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Old 07-29-2010, 06:45 PM   #1
jptbow
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Default zd28 trans problem

i have a zd28 that the left wheel will barely move. I've read that there are problems with pumps or something with these. Is there anything that I can check or do to test this or figure out the problem for sure. I've looked and the rods going to the pump are moving the same....the left and the right. the right works correctly but the left hardly has any response at all. Also is there somewhere that I could download a service manual for this for free?
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Old 07-29-2010, 08:21 PM   #2
Service Dept Vic
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Default Re: zd28 trans problem

If that service complaint landed in my shop, I'd start by making sure that the brake is free on that side and not hung up.

If the brake pedal cross shaft or adjuster linkage is siezing or has allready siezed it will maintain the brake on the siezed side.

I'd recommend buying a complete set of manuals for that mower, especially if it's new to you. The WSM, an operators manual as well as the Master Parts and Factory Assembly Order Manual.
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Last edited by Service Dept Vic; 07-29-2010 at 08:25 PM.
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Old 07-29-2010, 10:01 PM   #3
dusty-t
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Default Re: zd28 trans problem

I am not really familiar with the Zd28 but a lot of the zero turns have adjustments on the hydrostat for each side. Most of the zero turns that I look at either the brakes or hydro linkage is out of whack. Mind you I am usually looking at older stuff. Dusty
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Old 08-03-2010, 07:17 PM   #4
KubotaTech
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Default Re: zd28 trans problem

If the other things are ok, Drain the fluid, and check the strainer in the bottom of the transmission. If there is any metal shavings. You can also cut open the filter and see if there is excessive metal in it. If there is evidence of an HST failure, there are 2 kits available for an HST replacement. One has the 2 right and left side units, and the second has the 2 units and a charge pump assy. Hope you are mechanically inclined, there is a lot of disassembly required. Be sure to also get the add on tank to increase the fluid level so you dont have a repeat failure.
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Old 04-04-2012, 09:35 AM   #5
davemskinner
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Default Re: zd28 trans problem

A little late but it may save someone else some grief. I took apart the LH drive assembly and reground the backing plate. I also lapped the two rotors. Once back together, I used it for one season. Just before the last mowing, it really crapped out on me. It had been getting weaker but just a little.
Well, long story short, I had to replace both drive pump assemblies and purge the charge pump. All is now good. I also added the extra tank to stop the cavitation. I had planned on making my own and did not get around to it so I wish I had just bought it when I rebuilt the pump.

So my $1500 ZD turned into a $3700 ZD

Hope this helps anyone who may be doing this job!
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Old 03-26-2013, 04:59 PM   #6
leibuys
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Default Re: zd28 trans problem

Quote:
Originally Posted by davemskinner View Post
A little late but it may save someone else some grief. I took apart the LH drive assembly and reground the backing plate. I also lapped the two rotors. Once back together, I used it for one season. Just before the last mowing, it really crapped out on me. It had been getting weaker but just a little.
Well, long story short, I had to replace both drive pump assemblies and purge the charge pump. All is now good. I also added the extra tank to stop the cavitation. I had planned on making my own and did not get around to it so I wish I had just bought it when I rebuilt the pump.

So my $1500 ZD turned into a $3700 ZD

Hope this helps anyone who may be doing this job!
Hi Dave,
How did you know that both drive pumps were bad and not the charge pump. Also, i'm curious to know the cost of the parts and how you found the part numbers. What I am trying to find out is if Kubota is offering a repair kit or do you have to buy all the parts individually? I assume you also had to drop out th entire transaxle to do the job. Do you recall how long it took you? Thanks in advance? A local service department told me that the parts are $500 plus $1000 for installation but the parts pricing seems low to me.
THanks...
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Old 03-26-2013, 08:08 PM   #7
eserv
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Default Re: zd28 trans problem

Quote:
Originally Posted by leibuys View Post
Hi Dave,
How did you know that both drive pumps were bad and not the charge pump. Also, i'm curious to know the cost of the parts and how you found the part numbers. What I am trying to find out is if Kubota is offering a repair kit or do you have to buy all the parts individually? I assume you also had to drop out th entire transaxle to do the job. Do you recall how long it took you? Thanks in advance? A local service department told me that the parts are $500 plus $1000 for installation but the parts pricing seems low to me.
THanks...
if the right side works ok then the charge pump is working. Kits to repair these are $1265 per side in Canada US is usually
cheaper
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Old 03-26-2013, 08:49 PM   #8
leibuys
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Default Re: zd28 trans problem

Quote:
Originally Posted by eserv View Post
if the right side works ok then the charge pump is working. Kits to repair these are $1265 per side in Canada US is usually
cheaper
Why would the right side have relation to the charge pump and not the left. Could you clarify? Thanks for your quick answer...

Joe
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Old 03-26-2013, 09:18 PM   #9
eserv
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Default Re: zd28 trans problem

Quote:
Originally Posted by leibuys View Post
Why would the right side have relation to the charge pump and not the left. Could you clarify? Thanks for your quick answer...

Joe
Because there is one charge pump supplying charge to both drive pumps. If the charge pump fails both sides quit driving.
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Old 04-09-2013, 07:00 AM   #10
davemskinner
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Default Re: zd28 trans problem

The drive motors on each side are actually pump/motor pairs in one assembly. The charge pump feeds both drive motors. When the lefthand side of the machine is up (as on the side of a hill) the drive motor cavitates or starves for oil which causes it to rapidly degrade. Once it wears beyond a certain point, the metal circulates through the charge pump into the other side. This means you now need to replace both sides and maybe the charge pump as well. Very costly. I was able to temporarily repair the first pump/motor, but when it went the second time, it blew bad. I replaced both sides and was lucky enough to only have to disassemble and clean the charge pump.

If only one side is weak you may be able to just change the one side. However, You run the risk of destroying both the other side and the charge pump, or worse yet, if the second side fails, your new pump/motor has to be replaced again! My dealer won't replace just one.

There is lots of good info above. We have some great people here on this forum, eserv and Service Department Vic, to name a few!

Good luck and keep us posted!

Last edited by davemskinner; 04-09-2013 at 07:17 AM. Reason: spelling
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