yourself. At that point, if the bulletin is still active, let them fix it once and for all. It may have only been a one-year deal. I left Kubota dealer in Oct 2020, so I don't know. Call and ask them.

If you don't want to let kubota pay for it, or if the bulletin is not active, the best way to get to it is from underneath. FIRST THING IS SAFETY (REMOVE KEY AND SET THE PARKING BRAKE). Jack up the mower, the higher the better. If you can get all 4 wheels up off the ground a foot it's better than doing it with them ON the ground. Remove the pto clutch limiter, disconnect pto clutch wire connector, remove the belt guard, remove the idler guard, remove idler tension spring. Install the new belt. Make sure all of the junk is out of the pulleys (all 4 of them, especially the engine pulley!!). When putting the belt on, don't put it on the engine pulley just wrap it around the shaft below the pulley. Now install the spring and the idler guard. Using a 14mm wrench, turn the crankshaft while putting the belt into the groove of the engine pulley, walk it on. It will go about halfway and pop in the rest of the way on it's own. This is why it's important to remove the key. One of my coworkers didn't and left it on, and while walking the belt into the pulley the mower started and liked to ripped his hand off. He was really lucky!

No don't take the tank out, although it's not all that bad to do, it's easier to do it from the bottom. With the tank out you still can't get to the engine pulley and both idlers from the top. May as well leave it in, and do it all from the bottom.

I do them in about 30 minutes, sometimes less depending on a lot of things. But 30 min is pretty typical for someone who's done a couple. IIRC flat rate is 0.4 hours (24 min) which I think is ridiculous but that's normal with any warranty job, they never really pay enough.

I hate that people have issues out of these things. I mean they really are a sweet little residential mower. I own one and it has been problem free other than a loose nut and bolt here and there (mine is a 1st generation, ZG127S-54). The 1st gens didn't have lock nuts on a few linkages, rather a regular flange nut which comes loose from time to time. Never a belt. Previous owner put about 2 dozen belts on it and one afternoon after work I went to her house and watched her mow. No wonder. She used it for a bush hog, a rock crusher, a bulldozer, and a forestry mulcher. VERY hard on it. I had to school her about using a screwdriver to hammer in a nail; wrong tool for what she needed done. Once I made some suggestions, she never had another belt problem, neither have I (yet). Love the little mower even with it's imperfections.

 

[mikester]

I've thrown away a lot of hammers...POS defective hammers keep missing the nails and hitting my fingers.

 

[Seth]

Lots of good info, Lugbolt, thanks.

Though, it's already at the dealer, and I have a piece of info for you. Seems that hole is not there on purpose. I was told by a mechanic at the dealer that there are a lot of Kubota machines like this. In the case of a tractor that has only 1 disconnect rod, it has no hole at all. You must by design hold it in the freewheel position. So it's apparently a safety thing.They don't want you locking it completely on freewheel and have it get away from you. I asked the mechanic how in the hell you're supposed to hold the rod in the freewheel position, and push the damn thing. He didn't know.
Thanks for the offer, but I have the tools and know-how to make a hole. But I think I'm going to leave it. I hate rust more, and I have some little rubber straps that will hold it where I need it.
The service woman seemed genuinely interested to hear my laundry list of complaints. That was nice. So, I told her. She agreed that this should not be on a premium machine.

 

[lugbolt]

well really the Z121 isn't a premium machine. It's the lowest of the Kubota residential zero turns. Wait, the Z122R was (now the Z231). Sorry about that. Premium would be powered by diesel. In other words, ZD1511/ZD1211/etc. Or smaller gas burner ZG222/ZG227.

It was originally designed to be a high profit mower to compete with Deere's offerings of roughly the same power/deck/features-and it destroys deere. And bad boy. Exmark--and many others. The biggest problem with the ZG100 and Z100's was that they were rushed to the market, and built as "cheap" as possible. Look closely and you will see many of the same bolts holding the entire machine together--that is one of many ways they reduced build cost.

Nonetheless, it's a great machine and Kubota will stand behind them.

 

[Seth]

I consider anything with Kubota orange paint on it to be "premium". It certainly has a premium price...

I do like it. It's just that it has a bunch of mostly small things about it that drive me nuts. From day 1, one of the front tires hasn't held air. The anti-scalp wheels don't swivel, and regularly dig into the lawn. It hasn't gone in a straight line since day one. (Has been adjusted by the dealer twice, though.) Lawn clippings and dirt settle in the bottom of the gas tank and starve it, requiring a tank clean out. A bolt in front of one of the rear wheels sheared off. (Dealer replaced it and wanted to charge a hundred bucks for that. I told them no way) That missing hole on the RH freewheel control. They can't be bothered to paint their replacement parts consistently, or to send you 2 that match.

But I like it. I like the way it looks. It runs good, starts right up after sitting all winter. It cuts nice. Battery, fuel, air and oil filters easily accessible. Good setup on the gas & hydro oil fills. Goes up steep hills like nobody's business. Deck adjustment is easy and pretty convenient. Seat is pretty comfortable.

Would I buy another? IDK. I would certainly NOT by JD. Nor anything sold buy HD, Lowes, TS, etc. Exmark? Maybe. But I don't like the (very) local dealer's repair shop. Can I afford one of the even more premium brands? No. So, not sure where else I'd go. Kubota it is.

 

[lugbolt]

On the deck wheels are they adjusted correctly? They should never be in constant contact with the ground, rather should be approx 1/4 to 1/2" off the ground. They are anti-scalp rollers and nothing more. Thats why they don't have pivoting casters like the diesels do. On the little Z100's, if you run them on the ground constantly, a few things WILL happen. First the wheels and bolts (axles) are going to wear out, quickly. Secondly, it puts more strain on the rear deck hangers which makes them crack/break. Thirdly, the cut quality suffers. There is a sticker on the side of the deck that outlines how to adjust them.

Junk in the tank isn't a Kubota problem. I am sorry to be the bearer of bad news there. There is an easy way to get the junk out but a lot of techs (and owners) don't have one. Fluid evacuator. Stick the tube down in the tank, suck the junk out. Problem solved, well, as long as you can see it and get to it. Some mowers it's impossible. ZG222/ZG227 comes to mind. Prevention is key here. Use a screened funnel, clean the filler area before you add fuel, etc. Oh and don't leave the gas cap off for any length of time. (Guilty!!) It almsot sounds like you still have the old style pickup tube. The new style has a screen on it and it doesn't plug up unless there is so much junk in the tank that it completely covers that little screen (I haven't seen it). There was a big campaign which, of many other things, addressed this. That campaign (some called it a recall but it wasn't a recall) is now expired. It was active from Jan 2018 through Jan 31 2020. You might ask the dealer if they can address that, Kubota might pick up the tab on it. It is, a problem solver for sure!

Front tires. Yeah that was always a complaint. Briers and sometimes stickerweed will make tiny microscopic holes in them and they will leak down Most brands use the same tires. Bad Boy used them too and they too had issues with them. Grasshopper offered "tweels" which were nice but high $$$. Some guys foam filled them but that makes em real heavy. Put some PCC in them. Slime? Never had any luck with slime, only PCC. Google it, it's good stuff. Secondly on those little tires most folks put like 5-10 lb of air in them and they will keep leaking down at that, and will come off the rim. 20 psi is what the book calls for I think, and is what I run mine at-and ever since I started inflating properly, they hold air, like forever. And there's no PCC in the front tires, only in the rears (on mine). They were down 1 psi over the winter. I keep them checked, tire pressures play a HUGE role in cut quality.

Tracking on any zero turn. Another issue, among ALL brands of ZT's. You can set the tracking to be 100% straight on flat concrete but on a yard, that has many little humps bumps, slight inclilnes, you are always gonna have to correct, they never (ever) will go straight on a yard. That is something to get used to with any ZT until they start putting GPS on them. Hmm--idea! Best advice I can give to go straight is to pick a reference point, whether it be a tree, house, fence post, pine cone whatever, and make your first pass straight to it. From there, you can correct if need be.

 

[Seth]

Yeah, the anti scalp wheels don't ride on the lawn, at least all the time. I've adjusted them up from factory once, and will probably go one hole further.

Actually, I do know someone with a fluid evacuator. Next time it happens, I will be taking care of it myself.

When it comes back, I'll give the tire pressure another relook.

And when I said it doesn't go oin a straight line, I meant on pavement. When cutting, it's not nearly as noticeable. Fortunately, the adjustment is obvious and easy. I suppose in general, I will have to be doing more for myself on this thing.