Motorcycle Steering Head Bearing Maintenance
March 24, 2009 by jesrod
Filed under Harley, How To, Motorcycle Steering Head Bearing Maintenance
Aside perhaps from tires, no other component affects your motorcycle’s steering and handling more than the bearings inside the bike’s steering head, where the fork meets the frame. Ignore them at your own risk. Read on to learn how to get at, service, grease, and, if necessary, replace them.
Be honest, when’s the last time you serviced your bike’s steering-head bearings? Never? No surprise there. I’d bet good money a fair percentage of riders don’t even know they need maintenance, let alone perform any on a regular basis. But consider this: Few other components have as much influence over the way your bike steers and handles. Every steering input you make or receive passes directly through those bearings. Ignore them if you want, but when your formerly sweet-steering bike starts handling like a piece of agricultural equipment, don’t say we didn’t warn you.
What Happens?
When your new bike was assembled, its steering-head bearings were slathered with nice, fresh grease. The grease lubricates the bearings, acts as a cushion between the bearing rollers and their races and prevents corrosion damage. Over time, and helped along by repeated hot water/high pressure washings at the local quickie-wash, the grease tends to dry up (or be washed out). As soon as the grease is gone or rendered useless by old age, the bearing rollers stop rotating and start skidding. Once that happens, it’s only a matter of time before the bearings are dented, the steering notchy and vague and the handling foul.
Because this process normally takes several years or more to occur, the average rider adapts to the situation and is usually unaware that anything’s amiss until someone else points it out to him or major damage has been done. To prevent premature bearing wear and the unpleasantness that accompanies it, your motorcycle’s manufacturer would like you to remove, clean and repack the steering-head bearings on a periodic basis. Since intervals vary greatly among manufacturers, you’ll need to consult your owner’s manual for the details, but typically they’d like you to inspect the bearings every two to four years or at some prescribed and fairly high mileage.
Now You Know
Now that you know the score, you’ve got three options. You can do nothing and replace the bearings when they fail, an alternative chosen by a surprising number of riders. You can opt to have the dealer service them for you, which is certainly an acceptable route, or you can do it yourself.
Before you decide, let me warn you that servicing your bike’s steering-head bearings is neither a particularly quick job nor a very interesting one. On the plus side, there’s some heavy lifting involved, and you’ll probably get good and greasy before it’s done. Still with me? Good. A little mechanical interaction between you and your bike is always a good thing.
While the thought of performing a front fork-dectomy may seem a little daunting the first time, the procedure is very straightforward, so don’t let the seeming complexity put you off. Besides, one of the nice things about this job is that there’s no real imperative to do it quickly. Frankly, there’s not much point in doing it in August when your bike hits exactly 30,000 miles or waiting until February when the bike has 35,000 miles on it and is going to be off the road anyway. My recommendation is to schedule this one along with your regular yearly major service, or to incorporate it along with all those other jobs you’ve been putting off for the last few years, like replacing that leaky fork seal or worn-out front tire.
In the main, this is a routine job. However, there is one aspect that can create a real cramp. All motorcycles manufactured since the early 1980s use tapered roller steering-head bearings, the lower stem bearing normally being press-fit onto the steering stem. To properly grease the lower bearing, it should be removed from the stem. Fifty percent of the time they slide right off. But the other 50 percent can be a bear to remove. While there are techniques to remove stubborn bearings without using any special tools, they take time and experience to acquire, and the end result is just as likely to be a damaged bearing as a good one. If yours is one of those that just won’t budge, my suggestion is to farm out its removal, repacking and replacement to your local motorcycle or automotive machine shop, but find out beforehand how they plan to do the job. If they tell you they’re going to chisel or burn it off, find another shop. Lastly, though I don’t condone it, some bearings can be cleaned and repacked without removing them from the stem. In some cases this may be the most practical solution.
It Takes How long?
A full steering-head service—removing, cleaning, inspecting and repacking the bearings—normally takes an experienced tech anywhere from two to eight hours depending on the type of bike the available facilities, and level of ambition. Since I’m assuming this is your first ride on this particular merry-go-round, plan on spending at least a day, start to finish. I’d also suggest taking a look at the recommended tools list before you get in too deep. There’s nothing more frustrating than stopping in the middle of a job because you don’t have some crucial tool or part.
Tools & Supplies
Here is a typical list of the unique tools and supplies you will need to service your motorcycle’s steering-head bearings. You shop manual may mention some additional items that you’ll need.
Get your bike on a work stand or centerstand with the front end off the floor. Start by removing anything that doesn’t look like a triple clamp. Your shop manual will detail the exact procedure. Resist the temptation to short-cut the job by removing some of the subassemblies in large chunks. Wrestling with the forks while they’re still attached to the front wheel and fender isn’t nearly as much fun as you’d think. Before loosening the top clamp’s retaining nut, rotate the clamp from stop to stop. Without the weight of the front-end assembly on it, any roughness or dents in the bearings will feel much more obvious. If there’s any doubt, now’s the time to replace the bearings.
Remove the upper clamp; you may need to persuade it off with a plastic mallet. Remove the preload adjusting nut(s) from the stem; this particular one was castellated, which requires a hook spanner—or a hammer and punch if you don’t care what the nut looks like when you’re done—to remove and replace it. As you loosen the nut, the stem should drop down, so be ready for it. If it’s sticky, thread the nut back onto the first few threads of the stem (to protect them from damage), then give the stem a light tap with your plastic hammer. It should drop right out.
Remove the upper bearing and set it aside. As a rule, the upper and lower bearings have different internal diameters, so there’s no chance of mixing them up, but just to be safe, you may want to mark them as they’re removed to prevent confusion down the road. Give both races a thorough cleaning and inspect them for nicks, dents, pits or any other damage. By themselves the dark lines (shown) are nothing to worry about. However, they may hide other problems. Run the tip of your finger or fingernail around the races. If you feel anything other than a perfect surface, the bearings and races should be replaced. If this turns out to be the case, your manual will detail removing and replacing the steering-head races.
The Tricky Part
Here’s the trickiest part of the job. Clamp the steering stem into a soft jawed vise and pry the lower bearing off the stem (use a piece of cardboard or wood to protect the stem). If she won’t budge, you can try a little heat, but be careful—getting splashed with hot grease isn’t much fun, and some bearings use easily melted plastic cages to position the rollers. Use your best judgment here. If things are going badly, you may want to farm this part of the job out or consider repacking the bearing in place. If you don’t have access to a solvent tank, you can clean the bearings using an aerosol degreaser. Brake clean works just fine on a soft bristle brush or old toothbrush. The bearing should be allowed to air dry or wiped clean with a soft rag. If you use compressed air to dry them, blow the air into the bearings parallel to the roller. Whatever you do, don’t spin the bearing with the air. It may be fun to hear it sing, but spooling one up ruins it before you can say, “Bob’s yer uncle.”
Your local auto supply or tool junkie can sell you all sorts of bearing packing devices, but these lack the personal touch and waste a lot of grease. Here’s the way it should be done. Place a healthy dob of grease in the palm of your left hand. Hold the clean bearing in your right hand, with the large diameter side facing the grease (if the bearing is a ball or non-tapered roller bearing, it can be packed from either side). Draw the bearing across your palm as if you were using it to scrape the grease out of your hand, rotating it as each segment becomes fully packed. When it’s done correctly you’ll see curls of fresh grease rolling out of the small end of the bearing. It may take a few swipes to get the hang of it, but I’ve packed thousands of bearings this way and never had one fail.
All Together Now
If the lower bearing came off particularly hard, place the stem in the freezer for a few hours to shrink it. Keep the bearing at room temperature or above, just not so far above that it melts the grease. It’ll also help to polish the lower portion of the stem where the bearing sits. Use a piece of emery paper and go lightly. The object isn’t to remove lots of metal, just to clean up the area and remove any burrs. Install the dust seal and slide the greased bearing onto the stem. Position the bearing driver or hunk of pipe over the bearing, making absolutely certain it’s only contacting the inner race, then drive the bearing onto the shaft. There’s no need to beat the snot out of it—a few stout blows ought to do it. As the bearing seats the tone of the hammer will change. That’s your signal to stop. As shown in the photo, I’ve had some success using a piece of heavy PVC pipe and a composite hammer to reinstall the bearing. This works fine if the bearing is a light press onto the shaft.
Give both races a swipe of grease and slide the steering stem up through the neck. Slide the upper bearing onto the stem, followed by any dust seals. Run the preload adjuster down finger-tight.
The bearings must be preloaded to the manufacturer’s specifications. In some cases that means tightening the nut to some initial torque, backing it off and then resetting it to the suggested preload. If no specs are provided or they seem vague, you’ll need to use a little Kentucky Windage. Using moderate pressure, bottom the adjusting nut until the stem starts to bind. Rotate the steering stem back and forth a few times, then back the nut off half a turn. Repeat the tighten, turn, loosen cycle several times, always turning the steering stem from side to side. For the final adjustment, draw the nut up snugly and then back it off a turn. Don’t be too concerned if the stem feels a little tight at this point—it’ll free up as you install the rest of the front-end parts.
Install the top clamp and snug, but don’t tighten, down the top nut. Slide the fork tubes into the clamp, positioning them where you want them. Tighten only the lower clamp pinch bolts. Insert the front axle, making certain it slides smoothly into place. If it doesn’t, check the fork tube height and alignment. A little extra time spent getting these adjustments spot-on will eliminate a lot of fork stiction and pay big dividends in the comfort and handling departments.
Adhering to the manufacturer’s recommended torque settings, tighten the top clamp nut first. This will ensure it’s fully seated on the steering stem, followed by the upper and lower pinch bolts. From here on in it’s just a straightforward reassembly job, followed by a road test.
Back on the Road
