Kubota T1600H Lawn Tractor - Custom rear end wih external hydro pump?

   / Kubota T1600H Lawn Tractor - Custom rear end wih external hydro pump? #1  

ssybert

New member
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Nov 3, 2008
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3
Hey guys,

Some of you may be familiar with the small diesel lawn tractors Kubota made in the 1990s. I think there were two versions, I have the T1600H. It features a 13.5HP 2 cyl diesel motor. There's really nothing special about it other than it's a relic and I don't want to scrap it. This particular model has a major design flaw that causes scoring on the hydraulic pump after a few hundred hours of operation. Once the pump is damaged, it fails to drive the hydrostatic motors properly. The warmer the tractor gets, the worse the problem becomes until it stops moving. The only remedy is to let it cool then go move it.

Kubota identified this problem and provided (at our cost of course) a replacement pump. The pump is internal to the rear differential. Well, Kubota has discontinued the pump and the entire rear axle assembly. other parts are available but they've clearly made an effort to kill off this machine by making the pump impossible to get.

I'd like to put another rear end on this machine and continue using the mower. I love it. It's simple, it's diesel and it's a one of a kind. It's also in great shape with only 334 hours on it.

I've never done anything like this to a mower before. I'd like to oversize the hydro pump so I can pull my aerator with ease but don't know what the factory specs are on any of these parts.

I plan to get the engine up to speed and measure the shaft rotation RPM... I assume that will get me an idea on my pump drive speed but as far as rear ends go... Any words from the wise? Recommended rear ends? Pumps? I can handle the hydraulics, fab, etc. I'm just in the dark in terms of flow rate and pressures typically used by these mowers. Do the rear ends specs the proper hydro demand?

Thanks for any input!

Scott
 
   / Kubota T1600H Lawn Tractor - Custom rear end wih external hydro pump? #2  
I don't think it would be worth the work to install an external pump. I have worked on a few JD hydro transmissions of a similar size and the pump backs to the motor with internal oil ports/passages.

I have fixed hydro pumps without any parts before, remove the pump valve plate and pistons, lap the plate and pistons heads until the scratches are gone. To prevent it from happening again, maybe look into better hydro oil cooling.

Edit: Just looked up the parts diagram for your transmission, quite interesting design. It looks like rather than a spider or planetary differential, it uses two hydraulic motors presumably plumbed in parallel with the pump. Does your tractor have a diff lock?
 
   / Kubota T1600H Lawn Tractor - Custom rear end wih external hydro pump? #3  
I was curious so did some googling. According to another TBN thread, you have an Eaton 750 or 751 transaxle. There are a few used ones on eBay for not terrible prices. They are listed as Simplicity, so possibly another way to search for replacement parts.

https://www.tractorbynet.com/forums/kubota-lawn-garden/9506-kubota-t1600-transaxle.html

It looks like you can get parts through New Holland/Messicks if it's a 751. $90 for the pump.

New Holland (989215) - LT12.5HA 12.5HP HYDROSTATIC LAWN TRACTOR W/38" MOWER (11/9-12/93) Parts Diagrams
 
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   / Kubota T1600H Lawn Tractor - Custom rear end wih external hydro pump?
  • Thread Starter
#4  
Wow. I had never considered the transaxle was manufactured by someone else. This makes all the sense in the world. I'm combing through the Massicks drawings now and comparing to the Kubota parts diagrams. Thanks Tex!
 
   / Kubota T1600H Lawn Tractor - Custom rear end wih external hydro pump? #5  
Happy to help.

In a strange coincidence, I was talking to my brother last night who was given a Woods 6180 Mow'n Machine that needs transmission work. Woods only offers the complete transaxle for over $1500 each. It turns out to have Eaton 771 transaxles, which looks a lot like a 751 but with only one final drive. According to Eaton parts drawings, 771 and 751 share many part numbers including pumps. So I'll be curious to see what you find out on yours as far as parts availability, he may be looking for the same or similar ones.

Add Ferris to the mix using Eaton transaxles, although they re-number Eaton's parts on their drawings so it's harder to match them up, and they're twice the price of Messick's New Holland prices.
 

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