F687 z-trak steering problem

My z-trak wanders, it will not stay straight even on level ground. It does not track to just one side, it wanders from left to right. I have adjusted the levers as directed in the manual and it still wanders. The freewheel valves are closed tight. What do I look for now?

How old is it?

Make sure rear wheels are attached correctly and the pumps are not loose from the frame. Make sure frame has no cracks.

Has the hydraulic fluid ever been changed with a new filter?

0 turns are sensitive. Took me a while to adjust to using one. If older, there is a shock absorber on the linkage somewhere that helps stabilize movement. Make sure that isn't worn out.

Make sure the linkages do not have any slack. A 1/8" slack will let the handle move 2".

If the fluid hasn't been changed, there may be water in it and the wandering could be when water hits the pump. (Wild guess) I am not sure what else would cause the controls to act like that.

When you say 'level ground' are you on pavement or are you in a yard?

The reason I ask is that in a yard there is always small undulations in its texture and there is no way the machine can compensate for them. You, the operator happen to be the compensation mechamism, you constantly adjust the handles to travel a straight line.

As they have said none of them run straight on side hills nor rough ground, that is if you define straight as compared to a 4 wheeled lawn tractor. That being said after a few hours several issues make them progressively harder to keep going straight. Wear in the linkages, as somebody said you dont need a 1/2 of slop somewhere to have a problem. 1/8" in the joint under the levers translates into a lot at the handles. Having the correct amount and same pressure in the tires helps too. How many hours is on it? The big money deal is the hydros themselves. Unless the fluid looks bad, or is the wrong type or has never been changed in 1000 hours dont expect miracles from changing it and the filter, nice in theory but seldom see fixes in my world. Real problem is as the hydro motors and pump wear and progressively by-pass more oil the machine becomes more susceptible to being steered by bumps, holes and side hills. My experiance with them in general is that prior to the point that leakage causes issues with travelling speed or torque it will impair steering to the point that something must be done. Depends on the operator(s), some dont care how much they zigzag when cutting. Also depends on how steep the terrain is. Some will repair and replace pumps and motors when the machine gets hard to steer. Biggest problem is unless there is an early life failure seldom does it make financial sense to install new pumps and wheel motors in a high houred unit. Oh you can chase your tail around replacing one, then the other but seldom does the fix for high houred machine occur until both pumps, and both motors have been replaced, just my experience.

Thanks for the replies. This machine has about 1200 hrs showing on the hour meter. I guess I can live with the wandering steering after looking at the pump replacement cost. All steering joints are tight. The shock absorbers are new and I can not find any cracks or anything that may cause the level linkage to move the pump levers without the steering levers being moved. Again, thanks to everyone that responded.