Thanks. i can't tell from photo all i can do is try to interpret from what you say. that photo doesn't look all that bad. definitely get new orings though. what i meant from corrosive or abrasive environment was "the environment inside the transmission" based on the condition of the wear surfaces,your description and the oil when you first changed it.
Kubota RTV 900 transmission problem - hardley moves in gear!
- Thread starter PACKASAURAS
- Start date
cheapest price i can find online for the kit is 2400 dollars
can you remove the pumps from the barrels one at a time? don't mix and match as they are matched to their location. yes tose liners should be replaced. every thousands of an inch lost in fitting in every part all adds up to lost performance
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sent you a PM.
look at the pumps pictured in the PM. compared to yours they don't look real different so i may be wrong about the dis colorized parts. the only true way to test the pumps is to see how much pressure they will carry. sadly you need to reassemble to do that
look at the pumps pictured in the PM. compared to yours they don't look real different so i may be wrong about the dis colorized parts. the only true way to test the pumps is to see how much pressure they will carry. sadly you need to reassemble to do that
Thanks, I have had each pump out individually and cleaned cylinders, block and springs and put all back in original places - no significant wear or damage was noted. The liners don't appear damaged but it looks as though the swash plate has damaged the casing, compressing it over the liners in one part. Just shows what kind of pressure runs through these things?
if it had plenty of torque to the wheels just not speed. it might just hopefully be the swash plate wasn't getting full travel. how much trouble would it be to lube and reassemble with new orings in the servo piston bores. readjust everything to center and try it out? and before any more disassembly check the pressures on the high side? now that you have been so deep into it you could probably make some pretty educated judgement from what you have seen and how it performs.
before you reassemble you need to at least get that extra metal out from under that liner.
before you reassemble you need to at least get that extra metal out from under that liner.
It would manage hill climbs ok,and with a full load, just very slow - i trust this show decent torque at wheels? There was very little oil in piston bore and lever assy, however i guess this should be expected when engine is not running. There were traces of oil on surfaces when opened/piston withdrawn. Do we think piston was simply binding on O rings and not moving rather than the piston being faulty? Is there a way to test the piston? How does oil get lifted into this area? A friend has advised this suggests over heating of oil? In order to get tranny casing off do i need to drop axle? How does oil get lifted to this area? I suspect the elongated hole on the swash plate and pivoting point for guide is responsible for restricted speed? So frustrating having to open up to get swash plate out...!! Thanks again.
i think the servo piston was not moving a full stroke. why i am not sure. could be leakage around the piston seals or it could be that spring and stem in the center of the piston. could be the spool valve was out of adjustment. remember that the swash plate controls the speed and the swash plate is moved hydraulically by the servo piston and the servo piston is controlled by the spool. when the engine isn't running and the charge pump stops all oil returns to the case.
Remember I did screw the servo screw in four complete rotations and it did move inwards....this suggests there was movement in the piston. If it was seized this wouldn't have happened? If i am happy with the condition of casings, perhaps the best way forward is the refurb kit?
Question>>> what if the piston is seized internally on the stem??? or the stem is limiting the travel?
the stem and spring are a way of keeping the servo piston centered and the hydraulic pressure on either end is controlled by the spool sending pressurized oil to either end of the servo piston. the piston reacts by moving against the internal spring pressure and moves a little bit until the feedback lever moves the spool canceling the command and holding the servo against the internal spring. if the seals were leaking the servo would be limited. if the internal spring and stem are in a bind or corroded then the servo can only move a little bit or none at all. the external stem is a means of centering the servo so the swash plate command is neutral. make sense???
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True....so many variants....I am very tempted to throw back together and re-test!! But it is quite time consuming and will likely need opened up again!! That elongated hole on the swash pivot will not do performance any good, the time taken to travel, displacement of swash angle etc will all have an influence on power out? Still very tempting though!! I guess i should put back together in order to powerwash prior to removal of the rear hst as a unit.
the elongated hole in the center of the swash plate is by design. although all wear in the control surfaces all add up to reduced travel. while you have it down and servo piston in hand i would examine how easy it will travel back and forth on the stem. maybe get some oil in there and work it and flush with fresh oil to see what comes out. and pay attention to see if working it increases the travel distance hack and forth.
i went back in the photos and now i think i understand what " elongated hole" you were referring to. to make it clear the hole is in the paddle of the swash plate??? definitely needs to be compared to a new one as this could be the loss of travel on the swash plate.
sent you a PM. let me know what you find out please?
The hole I am referring to is the one on the top surface of the main pump swash plate. It has a block with a hole drilled in it to accept the metal "dowel" which accepts the guide, which runs in the piston channel. I have tried to simulate swash plate left and right and at max positions it does not get anywhere near the casing (i thought it must have been striking this to cause damage). The damaged area also lies directly below the guide block which sits on the "dowel" so the only thing that could have caused the damage is the guide block which sits on the swash plate. This leads me to think the piston must have been seized/sticky, putting pressure on one side and the constant rocking motion resulting in the hole (accommodating dowel) enlarging and causing damage to the guide. The swash plate must be a softer metal than the guide as it has suffered more. The dowel rocks round all over the place in the hole in the swash plate and will not be transferring motion from the level assembly. Unless when i have been opening i have disturbed guide and it hasnt fully engaged? Although i suspect this amount of damage has occurred over a long period of time? At the very least i need to change that swash plate and piston (I think!). Do i need to drop axle to get tranny opened up and out? Does anyone else's piston housing have this rough casting appearance inside? Thanks
