Kubota L2550 Steering Slop / Play

[emkothe]

Working on an L2550 with about 1/3 turn slop in the steering. It is all in the steering box on the front of the tractor. As you turn it back and forth the 1/3 turn the input shaft "walks" in and out of the steering box about 1/8" to 3/16" without moving the output shaft. I do not think there is any power steering either, but not sure if it is a result of no hydraulic pressure, or the above mentioned "slop".

I presume this "walking" of the input shaft is not normal? I only have a parts list to look at. Thinking the little thrust bearing inside are gone? Maybe the hydraulics failed first and using the tractor without killed the little bearings?

This is not my tractor and there is no history available, so I am guessing before I take it apart.

Anybody have a manual that they could "share" the power steering section of?

Any thoughts appreciated.

Mark

 

[brady-yzf]

I've got an L35 manual I could share, I bet they're similar, let me know if you want it.

 

[emkothe]

I have attached a page from the parts manual to show you what it looks like (exploded view though) The part number of the assembly is 30400-66100.

If yours is the same I would love to see the part of the steering section that discusses reassembly.

I can usually get things apart on the first try, but not necessarily back together in 1 try.

Mark

 

[brady-yzf]

Mark,

Sorry about the delay, I forgot to bring my manual to work so that I could reply. It turns out that the steering on my L35 is nothing at all like yours, mine is part of the main hydraulic system

 

[emkothe]

Thanks for checking.

While this "looks" like it uses the main hydraulics the gear box shown is on the front of the tractor with a long input shaft on the right side of the tractor. This connects to another steering box that goes to the steering wheel.
Mark

 

[emkothe]

I have it apart now.
There is a spool valve in the gearbox. WITHOUT any hydraulic pressure to the box the input shaft can turn about 1/3 rotation without moving the reciprocating ball nut (it is the piston too) that is connected to the output shaft. The walking in and out of the input shaft is what actuates the spool valve to provide the power assist. If there WAS hydraulic pressure the free play would not be recognized because power assist would be moving the output shaft.

Again, if there WAS hydraulic pressure at the box. I presumed that because it had oil that had leaked out of the output shaft, and that the lift worked on the back of the tractor there was pressure at the steering box. My bad, I now know that the pump is actually 2 separate pumps. Due to a poor design the power steering pump bushing (fig 1) (the rear 1/2 of the pump) do not get sufficient oil and become hard to turn. This breaks a small bronze coupler (fig 2) between the 2 pumps. When that breaks it is caught inside a hole in the pump. It acts just like an expanding brake shoe and drum. When the primary pump shaft cannot turn the coupler any longer it finally breaks the end of the shaft(fig 4) off and runs freely. The primary pump still runs, but then the steering goes sloppy. Since this is a 2nd owner they never knew the difference.

I have learned. I am still glad I took the steering box apart though. There was plenty of black oil to clean out, and I can fix the seals that leak. As for the pump, the bushings are fine once cleaned up and resized a little larger. I opened the oil grooves to the same size as the grooves in the primary pump. Kubota does not service the coupling or primary pump shaft that has the drive end broken off, except by complete pump replacement ($500). I am going to weld the end of the shaft and machine the "key" back on the end and either weld the split in the coupling, or more likely just make a new one. The coupler is really only a piece of 5/8 rod about 1/2 inch long with a plus sign cut in the end.
Fig 3 is the primary pump bushing, fig 5 is the power steering pump driven gear.

Glad I have all Winter to fix it.

 

[emkothe]

Final saga.
I MIG welded the end of the broken shaft and machined it back to size. Made a new coupling. Opened up the ID of the bushings and enlarged the oil groove in the bushings of the power steering pump. When I originally disassembled the power steering half of the pump the shafts were mildly seized in the bushings. Hopefully increasing the clearance and oil groove will prevent future seizing.

Hooray, power steering is back, and all the slop is gone too.
Mark

 

[dshadley]

Final saga.
I MIG welded the end of the broken shaft and machined it back to size. Made a new coupling. Opened up the ID of the bushings and enlarged the oil groove in the bushings of the power steering pump. When I originally disassembled the power steering half of the pump the shafts were mildly seized in the bushings. Hopefully increasing the clearance and oil groove will prevent future seizing.

Hooray, power steering is back, and all the slop is gone too.
Mark

wait a go mark! i think i've got the same problem on my l-2850-gst,half a turn on the wheel before shaft on box moves. yeah in & out too, power steering works but not good. thanks to you i feel more confident about ripping into it, dave

 

[boone]

Brilliant!

I just did that exact repair on an L-2650 and replaced those same parts. Kubota has a very detailed TSB (Technical Service Bulletin) that details exactly your findings and an interchange part that is substantially upgraded that connects the two pumps that are piggy-backed on these L-1 Series Kubotas.

Didn't think of the Mig repair route, fantastic!

I know this is an old thread, but sounds very much like a problem I'm having on my L2550-DT. The power steering appears to work, but it has lot of play. I can turn the wheel 1/3 of a turn before the wheel actually begins to move. The steering gear case located under the pump seems fine. The joint shaft coming out of the gear case leading to the manual steering gear box turns instantaneous with the wheel - no play there. After reading this thread it appears as though emkothe found the problem to be with the power steering pump and not the steering gear box under the battery.

Is it still true in 2017 that you can't get parts for the coupling between the pumps? Service Dept Vic, if I were to crack open the dual pump and find the coupler broken between the PS and 3 point pump, what parts would I need to ask for from the dealer? You mention a TSB and updated interchange part.

 

[North Idaho Wolfman]

boone,
The coupling is P/N 37410-76470
http://www.colemanequip.com/parts/KubotaParts/37410-76470/

 

[boone]

boone,
The coupling is P/N 37410-76470
http://www.colemanequip.com/parts/KubotaParts/37410-76470/

Thank you Wolfman! I found an online parts breakdown. Looks like the coupler is sold separate from the gear and bushing set. However, if one of the primary shaft is broken I'll be looking at buying P/N 31351-76402 at $273

I guess that's still cheaper than buying the whole pump. I don't trust my welding skills to weld the gear shaft. Maybe I could take it somewhere to have the shaft welded.

Do you know if there is a quick way to determine if the PS pump is failing? I thought I had read somewhere, one could could remove the banjo fitting at the pipe on top of the PS pump? I would assume after starting the tractor and turning the wheel none/some/a lot of fluid would come out if it's broke?

 

[North Idaho Wolfman]

Loosen a fitting off the pump and with a bucket under it start it up, if you get a lot of flow pump is being driven.

 

[boone]

Makes sense - that's what I'll do. Thanks for the quick reply.