2006 Kubota rtv 900 won't move in any gear

Tbuck1990

New member
I purchased a used rear differential off of ebay. It was cheaper to buy this since original housing got a hole and mangled the gears inside old one. I got it bolted up put All linkages back together and put back in machine. All the linkages seem to go into gear fine and I am 100% positive brake is off because when it is on I can't move half shafts. I have the rear axle off and just half u-joint shaft in tranny. What am I missing? I'm running out of ideas here. I don't remember if machine was in neutral when installed. We have 8 Kubota here and I looked at our old ones when putting everything back together any advice would be great I really don't want to drop motor and tranny cradle again but maybe will have to?
 

Doc

Admin
Staff member
Gold Site Supporter
Hey Tbuck, welcome to our forums. :tiphat: Glad to have you.
I do not have any suggestions for you at this point, but I'm sure some of our wiser members will be along with ideas soon.
 

aurthuritis

Well-known member
Site Supporter
have you checked to see if the shifting forks are actually putting the gears together? could be that the selector is moving but nothing is shifted in the tranny?
 

ovrszd

Well-known member
If you put the shifter into any gear, then try to turn the axle shafts do they turn freely? This would indicate that the gear selector isn't putting the HVT into any gear.
 

aurthuritis

Well-known member
Site Supporter
If you put the shifter into any gear, then try to turn the axle shafts do they turn freely? This would indicate that the gear selector isn't putting the HVT into any gear.

i am probably just being picky so please excuse me. the HVT doesn't really have any gears that can be selected. think about it like this. there is a hydraulic variable displacement drive that drives a conventional two or three speed constant gear drive transmission. it is possible to have a broken shaft or connector between the hydro and the gear tranny. so it is possible to have a hydro problem or a gear problem, should check the hydro filters for debris, because i don't think a stalled hydro will kill the engine but a locked up hydro would. follow the flow of power from the engine into the hydro and then into the tranny and finally through the diff to the wheels. in a normal functioning machine it is possible to stall the hydro in any gear without killing the engine. the fact that the engine keeps being killed leads me to believe the problem is in the hydro and not the tranny just my two pennies:bonk: like i said, check the filters. i would bet they are full of yellow metal.:wave: something else that could be remotely a problem is a hung starter.
 

Tbuck1990

New member
Thanks for the info guys. When I put gear selector in any gear it feels like selector is going into gear. In neutral I can turn shafts with little effort. In a gear I can turn shafts but is harder to turn. I read that fork can pop out of the selector stud. Is the shaft inside the fork supposed to sit in the 2 square groove halfs? Tommorow I will look into this more. Is it possible something else isn't lined up right? I would think that rear diff housing wouldn't bolt up to tranny right in that case? Maybe I will unbolt gear selector on top of another machine tommorow and see what that looks like for lining up fork and stud.
 

ovrszd

Well-known member
i am probably just being picky so please excuse me. the HVT doesn't really have any gears that can be selected. think about it like this. there is a hydraulic variable displacement drive that drives a conventional two or three speed constant gear drive transmission. it is possible to have a broken shaft or connector between the hydro and the gear tranny. so it is possible to have a hydro problem or a gear problem, should check the hydro filters for debris, because i don't think a stalled hydro will kill the engine but a locked up hydro would. follow the flow of power from the engine into the hydro and then into the tranny and finally through the diff to the wheels. in a normal functioning machine it is possible to stall the hydro in any gear without killing the engine. the fact that the engine keeps being killed leads me to believe the problem is in the hydro and not the tranny just my two pennies:bonk: like i said, check the filters. i would bet they are full of yellow metal.:wave: something else that could be remotely a problem is a hung starter.

Oooppss, I think you put this post in the wrong thread?
 

ovrszd

Well-known member
Thanks for the info guys. When I put gear selector in any gear it feels like selector is going into gear. In neutral I can turn shafts with little effort. In a gear I can turn shafts but is harder to turn. I read that fork can pop out of the selector stud. Is the shaft inside the fork supposed to sit in the 2 square groove halfs? Tommorow I will look into this more. Is it possible something else isn't lined up right? I would think that rear diff housing wouldn't bolt up to tranny right in that case? Maybe I will unbolt gear selector on top of another machine tommorow and see what that looks like for lining up fork and stud.

Sounds like your forks are fine. The difference you felt is normal. If the selectors wasn't working there would be no difference.

I'm not familiar with the exchange you did, so will ask dumb questions.... You didn't exchange the complete system from the engine back, just the differential section?
 

Tbuck1990

New member
Yes I call it 3 different sections the motor then tranny then rear differential. My rear differential blew a hole in housing. Also broke some internal gears. That's why I found a used one on eBay that was cheaper and eaysier to install rather than getting a housing and labor tearing all the way down to swap parts over.
 

aurthuritis

Well-known member
Site Supporter
might try with the diff lock engaged to see if that makes a difference? also i think there is a spline shaft with a coupler that connects to the hydro to the transmission. could that be stripped? but in afterthought you say that when you put it in gear you can feel the resistance of the hvt? correct? could it be that your hydro isn't turning? have you put any pressure gauges on it when running?
 

ovrszd

Well-known member
This is totally an assumption on my part. HVT was working fine. Rear differential failure which resulted in a destroyed diff case. Rear differential was replaced, retaining the original trans and HVT.

The KISS principle would suggest that the drive mechanism between the trans and the rear diff is somehow not connected??
 

aurthuritis

Well-known member
Site Supporter
before you take anything apart make sure the servo valve on the top rear drivers side of the tranny is adjusted correctly. also and probably before you adjust the servo valve you should check the other servo on the top of the hst that controls forward and reverse direction. most people will find this in "how to adjust creep adjustment on KUBOTA rtv" google
 

Tbuck1990

New member
Update

I changed hydro filter nothing changed I still have no movement in any gear. How do you adjust the hvt? With diff lock on that engages properly but still no movement to drive shafts. Also in 4wd I have no movement as well. I took linkage control cover off and manually start machine. And manually switch gears but have no movement in any gear. Only shaft moving is the constant one from the flywheel. What's best way to hook a pressure test up for hydro?
 

aurthuritis

Well-known member
Site Supporter
OK just found some more info that might be helpful. it could be that the hydro charge pump is dry and won't pick up prime and charge the hydro. you can try to add clean oil to the filters before you put them on and also can cycle the pressure relief valve that is attached to the brake cable on the rear of the transmission or if your lucky also a knob on the dash. while the engine is running with rear wheels off of the ground and the peddle inabout half cycle the valve and see if it picks up oil...might have to disconnect the hydro lever from the linkage and let the engine idle while moving the lever from forward to reverse slowly.
 

ovrszd

Well-known member
In regards to the filters. If you put on new filters empty, and you remove them now after running the engine and they are still empty, it's almost certainly a prime problem. If you remove one and it's full of oil now the pump has primed itself.
 
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