Toe-In Setting

[bill18163]

I have a L3940 four wheel drive Kubota. I checked the toe-in of the front wheels yesterday and found that they needed adjusting. Toe was "0" to just a little bit "out". Operators manual calls for 1/16" to 5/16" toe-in and the Work Shop Manual calls for .08" to .300" which is approx. the same. The L3940 is adjusted by turning the tie rods on each side. I noticed that there was more thread showing on one side than the other but I accepted that the factory had the original setting correct and went ahead and adjusted both sides equally for a toe-in of 5/32". A question entered my mind later on. Since each wheel is adjusted by its own tie rod, how do you know that each wheel by itself was pointed straight forward with no toe when I first started? I know I got "0" toe-in on my gage when I started but how do you know the two tires were pointing straight forward? Is there a way you could tell if a tire and wheel is pointing straight forward with no toe in relation to the tractor? That way you could set both tires each by itself with "0" toe for a starting position and then adjust each equally to get the necessary toe-in. I know there is a possibility that I am not understanding this whole procedure in regards to the geomertry involved so if there is anybody that has some experience with it please set me straight.

[K7LN]

Normally, it takes a fair amount of good instrumentation to do what you're asking. There's nothing to say that you can't set up a rough check on your own, depending on what tools and gadgets you have on hand. The first thing that is done is to set the steering wheel to it's exact center position. Often times, the steering shaft will have a mark on it that will indicate exact center. If not, you have to set your center position so that you have an equal number of turns to reach both left and right end of steering travel.

From that point, you have to set up some type of measuring system to see if the wheels are parallel to the frame. This will depend on what you can work out with what you have on hand. The processes are too lengthy to describe here, but if you can devise something with cheap laser pointers, that works out well.

Lacking any measuring system and you have one side with many threads exposed and the other with few threads exposed, just turn each side the same number of turns in opposite directions until you're comfy with what you see. Then do a normal toe-in adjustment. If you end up driving straight with the steering wheel pointing in some direction either right or left, readjust the toe in a manor to favor a straightening of the steering wheel. For those that have hydrostatic steering systems that have the orbital valve, forget about trying to get a straight steering wheel since these systems work differently.

[slowzuki]

It has an orbital valve, the steering wheel never centers to the same place. Don't worry too much about the threads, if they are at all close, the tire hits the steering stop long before the ram runs out of travel.

[zzvyb6]

If the front axle is symmetric and the tierods are the same length, you should expect to have the same number of threads showing on both. Otherwise, the steering gear is not centered and you will have a different turn circle left to right, even thoough the toe is correct. You can also check this with the number of turns of the steering wheel in both directions. Try to do this with the wheels off the ground because the loading on the gear can affect the position control in a power steering valve. To check absolute toe, just measure the forward and rearward lateral locations of the rims. Try to get them at the spindle height if possible.