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1641 cub hydro jerks,aggressive, wheelie,

3467 Views 10 Replies 5 Participants Last post by  MikeXcr600
Hello everyone, this is my first time posting over on the cub side, and also the first cub I've ever owned. I have a issue with the hydro unit, I will first start by saying i have owned a john Deere 316 and 317 and i'm comparing the cub 1641 to them as far as the hydro control lever goes. The john Deere had a smooth motion from forward to reverse, The cub when going from forward to neutral or reverse to neutral comes to a very dead stop when it hits neutral, then slowly engaging in either direction is very aggressive, for example if in reverse and you move the lever to neutral, it comes to a dead stop flinging your body over the steering wheel, then you slide forward and it practically throws you over the back of the seat, and pops a small wheelie. Does anyone have any suggestions. Ps the hydro doesn't make any whine noises, or grinding, and does not creep while in neutral
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The linkages are worn and sloppy or out of adjustment.
Somewhere between the control handle and the swash plate there is wear/slop.

Exterior linkages are the first thought, but there is also a wear point on the interior.

Variable displacement piston pumps are inherently balanced. They want to stay in a neutral (no pumping) attitude, or something very close to neutral that doesn't generate much by way of pressure. Any slop will first have to be taken up before the swash plate begins to move, If there is no slop after that point, the swash plate jumps to the correct position, and the tractor accelerates rapidly to the speed that the flow dictates.

Picture a round shaft with wear from a rocking motion. The wear is only on a portion of the circumference. Once past that wear area, the action tightens up.

Check for wear at the neutral position. Any motion of the drive control from neutral should also result in a corresponding motion of the swash plate trunnion shaft where it enters the hydro case.

A hydro swash plate only has 15 -20° of deflection available in either direction. A small amount of wear in the wrong place can cause your problem.

It is a mechanical, as opposed to a fluid, problem.
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