Oil & Fuel Hydro transmission stil jerky after oil change :-(

[easygo]

The tractor is a B7510 HST. I posted a question about this a while ago. Several of you guys suggested I should change the hydro fluid. I changed the fluid and filters and cleaned the strainer. Refilled with SUDT. Unfortunately the problem remains about the same. When I operate the tractor at less than 2000rpm there is a noticeable jerk when I step on the pedal, regardless of loader on or off the machine and load or no load. It is not so obvous, but sometimes does it even if it sits on level gound and I press the pedal down very slowly. It seems to happen less when the RPM is about 1800 or above and when the engine reached operating temperature. Would you give me some more pointers on where to continue with my problem solving? Is this normal on HST units?
easygo

 

[Taiser]

Does it jerk only when you depress the pedal the first time, or all the time? For instance when you're travelling at a constant speed does it jerk? The tranny should be smooth all the time, no jerks. If it's only jerking when you first hit the pedal then I'm guessing it's a linkage problem with one of the pedals. I doubt it would be the tranny unless it's happening while in motion. Wrong tranny fluid might have caused the problem too, but you just changed that.

 

[easygo]

Thank you for the reply. It does jerk when i first press the pedal and if I'm moving it is smooth. Sometimes it gives another jerk when I'm moving up a small not too steep, short hill. What can cause this and more importantly what could get broken if this is not fixed? How do I check the above mentioned linkage? Please give me some pointers. The tractor is still under waranty, so would this problem be covered?
thanks
easygo

 

[pemad]

Just a suggestion.
Did you change the fuel filter?
If not, you may want to try this as you may have water in the fuel.

Enjoy!

 

[art]

Get it to a dealer, drive another one to see if it is the same or different. You sholud be covered.

 

[easygo]

I guess I will have to get it to the shop. I just don't like to deal with the dealer. Thanks for the replies. Sigh....

 

[CampMan]

FYI:
I have a B7510, new last year. I had the exact same problem. The tractor would jump ahead as u tried to take off slowly. And during mowing on a slight upward grade it would feel like it went into another gear.

I had a service man come to my yard and adjust the linkage and things are OK now.