Hidden away between the triple trees, your steering head bearings probably aren’t something you think about much, even though you use them every time you ride.
Steering head bearings, sometimes called steering neck bearings or headstock bearings, provide smooth and stable steering for the front end… as long as they’re in good condition. These bearings will need to be replaced once they’re worn. Custom builders might also swap steering head bearings for a different size to adapt a non-stock front end. A cruiser or chopper builder could also remove the bearings to install neck rake cups, which allow a few extra degrees of rake without cutting the frame.
A home mechanic with some experience should have no trouble replacing steering head bearings with this guide and some specific tools. In addition to common hand tools for disassembling the front of your bike, you’ll need:
- A model-specific manual. This guide is only meant to help you through the job.
- Some way of securely lifting and holding the front end off the ground (not a front stand).
- A socket or wrench that fits the steering stem nut or bolt. Some bikes, like late-model Ducatis, may need a special tool.
- Tools to remove the bearings, and tools to install the bearings. Bare minimum is a variety of hammers, drifts, and chisels.
- A suitable water-resistant grease. Check your manual for any specifics.
- A torque wrench.
- Some patience and a good long playlist.
If you’re not confident in your ability to take your front end apart, that’s OK! Your local shop should be happy to help you out.
The basic steps to this job are:
- Inspect steering head bearings.
- Remove fork and other obstacles; remove the triple trees.
- Swap old bearings for new ones.
- Replace triple trees and adjust spanner nut.
- Replace fork and whatever else was moved to access the triple trees.
- Check your work and go ride!
How do the bearings fail? What are the symptoms of bad steering head bearings?
Steering head bearings are small but mighty. With proper adjustment and lubrication, they can last a long time. That said, you’ll want to check in on them at the recommended service interval, usually found in your manual. You should also check your steering head bearings if the front end doesn’t feel right.
Dirt bikes and dual-sports are especially hard on their steering head bearings. The bearings take a beating off-road, dirt creeps in, and careless pressure washing blows their grease out, all dramatically shortening the bearings’ lifespan. Repeated impacts from stunting can also wear out steering head bearings in a hurry.
Common symptoms of bad steering head bearings include poor steering feel, strange resistance, clunking from the front end, or a notchy feeling, particularly when pointing the front wheel straight ahead. In extreme cases, there will be visible and audible play.
Ball bearings versus tapered roller bearings
The bike we'll be working on today, a late-1970s KZ400, uses ball bearings. The steering rides on small steel balls in grease. The balls move between two rings, called races. Each bearing has an inner and outer race. The outer races live in the steerer tube, and the inner races fit onto the steering stem. Ball bearings are common on older bikes like this KZ. Modern bikes with ball bearings usually have a cage that fits over the balls, rather than leaving them loose like older bikes.
The KZ’s worn ball bearings will be swapped for tapered roller bearings, using a kit from All Balls Racing. This bearing design uses rings and rollers of very high precision, rather than balls. The tapered roller bearing’s design makes it a good choice for the steering head’s radial and axial demands. The bearing’s inner ring, rollers, and retaining cage are an assembly called the cone. The outer ring is called the cup. Like someone who can’t decide how they want to eat their ice cream, the cone goes in the cup. Most people just call these parts the inner race and the outer race of the roller bearing, and I'll usually call them that in this article, too, just to keep things simple.
Most modern motorcycles use caged ball bearings or tapered roller bearings. Not sure which kind of bearings your motorcycle uses? Look up a parts diagram of the front end, and you’ll see exactly what your bike had from the factory without turning a single wrench. Regardless of what your bike uses, always replace bearings as a unit, and replace both bearings at the same time. Resist the urge to only replace the inner races, leaving the old outer races in the steering head, The new parts will wear prematurely.
How do I get my front wheel off the ground to inspect or replace my bearings?
That’s a great question with several answers, because it depends what you ride. Let’s break it down by category.
Any bike: Use a motorcycle lift. Another option is a small jack under the front of the frame, with a rear stand to support the back. Front stands that hold the bike by the steering head tube or the wheel/fork/spools are no good for steering head work since we have to remove the entire front end.
Dirt bike: Use a dirt bike stand. Easy!
Bike with a center stand: Deploy the stand, then use a jack and a suitable block of wood to lift the front.
Stunt bike - Drain fluids. Lay the bike on its side and do the whole job on the ground. This probably isn’t your first steering head bearing replacement.
Never work on a motorcycle that isn’t safely secured. Lifts, stands, jacks, and straps are not that expensive. It’s up to you to make sure that you and your bike stay safe. Even a borrowed lift is better than MacGyvering something together, and that’s coming from a big MacGyver fan.
How to inspect motorcycle steering head bearings
Get that front wheel off the ground, and disconnect the steering stabilizer if you’re using one. The first test is to turn the handlebars from lock to lock. If the turn feels notchy or grindy, it’s time to dig deeper. Points of resistance should also be investigated. Make sure it’s not a cable or hose rubbing against the fork.
For another test, grip the fork legs about halfway up. Push and pull to feel for any play up top. If you can hear the bearings clicking, or feel slop, you need to adjust or replace.
If your bike passes these tests and the bearings are lubricated, that’s great! Get back to riding and check them again some other time. If your bike did not pass, you can try readjusting the bearings before jumping into the deep end with a full replacement. Cross your fingers and skip down to the adjusting section at the bottom of this article.
How to replace motorcycle steering head bearings
As with any important job on your bike, you’ll want a clean and clear workspace. Start by breaking some of the tighter nuts loose, like the axle nut and the caliper mount bolts. It’ll be a lot easier while the bike’s still on the ground.
Next, get the front end in the air using your method of choice. I'd have to remove the aftermarket pipes on the KZ to use my motorcycle lift, so I’m just using a rear stand and a small floor jack instead. Slip a small piece of wood between the jack and your bike to prevent damage.
Remove the front wheel, fender, and brakes. If the brakes are too difficult to fully remove at this stage, unbolt the caliper(s) and master cylinder, then tie them out of the way with wire. Don’t leave them dangling by their hoses. It’s never a bad idea to take pictures as you go to help with reassembly.
Remove the fork legs by loosening the upper and lower triple tree pinch bolts. Careful, a fork leg might slip out from its own weight as you undo the pinch bolts, so be ready.
From here on, every bike will have its own order of operations to clear the way for the triple trees, so make sure to follow the steps in your manual. Don’t be afraid to zip-tie disconnected stuff out of the way!
In the KZ’s case, the upper triple holds the gauges, the ignition switch, and the handlebar. It was easiest to leave the ignition switch bolted to the triple and simply unplug the switch from the harness.
Undo the steering stem nut or bolt, and check for a washer under it. You can protect the finish by putting a piece of paper towel over it before fitting the socket or wrench. No guarantees, but it seems to help. Loosen the remaining upper triple clamp pinch bolts, and the triple should slide right off. Check again for washers.
The spanner nut is the last thing in the way. Spray a little lubricant on the spanner nut threads and wipe them clean with a cloth. They’re usually a very fine pitch. If you can’t loosen the spanner nut by hand, use a spanner wrench or a model-specific tool to loosen the nut. Some knock it loose with a mallet and piece of soft metal, like aluminum or brass. There are also the motorcycle Michelangelos out there who'll do this whole bearing swap with hammers and chisels. You’ll often see their marks on a spanner nut.
As you spin the nut off the stem, place your other hand under the lower triple to prevent it from falling. Remove the upper triple tree while continuing to support the lower.
If you have a bike with tapered roller bearings, set aside the upper seal and cone, and then drop the lower triple and steering stem out. Unfortunately for the ball bearing folks, the balls will probably want to fall out as you remove the triples, so use a rag to catch any runaways.
The KZ’s bearings are toast! Let’s take the old race off the stem to make way for the new one. A special stem bearing removal tool, like Motion Pro’s, is the easiest and best method. There's also a Harley-specific version.
The Michelangelos will use hammers and a variety of chisels to gently tap around the edge of the bearing until it comes free. Work carefully to avoid damaging the stem. I have seen roller bearings removed by snipping the cage off with cutting pliers, removing the cage and rollers, then driving the inner race off by tapping a chisel against the race’s exposed upper lip. I’d rather try that method than inserting the chisel below the bearing, where it could easily damage the triple's machined surface.
Let’s get the rings out of the steering tube. The best way to remove these is with a steering head race puller. It grips the race and extracts it as you crank the puller tighter. Another good option is a blind bearing removal collet and a slide hammer. Headset cup removers, available from most bicycle tool suppliers, can also do the trick.
Motorcycle Michelangelo will knock them out with a long drift. If you use this method, dress the end of your tool for a clean edge, and slowly “walk” the ring out by tapping one side of the ring, then 180 degrees away on the other side, then 90 degrees away, and repeat. Don’t wail on the same spot over and over without switching positions. That can push the race into the frame, and with enough abuse, the fit will become too sloppy to hold bearings. Then you have a big problem!
Installing steering head bearings
Out with the old, in with the new. Let’s install the new outer races into the steering tube. Make sure the crud and grease from the old bearings has been wiped away. Good old Motion Pro has a slick steering head race driver that fits most tapered races. Another "pro" tool is a steering head bearing press. There are several variations on the market, and they all work about the same. Alternatively, use the old race to tap the new one in. Never strike a new bearing directly with a hammer. They hate that.
Continue tapping the race in until you hear the sound change. You’ll feel when the race doesn’t go in any farther. Look around the edges of both seated races to make sure they’re positioned evenly. Run a fingernail around the inside edge to feel for gaps.
Let’s replace the components on the steering stem, and then we can put this whole mess back together. For ball bearings, take the lower race and drive it down. Ideally, you can tap it into place with length of pipe that barely slips over the stem. Don’t use the old race to tap for this job; it’ll get stuck! Michelangelo will use a hammer and lots of light taps all around the inside of the ring, right next to the stem. Once you've got it seated, apply a liberal amount of grease to the races and use it to hold the balls in place. This might take a few tries. If your ball bearing kit comes with cages, now’s the time to install them. Lay an old towel or shirt on the ground to catch any runaways. Slide the stem up, pop the top race on, and hand-tighten the spanner nut to hold everything together. The worst is behind you now!
For tapered bearings, put the cone in your dominant hand, and put a nice dab of grease in your other palm. (Might want to wear gloves for this.) There are lots of great videos out there for how to pack a bearing, but here are the basics. Push the larger side of the bearing into the grease and drag it across your palm. You’re pushing grease up into the bearing and eventually out the thin gap in the back. A friend of mine says it’s like the bearing is a chip, and the grease is your favorite dip. Load it up! Keep going until grease has oozed through all the way around. Special bearing packing tools, like the Lisle 34550, can automatically pack a roller bearing. Repeat the greasing process for the other cone.
Find the correct bottom seal in your kit, and fit it to the freshly greased cone. Do not forget the seal! Slide the seal and cone down onto the stem, with the seal at the bottom, and the taper of the cone pointing upwards. Insert the stem into the steering tube, drop the top cone and seal into place, and hand-tighten the spanner nut for now. Nice work!
How to adjust motorcycle steering head bearings
Adjusting the bearings is super simple. The ideal adjustment is usually reached by feel. You want it tight enough that there’s no play, but not so tight that you start to feel resistance in the steering. It’ll take some trial and error. And put down the hammers, Michelangelo. That spanner nut usually doesn’t need to be very tight. Just focus on finding that perfect balance of zero slop and zero resistance. You should feel buttery-smooth steering action now. If not, investigate. There could be crud in your grease or a partially seated bearing.
Time to button things back up. Place the top triple tree back in its place. I typically slide the fork legs back through both triples to align them before torquing the top nut to spec. Torque the pinch bolts when you’re done, and install any other components you removed. Check over your work, as well as any of the other components you touched while changing out the bearings. Make sure all your controls still function. It’s easy to forget a turn signal or horn wire.
Thanks for bearing with me
I’m not going to sugarcoat it: This job isn’t much fun. Your bike looks exactly the same as when you started, and all that work is just to get things back to normal. These bearings take a while, they’re messy, and there are far more enjoyable ways to spend an afternoon.
If you made it this far, I think that deserves some celebration. Steering head bearings are a critical component that so many riders overlook, so kudos to you for giving a damn about your bike.