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So, here it is December in Wisconsin and one of the snowiest winters in years. I think it is appropriate to say a few words on checking front axle (steering), u-joints in a vehicle that has u-joints rather that CV joints. Since I am still new at web posting I don’t have pictures yet, but will add something soon. First of all, the u-joints in the front of a truck or SUV get more abuse that any others. This is because they are forced to turn shafts at tighter angles than anywhere else on a vehicle, and because they go for long periods without turning at all. Not turning allows the ever-present moisture to build up some serious rust, and then when these joints are used, the rust can prevent the needles from rolling freely. Needles that don’t roll end up sliding on the shaft and cup and get flat spots while gouging the surfaces they contact.Here is how to check for these problems: raise both wheels off the ground, or one at a time, and steer the wheels all or nearly all the way either right or left. With the axle shaft engaged to the hub, spin the wheel by hand.  If the u-joint is in good shape, the wheel will turn freely and with even effort throughout each revolution. A binding u-joint will cause the wheel to be alternately hard to turn then easier through each revolution. Now steer the wheel straight ahead and turn the wheel again. If it turns more freely now, you have identified the u-joint as the problem. Repeat the test to verify your conclusions. Keep in mind that other things can cause hard and uneven turning. A warped and especially a cracked rotor, can cause uneven turning effort, but steering the wheels should not change this. Next, get a look at the joints. Is there obvious looseness? Rust staining that is lighter red that the rest of the rust in the area indicates rust that is getting scoured by movement, like those bearings inside the u-joint.

Why should you care about fixing a tight u-joint in this axle assembly? Eventually the tightness caused by rust will give way to excessive clearance and, over time, damaged shaft parts. Also, a tight u-joint can damage the bearing inside the spindle and the hub innards with excessive side loads. It all adds up to more expense and the possibility of failure when you most need four wheel drive-when you’re stuck!

How to replace these bad parts will be a future topic.

This discussion leads to other related issues, like what are CV joints and why are they becoming more popular than U-joints in some applications? I will post those answers soon.