I have an older ZD25, but with only about 550 hours. I am having early stage pump failure. Apparently Kubota did a "silent recall" - no notification of consumers, pay part of repairs only for those that complain loudly. But there is a recall "kit" - about $4000 parts and labor to fix one side. Local dealer has been particularly unhelpful. Kubot generally makes a good product, I think, but their customer relations leave a lot to be desired.
There was no silent recall.
There was a fix-as-fail bulletin, and Kubota extended the factory warranty from 2 years to, as I recall, FIVE on the transmission only. Fix-as-fail means that if an HST failed within that 5 year period, Kubota would help the owner with the repair costs. But if it was working properly, nothing was to be done-that is why it was a fix-as-fail only, and not a recall.
FYI, a "recall" is typically safety related, in other words, if the vehicle in question has a defect that can be directly related to operator, passenger or bystander injury, a recall can be issued. This goes for all manufacturers that I am aware of, including motor vehicles (cars, motorcycles, etc).
The fix for the problem is to service the HST more often than the manual specifies. Every 150-200 hours, a little more often if used extensively in hotter climates. The "kit" that was offered for them included another reservoir, that increased the fluid capacity hence helped the HST run a little cooler.
Another HST failure point is real simple, yet real complicated. The two dampeners on the control arms, they function in slowing down the rate at which the arms can be moved forward and backward. This does several things, one being that it makes it a little smoother in it's operation, more comfortable per say. But they wear out over time. When worn, the dampeners don't dampen movement as much and the control arms can be moved pretty quickly, which puts more strain on the HST's, and more heat into the fluid, both of which contribute to early failure. How much pressure is put on an HST when under pressure? The HST high pressure relief is around 5000 lbs. There are 5 pistons in the motor, each about 3/4" in diameter. At high relief, there is nearly 18,500 lbs of force pushing the motor away from the swash plate-in other words pushing the HST itself apart. That's why the dampers are there-to help reduce that internal pressure as the operator moves the arms forward or backward. I have seen some bad boy and others that didn't have the dampers, or were removed/worn out, that actually completely split the HST case open from an operator going full speed backwards, then moving the arms forwards fully to pull a wheelie, or jump a curb, or whatever. They make a BIG bang when they break too.
It is my understanding that the 326/331 and the early ZD's had nearly the same HST's. But the ZD300 series center case held more oil, has TWO filters, and a larger charge pump. They did not suffer the same problems as the early units, mostly due to more fluid capacity. Kubota learned of this AFTER the ZD300's were in testing, hence why the "kit" was introduced to "fix" the early 25's and 28's. I'm not a kubota engineer, just a dummy bystander who watches what goes on behind the scenes as best I can-hence I said "it is my understanding". I may be partially or totally incorrect. A dealer or Kubota themselves would be a better source for the correct info.
It is also my understanding that the "problem" is more pronounced with units that are used in hotter climates, serviced less frequently, and/or commercially used. I do know from my own experience that commercial guys don't maintain them nearly as often as really should be (I were one of those commercial guys-and can speak firsthand). One problem there is the hired hands could care less about the equipment as they aren't having to pay for it. They just run the daylights out of them, go home for a few hours and come back next morning to do the same thing. When the hint of a problem was showing it's ugly head, screw it, it ain't theirs, run it until it's completely dead and then tell the boss. We had 3 back up units for this reason; they were "retired" mowers that were patched together to get by for a day or two while another one might be down. This sure made things go a LOT smoother in our business.
If the grass was/is a bit high the F would beat the Z if quality of cut is measured. The F will cut high grass fairly well at semi fast speed and I doubt the Z would. I believe the Z would require two passes to do the same job an F would do on high grass in one pass. No proof, just speculation from lots of F experience an a test run on a Z, your old Z. Having mowed the same grass on both models you should be the expert as to this comparison. Maybe you can do a comparison story based on actual experience.:thumbsup:
