Steering adjustment - how to loose the slop
I recently bought a YM1110d. Great little tractor. One of my initial complaints was that when the tractor was driven through rough terrain (say a recently tilled field) that there was quite a bit of steering feed back. What I mean is that when the front tire would hit a clod of dirt the tire would try to turn which would then cause the steering wheel to rotate. This a great way to get a broken thumb. The tractor would also trac poorly when transporting down the road. It felt as if the steering wheel was connected with some bugie cords. You could turn the wheel slightly in either direction with the tractor not changing it's course. Here's how I eliminated the problem:
The first thing that I noticed was that the axle was leaking from the wheel hubs. A check of the dipstick showed the axle to be very low. I added 80w-90 oil to the full mark. The axle now leaked worse, proably due to the higher oil level. I drained the axle and found it to be full of water. The axle was torn down for a complete reseal (thankyou Gbirky) which was suprisingly easy to do. Absolutly no special tools were required for my axle. Just take your time as some parts will fall out uppon dissambly, and you won't know exactly where they came from. I'd recommend disassembling one side at a time so you can refer to the other side for reassembly. Upon the examination of the wheel bearings, I notice the roll pin which retained the castle nut had disappeared thus allowing the castle nut to loosen. The incorrect bearing preload allowed the axle to wander thus detroying the seal. This is definetly something to check into if your axle is leaking. On my axle design, there is a bearing supporting the vertical shaft at the very top of the axle, directly under the steering arm. It was obvious upon dissassembly, that this bearing was being starved for lubrication. It's for this reason that I overfilled the axle with gear lube upon reassembly. It's my hope that the higher oil level will allow some oil to splash up and catch this bearing. Other than the loose castle nut, it was very obvious that this was going to be the first bearing to fail due to poor lubrication.
The next area of attention was the axle pivot point. Over the years, my axle pivot had worn into the shaft and the bushings had worn out. A new shaft was installed and new oil bearing bushings were installed. There was quite a bit of slop in the axle pivot and I would recommend everybody keep an eye on this point. It's easy to ignore it because it's out of sight. Unfortinatly, the pivot point on my tractor is not greasable, which was a error on Yanmar's part.
At this point, there was no more feed back comming from the wheels. However, the vauge center to the steering wheel still remained. I checked all the ball joints for slop and binding and they all checked out OK. If there is any sign of movement to the ball joint, then the joint is bad. These are super easy to replace so just order the part and do it! And be sure to grease them! These tractors need grease to live!
The next point of attention was the steering gear box. This box turns the rotational movement of the steering wheel into a linear movement. It's located at the bottom end of the steering shaft. Mine is painted black. When you turn the wheel look at the output side of the box. Does it seem as if there is a little play in the box? If so, then adjust the sector shaft. On the side of the box, there will be a screw with a jamb nut. Mine takes a flat screw driver. Hold the screw in place and loosen the jamb nut a couple of turns. Now start turning the screw in by 1/2 turns. Keep checking the wheel. I found that after 2-1/2 turns, I could no longer turn the screw in by hand. At that point there was a slight amount of resistantance in the steering box. Not enough to make it hard to steer. I also noticed that there was absolutly no play in the box any more. I retightened the jamb nut, making sure the adjustment screw didn't move and then road tested the tractor. The steering is now tight with absolutly no vauge center. At top speed, you can take your hands off the wheel and the tractor will track straight with no desire to wander to either direction. Driving off road, the feedback from the tires is gone. The cost for repairing the steering was minimal ($150 for all the axle seals and a few bearings) and the rewards were well worth the effort. Most of this can be called preventative maintenance and I'd recommend every tractor owner to look into these items on their tractor.