Z326S Gear Box

ZD326S

Member
Aug 19, 2017
119
3
18
Owensburg, Indiana
I seen the recent discussion on Kubota Gear boxes but wanted to get my question answered promptly so started a new thread. My ZD326S machine is some 13 years old and just now started having trouble with the gear box leaking oil. Appears to be the bottom of the gearbox so I naturally suspect the bottom seal. I pulled the gearbox but the middle pulley doesn't just fall off like I seen one do on Youtube. I'm starting to think I need a puller to get the middle pulley off but don't want to damage anything! Thoughts? See pictures.

Also, once I get the pulley off do I need to disassemble the whole assembly to replace the bottom seal or can I get to it and replace it without disassembling the shaft and gears?

First time I have had to work on it.
I have an extra gearbox from my BX2230 but am told they are different animals.
Advice please! Thanks!
 

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lugbolt

Well-known member

Equipment
ZG127S-54
Oct 15, 2015
4,807
1,575
113
Mid, South, USA
2230 gearbox is different.

On the ZD box, you have to get the pulley off. If it slides off like some say it does, it's worn out and should be replaced-and it's key. It's supposed to be a light press fit, so you will need a puller that won't damage the pulley. I find it easier to remove the shaft from the box and change the seal that way. Real easy if you can figure out how. Remove cap, remove snap ring on center gear, drop the shaft out the bottom, R&R seal, reinstall shaft into box, install new snap ring. You will absolutely need a GOOD pair of snap ring pliers, not junk parts store crap either. Not all of them will fit in there as it's a tight fit.

As far as why the seal leaks? Check the shaft for a groove where the seal lip rides. OK? Proceed. Check the LOWER deck bearing, where the long shaft slides through it. Is the bearing ok? I always replace them. Next, is the bearing tight in the housing? It needs to be, if it falls out when snap ring is removed, the housing is junk. The lower bearing is ALL that supports that long shaft so it needs to be in excellent condition, or you'll eat another seal in short order. If all that's been addressed, the final issue is the gearbox vent. They tend to plug with dirt. Remove it & clean it. If the vent gets plugged up, it can't vent hot air out, which causes the seal to leak, the bottom one first by design and by gravity.

Finally make sure the mounting bolts go into the right holes. They are different side-to-side.
 

ZD326S

Member
Aug 19, 2017
119
3
18
Owensburg, Indiana
Thanks for the info lugbolt.
I was hoping you would chime in as I have took your advice in the past and find it very valuable.
Wow, I didn't know there was a vent, first time working on them.
So I do not have to remove the side to side pinion shaft?
I do see the clip ears on the middle shaft inside the gear box, just below the pinion bevel gear.
Seems pretty simple but I wasn't sure about the pulley, how to get it off without damage.
And I really do not want to disassemble the whole insides if I do not need to.
Thanks again.
 

ZD326S

Member
Aug 19, 2017
119
3
18
Owensburg, Indiana
I was able to get the Bevel Gear Shaft off by removing the snap ring but getting it back on was a little more tricky so I ended up removing the Pinion Shaft. It was easy to remove after removing the snap ring on the bolt side and punching the shaft and bearing out that way. I had to destroy both seals and replace them, still waiting on side seal since it wasn't in stock. All bearings seem to be in good shape and pretty snug after 12 years of hard use.
 

ZD326S

Member
Aug 19, 2017
119
3
18
Owensburg, Indiana
Since replacing both seals in the ZD326S gear box..... the first time I ran the mower it was without incident, everything looked good. When we use the mower it takes 3.5-4 hours to mow our property each week.
But today I used it again and this 2nd time seems to be barely seeping and I mean very light. The grass clippings at the very base of the gear box was barely oily. I cleaned the vent before the first mowin after the seal replacement and wonder now if I should just replace the vent? I did not replace any bearings or the shaft and the thing runs as normal, no wird noises. Any thoughts?
I sure do not want to keep pouring money into repairs if the problem keeps showing up.
 

ZD326S

Member
Aug 19, 2017
119
3
18
Owensburg, Indiana
After pouring $300 in parts and 2 teardowns I have the same result....leaking gearbox. 1st teardown I replaced the seals only, 2nd teardown the 2 seals and middle shaft. When I put it all back together everything seemed good and tight. With it leaking on the bottom seal with the middle pulley pressed against it, who knows what is going on with it. Not sure if there is any other options besides buying a totally new gearbox or new mowing deck. :confused:
 

lugbolt

Well-known member

Equipment
ZG127S-54
Oct 15, 2015
4,807
1,575
113
Mid, South, USA
Is the lower bearing in the deck spindle loose? I mean loose AT ALL? If so, that's your cause. The bearing itself can wear out OR the aluminum spindle housing can wear out and the bearing get to flopping around in the housing. That's all that supports the long end of the gearbox shaft, so if it gets loose, the shaft wobbles around and takes out the seal. Also look at the lower bearing in the gearbox; if it's loose in it's bore, it too will eat seals. If that bearing is loose in the bore, you will have to replace the gearbox housing. That is not common, though--but worth looking into. The pulley can cause problems, worn blades can cause problems (balance issue) as well as binding PTO shafts (spline lack of grease on the sliding joint) and U-joints and big nicks in the belt or junk in a pulley can cause vibration too.

Just blow the vent out, should be fine.
 

ZD326S

Member
Aug 19, 2017
119
3
18
Owensburg, Indiana
Thanks lugbolt!
I suspect you are correct because it takes 1 1/2 - 2 hours for the leak to show up. The bearing in the lower gear box seems tight enough....I can push it out by hand but it takes some force. I cleaned the vent but it is hard to tell if it is clogged internally...the plunger seems okay. I will look it over again before buying a new gear box. I tried to find a rebuild kit for these boxes thought that may save $$ instesd of buying individual pieces. The play in the blade after reinstall seemed tight with no play but I guess maybe it doesn't take much play.
 

ZD326S

Member
Aug 19, 2017
119
3
18
Owensburg, Indiana
Well 3rd time tearing it a part and bad news, there is a lot of sludge.
When underneath the mower removing the blade, clip, and geared washer the protruding shaft seemed solid with no play.... but when I removed the gearbox from the deck there was a lot of play.
Once the drive shaft and gear was removed, I then removed the center shaft. Now the center middle bearing will fall out of the housing when turned upside down.
When I inspected this middle bearing with the pressed gear, the gear is solid in the bearing but it seems the slop is in the bearing itself where I can see the ball bearings move side to side so the center moves with it. I suppose I will be ordering a new gear box $$$$:(. Unless anyone has a suggestion.
The lower mower deck bearing appears to be solid and in good shape.
 

ZD326S

Member
Aug 19, 2017
119
3
18
Owensburg, Indiana
Thanks Dave.....I will give it some thought...hate to spend any more $$$ for parts for a possible temporary fix. These shims concern me in these gear boxes because no doubt they were used to take play out of the whole system and when you go to replacing parts you no longer have the same system.
 

Digger Dager

Member
Lifetime Member

Equipment
M59 TLB, B3200 w/front snow blower, 3 @ ZD326 62" rear discharge mowers
ZD326S,

Last fall, we bought a used ZD326R. Previous owner did not maintain it very well, and it appeared to have been stored outside. Come to find out the mower gear box was dry. Like your's, the bottom seal was leaking. I took it apart to see what would be needed.

After looking at the parts, and the cost of those parts (thanks to Messick's), I ordered the whole gearbox and the bearings in the spindle housing. With the time involved to tear-down and rebuild, it made more sense to replace the whole thing. Ordered from our dealer and had all the parts within a week.

Everything looks to be straight and true, but I will be keeping an I on it for the next several months of mowing.

Digger
 

ZD326S

Member
Aug 19, 2017
119
3
18
Owensburg, Indiana
Yes, I already have ~$300 wrapped in parts and have gotten no where. I priced a new gearbox and it was over $900 from dealer and I assume the new unit would include a new center pulley.
As I said, I would have liked to rebuild it for less $$ but replacing the parts and not knowing what shims are needed to tweek the system, I am of the mind it would always be a battle. Will never know for certain, but I wonder how successful these rebuilds actually are, and if successfu,l how long the rebuild will last.
I did purchase a used ZD326S with only 500 hours, so now I am not so stressed and can take my time working on the gear box. I bought this new used one because I am sold on them. The one I am working on has almost 1100 hours and lasted ~12 years. Besides this gear box problem the only other problem, I had to replace the main seal in the back of the engine. Pretty dependable.
 

ZD326S

Member
Aug 19, 2017
119
3
18
Owensburg, Indiana
The problem turns out the bottom bearing (geared) broke down and wobbles side to side. The bearing doesn’t wobble in the housing but the inner diameter of the bearing wobbles. So my new bearing fits in fine with no play sideways but there is movement up and down in the housing. I know there is a clip on the center shaft going thru the geared center bearing to restrain up and down movement. So is this by design or do I need retaining compound on the bearing? What would cause the bearing to breakdown?
 

whitetiger

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Equipment
Kubota tech..BX2370, RCK60, B7100HST, RTV900 w plow, Ford 1100 FWA
Nov 20, 2011
2,542
1,059
113
Kansas City, KS
The problem turns out the bottom bearing (geared) broke down and wobbles side to side. The bearing doesn’t wobble in the housing but the inner diameter of the bearing wobbles. So my new bearing fits in fine with no play sideways but there is movement up and down in the housing. I know there is a clip on the center shaft going thru the geared center bearing to restrain up and down movement. So is this by design or do I need retaining compound on the bearing? What would cause the bearing to breakdown?
It is by design, do not put anything on the bearing trying to anchor it.
 

ZD326S

Member
Aug 19, 2017
119
3
18
Owensburg, Indiana
Thanks whitetiger! I talked with a Kubota mechanic yesterday that told me the same thing. I was under the impression that the bearings had to be nailed down and stationary. But he explained that the clips on the top and bottom of the center shaft keep it in place. Just curious why the old bearing came apart like it did. It's a learning process...this is my third time taking it apart and putting it back together. If this is successful I have spent ~$500 and saved ~$450.
 

ZD326S

Member
Aug 19, 2017
119
3
18
Owensburg, Indiana
Success! No leaks! New Shaft, Gears,Seals,all Bearings, and key way! Gear box is dry. These ZD326S are good machines this one is 12 years old and we mow 10 acres a week approximately. Turns out the bearing in bottom gear box housing broke down and the bottom seal started leaking. $500 in parts and should last a long time. Went out and bought a used one with low hours so should be set now. Was told the new ones have so much emissions sensors and are a pain so better hold on to old ones. Thanks for the help and input!
 
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