® Steering Bearings

There is a lot of misinformation on the 'net regarding motorcycle steering bearings. Forums by and large propose that fitting tapered bearings to bikes originally equipped with ball type is essential, and all kinds of steering bearing adjustment routines have been put forth, many of them wholly inadequate. Further, removal and replacement techniques are posted that should make one cringe, they are so cave-manish.

Professional powersports techs have long known the truth, that properly installed and maintained ball type steering bearings are just as worthy as their tapered counterparts. True, tapered steering bearings technically are capable of high loading, but this is small advantage on vehicles weighing as little as most motorcycles do, even today. Tapered bearings also indent their races less readily than do ball type. Ball type steering bearings are almost famous for developing that "auto pilot" straight-ahead notch, whereas tapered ones are much more resistant to doing that. But the ball type notch really only happens when maintenance has been ignored. If maintained properly, both ball and tapered have their place, and both are equally viable.

There is one outcome of ill-maintained steering bearings, of whichever type, that shows itself pretty plainly, and that is what I once termed the helmet strap wobble, more commonly known as the decel wobble. When taking one hand off the bars to check the helmet strap, or simply, with both hands, decelerating from somewhat over 50 mph rapidly downward in speed, the front fork shakes back and forth. Though the usual assortment of tire, suspension and wheel issues (including alignment) shouldn't be overlooked, this is almost always due to a steering bearing problem. Read my article on the classic decel wobble problem for details, but for now just realize it is a specific issue with a specific solution, and has nothing to do with steering bearing tension, despite the fact that many shops seek to cure it by simply tightening the bearings. Unfortunately, it's not that simple.

One thing many are not aware of is just how far motorcycle manufacturers have progressed in describing proper steering bearing maintenance. From the early days' laughable recommendation to inspect for bearing issues by blocking up the front end and pulling and pushing on the fork, to later "common wisdom" parotting of the technique of simply taking out all free play but allowing unhindered movement -- all of this and more is history and should be relegated to the same scientific wasteland as the notion of spontaneous generation. BMW began to rise from this technological swamp with their technique of torquing the adjustment nut, but it was Honda who really raised the bar with their spring scale method, beginning in about the mid 1980s. Again, see the decel wobble article for details, but essentially the spring scale method quantifies the amount of drag that the fork exhibits. That's right, the fork is not, contrary to so much that has been said on the web, supposed to simply flop about freely from stop to stop. The exact spring scale detemined tension in pounds for each application needs to be worked out by trial and error, but some hard facts do indeed exist to guide you. See the article. I don't believe a blanket recommendation or corelation can be made between tensioning nut torque and spring scale reading, except by trial and error, and then only on a particular, one-to-one basis. That is, on your bike, with your accessories, etc. I have found that even clutch cable routing affects the reading, which should not surprise us.

Speaking of using a torque wrench, it's a good idea, but avoid believing that it is the end of adjustment. Instead, it's only the beginning. Though it may seem intuitive to simply tighten the steering bearing tension nut to a given torque, in reality a spring scale measurement of the actual fork drag is far more real-world and thus the only way to accurate predict how a fork will feel in use. And, better than the jack-it-up-and-grab-it test for a fork whose bearings are thought to be too loose is to lay your fingers over the span between fork top bridge and the exposed part of the frame, then with the front brake on, shift your weight forward and back repeatedly to load and unload this point. Any fore and aft movement is easily picked up by your fingers, and will indicate loose steering bearings, but really only ones that are very very loose, as opposed to ones that are simply looser than ideal. As for removal and replacement, though at one time only the OEMs supplied the special tools that enable doing this job properly, the aftermarket has in recent years caught up and now offers similar, comparable tools. So there is no excuse for not doing this correctly.

A look at the recommended service intervals and what is to be done (in your owner's manual) will undoubtedly show that the bearings are to be inspected and adjusted as necessary, so again, there is no excuse for it being overlooked. I know, dealers don't follow the owner's manual's maintenance table, and even if they did they may not be aware of the seat-then-adjust methodology, but they should be, and it's your job to hold their feet to the fire, if not actually educate them too.

In summary, ball and tapered both are good bearings. As has always been the case with powersports vehicles, what is far more at stake is maintenance. It's a lot like the oil topic on forums. What (kind) is no where near as important as how (often, technique, procedure).

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