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Taking care of tapered bearings

This precision part often gets less attention than it deserves.
Monday, August 27, 2012 - 07:52
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I first picked up a wrench “professionally” at age 15 and that was a long time ago. Many of the cars I worked on early in my career still had drum brakes at all four corners, so servicing tapered roller bearings was something I learned early and practiced often. It’s one of those basic tasks we perform without really thinking about it. So you’re probably asking yourself the same thing I did when I first took on this topic. What on earth can I learn about the proper service and care of this very basic component? I think you’ll be surprised.

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It’s especially easy to take those little routine tasks for granted after a while, isn’t it? How much thought, really, do you apply to the task at hand when performing a job that you’ve done a hundred times over? It is that exact same repetition that leads to taking shortcuts that, in turn, impacts the quality of the repairs we make. Shortcuts that are unintentional for the most part, but shortcuts nonetheless. And when it does finally come back to bite us on the backside, its human nature to blame the part for the early failure.

While on occasion we get a ticket specifying a bearing problem, I think it more typical that we end up dealing with the bearings as part of another routine service, the front axle brake overhaul. Does this sound familiar?

With the customer’s car on the lift, I pull the wheels and calipers to gain access to the rotors. Oh, did I check the wheel for play while it was still attached? I pull the dust caps but they are a bit sticky. No problems, a little flat chisel and a hammer will knock them out. The edges are bent, but that shouldn’t keep me from putting them back on again. The cotter pin is removed and the castle nut follows. Next, I slide the disc toward me a bit to dislodge the outer bearing for removal. Darn, dropped it on the floor! I pick it up and place it on the lift arm so I won’t loose it again. Now I can put the wheel nut back on the spindle a few threads, and I’ll use it to pop the rear seal out, using the inner bearing as the seal driver! I set the rotor on the bench, and set the inner bearing on the lift arm with its mate.

With the rotors machined, I’m ready to reassemble. There’s still plenty of grease in the hub center and on the bearings, so I’ll just throw them back in, along with the old seal. I snug the wheel nut down on the washer, spin the wheel to see if it’s rotating free and shake the wheel to see if there is any play. No? Great, I’m done!

How many mistakes did you count in that little scenario? Now let’s revisit that and go over the way it should be done.

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