How-To: Steering-Head Bearing Adjustment

Steering-head bearings don't attract much attention but you can at least give them a little bit

In the grand scheme of things, steering-head bearings don’t attract much attention. They don’t shine. They’re not loud, and they’re unlikely to cause any excitement when you troll Main Street on Saturday night. Unfortunately, they rarely receive what little attention they do need to do their job properly.

Consider this—everything that affects the fork and front tire passes directly through the steering-head bearings. That means inputs you make or ones you must react to are instantly affected by the condition of the bearings. If they’re loose, worn out or improperly adjusted, you’ve got problems. Depending on their health, those problems may range from a bike that’s hard to steer or wobbles at some particular speed to a motorcycle that turns into the world’s fastest shopping cart at the slightest provocation.

Steering-head bearing adjustment tools
It doesn't take much to adjust the steering-head bearings. From top left: The socket that fits the steering-stem locknut, the torque wrench, the hook wrenches, and the spring scale.Photography by Mark Zimmerman

In the bad old days of motorcycling, steering-head bearings demanded a fair amount of care. This was because the majority of motorcycles came equipped with loose ball, cup and cone steering-head bearings. The cup and cone bearings didn't offer the front end much support, and they tended to need fairly frequent adjustments. They also had to be disassembled, cleaned and repacked with fresh grease on a regular basis. To add insult to injury, they also wore out rather frequently.

Since the early 1980s every motorcycle worth the name has been delivered with tapered roller bearings in the steering head. Compared with cup and cone bearings, tapered roller bearings sustain a greater load, which improves handling and can take far more abuse, reducing maintenance chores. They can also be preloaded to a given torque setting, which makes the adjustment less of a “by guess and by golly” procedure. While the situation is now much improved, that doesn’t mean steering-head bearings can be completely ignored, no matter how hard you try.

give the forks a gentle tug to adjust steering-head bearings
With the front end clear of the ground, give the forks a gentle tug, If any motion is felt, the bearings are way too loose. (By the way, the shop towel is to protect the tank.)Photography by Mark Zimmerman

Bearing Inspection
Under normal riding conditions, tapered steering-head bearings seldom become loose enough to develop any measurable play. This is certainly true of most cruisers, which generally don't wheelie away from every red light, an action that pounds the crap out of bearings. For the most part the signs of out-of-adjustment steering-head bearings are relatively subtle. In many cases you may not realize they even need attention until the bike does something out of character to let you know. Lamentably, that something may have dire consequences for both you and your bike.

By far the most common symptom of loose steering-head bearings is the classic front fork shake when decelerating from approximately 45 to 35 mph, usually when you've got a relaxed grip on the handlebars. Of course, other problems can create front-end wobbles. But if no obvious cause is forthcoming, suspect the steering-head adjustment. Loose steering-head bearings can also cause the bike to feel "sloppy" or vague at high speeds or, in some instances, create high-speed wobbles.

For the most part bearing- adjustment problems will be confined to “too loose” situations. Overtightened steering heads do cause problems. In fact, overly tight steering-head bearings are worse than ones that are a bit loose, but because overly tight bearings are caused by improper adjustment, and you’re going to learn the correct method of adjusting bearings, overtightening shouldn’t be an issue.

Make sure the forks are free to turn when you make steering-head bearing adjustments
Make certain that the forks are free to turn. If the bearings feel notched or dented, they'll need to be replaced.Photography by Mark Zimmerman

In some cases your shop manual will provide a torque figure for the steering-head bearing adjuster nut. In a perfect world, applying the correct torque to the nut should preload the bearings to the proper setting. The problem is that to access the nut, which is most likely castellated and requires a special socket, you’ll either need to remove the top clamp or come up with the right adapter (available for limited models) that allows you to use a torque wrench on the nut without removing the clamp. A few problems present themselves at this point. First, not all manufacturers provide preload specifications. Second, assuming you do have the specs you need, but can’t come up with the right adapter, removing the top clamp complicates a relatively minor adjustment procedure to the point where it becomes a real headache. What follows are the most practical real-world methods of checking and adjusting steering-head bearings.

Raise the front end clear of the ground. Make certain that the control cables aren’t binding the forks, and that no accessories impede the fork’s ability to turn freely. With the wheel in the straight-ahead position, check the bearings for play by grasping the lower fork legs as close to the axle as possible and giving them a push and a pull. If any play is felt, the bearings definitely need adjusting, as does your maintenance program. No play? Good, gently turn the bars from side to side. The forks should move smoothly without binding in any position. If the bearings feel like there is a notch or dent in them, they’ll need to be replaced ASAP. Typically, the dent will be most apparent in the straight-ahead position; in a worst-case scenario, the bearings will actually feel as if they’re dropping into a detented position.

Use your torque wrench to measure the fall-away for steering-head bearing maintenance
Use your torque wrench to measure the fall-away. In this case it was measured from dead center.Photography by Mark Zimmerman

To determine if the steering-head bearings are correctly tensioned, we’ll need to measure the amount of effort it takes to turn the fork. This may be called “fall-away,” or “turning effort,” and it’s always measured with the front wheel off the ground.

In some cases the service manual will specify that it should take X amount of torque to turn the fork, commonly two to four foot-pounds. The procedure is simple: Place the appropriate socket over the steering-stem locknut. Using a beam or dial-type torque wrench, measure the amount of effort it takes to turn the fork from point A (normally full lock or some position close to it) to point B (normally the straight-ahead position). The only problem with this method is that not all manuals provide the torque figure you’ll need to measure the fall-away, though in my experience approximately two to four foot-pounds should get you in the ballpark.

You can also use a spring scale when making steering-head bearing adjustments
As an alternative, a spring scale can be used. Again, start with the forks in the straight-ahead position.Photography by Mark Zimmerman

Provided your manual lists a bearing preload specification, there is an alternative. If you know what the bearing preload is supposed to be, you can use a spring scale and some simple math to figure out if the bearings are still in adjustment. The formula is simple. The turning effort—call it Measurement (in pounds)—equals the bearing Preload (in inch-pounds) divided by the Distance (in inches) from the center of the steering stem to the center of one fork tube. Or M = P divided by D. For example, if the manual tells you that the bearing preload adjuster should be tightened to 13 inch-pounds, and you know that the distance between the steering-stem center and the fork tube center is three inches, you can find the turning effort by using the formula. Since 13 divided by 3 equals 4.3, it should take 4.3 pounds to move the fork.

To check the preload, attach the spring scale (available at fishing tackle shops and hardware stores) to the fork tube just below the bottom clamp. Place the fork in the straight-ahead position. Holding the scale at 90 degrees to the steering stem, pull gently while reading the scale until the fork begins to move. Compare the reading on the scale to your calculations and adjust the preload accordingly. The beauty of this method is that you only need to know the specified bearing preload and some basic math to determine if your bearings are correctly adjusted.

Loosen the steering-stem locknut and the fork-tube pinch bolts on the lower clamp for steering-head bearing adjustment
Loosen the steering-stem locknut and the fork-tube pinch bolts on the lower clamp (not shown).Photography by Mark Zimmerman

Unfortunately, some manuals don’t provide any figures, indicating only that the fork must be free to turn smoothly with a minimum of preload, or in some cases that the fork should fall away by some predetermined amount or distance.

If for whatever reason you can’t measure the preload formally, you’ll have to do it the old-fashioned way. Admittedly, this method is somewhat subjective and depends on a fair amount of “Kentucky Windage,” but rest assured, it works just fine.

Position the fork in the straight-ahead position, then let go of the bars. If the fork swings to full lock like a dropped rock, the bearings are on the loose side. If it takes a gentle nudge to move the forks off-center, the bearing adjustment is on the money or close to it. If you have to push the fork over, or it stays in any one position, particularly one between straight-ahead and full lock, the bearings may be on the tight side, though some manufacturers do call for a slightly stiff preload, so check your service manual before jumping to any conclusions.

Most steering-head bearing adjusting nuts are castellated.
Most steering-head bearing adjusting nuts are castellated.Photography by Mark Zimmerman

Bearing Adjustment
To adjust the preload you'll need to first loosen the fork-tube pinch bolts at the lower clamp. This allows the tubes to move slightly in the clamp as the adjusting nut on the steering stem is tightened. Next, loosen the locknut on the steering stem. This may mean removing the handlebars. If so, you might want to mark their position so they can be reinstalled in the same spot. Once the locknut is loose, use the appropriate tool to turn the adjusting nut. If the correct tool isn't available or you just like doing things crudely, a hammer and punch will work fine. If the nut is noticeably loose, tighten it down gently until you start to feel some resistance, then give it another one-eighth turn.

Once you’re happy with the preload adjustment, torque the steering-stem locknut to the recommended specification. Tightening the locknut may increase the overall preload beyond what’s acceptable. In that case, simply back off the adjusting nut slightly, then retorque the locknut. It may take a few shots to get it perfect; it always does for me, and I’ve been at it a long time.

Use the appropriate wrench to make a steering-head bearing maintenance
Use the appropriate wrench to adjust the locknut one-eighth turn at a time until the adjustment is correct. Recheck your fall-away only after the top nut has been torqued down.Photography by Mark Zimmerman

Make sure all the nuts and bolts are tight, and recheck your fall-away before road testing the bike. If the bike still feels loose or the bars oscillate during deceleration, the bearings may need a bit more preload. Try tightening the bearing adjuster by one-eighth turn at a time and see if the situation improves. If the bike "wanders," that is, becomes hard to steer and seems to need constant correction, particularly at moderate speeds, or the steering feels stiff, then the bearings are too tight and should be backed off one-eighth turn until the bike feels better. Bear in mind that overtightening the adjuster nut can put several tons of pressure on the bearings, which will ruin them in short order. If there is any doubt as to the adjustment, it's better to err toward the slightly loose side than the overly tight side.

Initially, the steering-head bearing adjustment procedure may seem a bit tedious. By its nature this type of work depends to a large extent on "feel," which always takes some time to develop. But stick with it; the end result will be a better-handling, safer motorcycle.