I have a Kubota RTV 900 with a variable hydro transmission. It has about 300 hrs on it and all the fluids and filters have been changed regularly. I notice that when the RTV is run for a while and the RTV is in high it seems to be slipping a lot. When I first start it (cold)and take off the transmission seems to be working fine but as it heats up the transmission seems to slip a lot. By slip I mean when I am at a dead stop and then hit the go pedal it revs up but doesn't seem to want to go. It takes forever to get up to speed. Does any one else have this problem? Is this normal for this Kubota? Thanks...
VHT Slipping?
- Thread starter Smith14
- Start date
I know nothing of your particular machine......but........
Some have a bypass valve, a relief valve, when the pump or trans get hot the fluid passed through the valve and power is lost.
Sounds like your pump is on it's way out......just a guess.
Some have a bypass valve, a relief valve, when the pump or trans get hot the fluid passed through the valve and power is lost.
Sounds like your pump is on it's way out......just a guess.
I hope it doesn't have a bad pump. It only has 300 hrs on it. I change the fluid an filters regularly.
It came with SUDT or SUDT2 fluid which performs better in hot and cold.
I can't say for sure it's the oil but it seems funny that it was fine before the oil was changed and it does fine until the oil gets hot right now. I know the book says UDT is fine and the dealers say UDT is the same and tons of people will say they use UDT and never have problems.
I say yes, UDT is a quality fluid but;
Kubota factory fills all it's equipment with SUDT/SUDT2 so it will perform at the highest possible level.
At service time we then have the choice to either keep the same grade fluid and performance or go with a lower grade fluid and loose performance.
Good point. It has only begun to act like this after the oil has been changed. I'll have to try the SUDT and see if that makes a difference. What is the difference between the SUDT and the SUDT2? which is better?
Old thread I know, but I am having the same problem. When cold, transmission works fine... but as it warms up, it gets progressively worse... and it hot weather it gets worse quicker.
I had a similar issue with my JD mower, and it turned out the hydrostat transmission was underspec'd from the factory, and found a fellow that sells a kit to upgrade it from the K46 to the K66. I certainly hope the same issue isn't happening with this RTV.
We got this used (and it was pretty neglected, but not many hours). We've changed the fluid, filters, etc. with all new Kubota stuff from the dealer, no difference. Engine starts and runs fine.
I had a similar issue with my JD mower, and it turned out the hydrostat transmission was underspec'd from the factory, and found a fellow that sells a kit to upgrade it from the K46 to the K66. I certainly hope the same issue isn't happening with this RTV.
We got this used (and it was pretty neglected, but not many hours). We've changed the fluid, filters, etc. with all new Kubota stuff from the dealer, no difference. Engine starts and runs fine.
the engine rarely fails, probably the toughest part of the whole unit
the transmission is the most piss poor excuse for a UTV transmission. It is not a CVT, and a lot of people are scared of CVT's for a lot of reasons (Usually people posting garbage on the net about how bad theirs was). Then we talk about the RTV's and how great they are. They're ok, but they real sensitive to fluid, filters, temperatures, and finally wear. It takes very little wear on the wear plates inside the hst to cause problems. The fluid MUST be super udt 2, everything else is susceptible to "slipping" as temperatures change. The temp has everything to do with viscosity of the fluid and the viscosity has everything to do with how well the hst works. Lower viscosity=more "slippage" and it gets worse with temperature as the transmission cases and parts warm up which makes viscosity even lower with temp which causes more slippage--it snowballs. Super UDT is not quite as sensitive to fluid temps, and kubota OEM filters flow better than aftermarket (regardless of what they say); both of which help the VHT trans work betterr. They are still somewhat sensitive to heat and by design there is no getting away from it but using the correct fluid does help.
This assumes that there is nothing wrong internally. I didn't see a lot of issues out of transmissions on the RTV's but when I did it was almost always fluid related. Cheap fluid cheap filters, hurts the wear plates and cylinders/rotating groups, etc.
Yes, it was UDT2 fluid, and all OEM Kub filters.... I feel like something is just plain worn out. Because when it gets hot, it'll barely move. The hydrostat part inside the back, from the picturtes/videos I've seen, looks just like the guts of the Tuff Torq units that fail on the JD riders (and I'm sure others). But it looks like the RTV also uses a "charge pump" ahead of that, that is only accessible once the right axle and brake assembly are removed.
It's been like this since we got it used, with the property. And it's getting worse to the point that we can barely use it anymore.
It's been like this since we got it used, with the property. And it's getting worse to the point that we can barely use it anymore.