How to inspect, install, adjust and upgrade steering head bearings

How to inspect, install, adjust and upgrade steering head bearings

How to inspect, install, adjust and upgrade steering head bearings

Steering head bearings, sometimes called steering neck bearings or headstock bearings, provide smooth, 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 may also swap the steering head bearings for a different size to accommodate a non-stock front end. A cruiser or chopper builder may also remove the bearings to install headstock rake cups, which allow for a few degrees of additional rake without cutting the frame. 

A home mechanic with some experience should have no problem replacing the steering head bearings with this guide and a few specialized tools. In addition to the common hand tools for removing the front end of the motorcycle, you'll need:

• A model-specific manual. This guide is intended only to assist you during your work.
• A way to lift and hold the front end firmly off the ground ( immense a front stand).
• A socket or wrench that fits the steering stem nut or bolt. Some motorcycles, such as the latest-generation Ducatis, may require a special tool.
• Bearing removal and installation tools. The bare minimum is a variety of hammers, drifts, and chisels. 
• A suitable waterproof grease. Check your manual for specifics. 
• A torque wrench.
• A little patience and a good long playlist.

If you're not confident in your ability to disassemble your front end, that's okay! Your local shop should be happy to help.

The basic steps for this work are:

1. Inspect the steering head bearings.
2. Remove the fork and other obstacles; remove the triple trees.
3. Replace the old bearings with new ones.
4. Replace the fork plates and adjust the wrench nut.
5. Replace the fork and anything else that has been moved to access the plates.
6. Check your work and go pedaling!

How do bearings fail? What are the symptoms of faulty steering bearings?

Steering head bearings are small but powerful. With proper adjustment and lubrication, they can last a long time. That said, we recommend checking them at the recommended service interval, usually found in your owner's manual. You should also check the steering head bearings if the front end feels uncomfortable. 

Dirt bikes and dual-sport bikes are particularly hard on steering head bearings. Bearings take a beating off-road, dirt gets in, and careless pressure washing leaches grease, drastically reducing bearing life. Repeated impacts from stunt riding can also quickly wear out steering head bearings. 

The most common symptoms of a faulty steering head bearing include poor steering feel, strange resistance, a rattling noise from the front end, or a notchy sensation, especially 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 70s KZ400, uses ball bearings. The steering system rides on small, greased steel balls. The balls move between two rings, called races. Each bearing has an inner and an outer race. The outer races fit in the steering tube, and the inner races fit in the steering stem. Ball bearings are common on older bikes like this KZ. Modern bikes with ball bearings usually have a cage that fits around the balls, rather than leaving them loose like older bikes.

The worn ball bearings in the KZ will be replaced with tapered roller bearings using a kit from All Balls Racing. This bearing design uses highly precise races and rollers, rather than balls. The tapered roller bearing's design makes it a good choice for the radial and axial requirements of the steering head. The bearing's inner ring, rollers, and retaining cage form a single assembly called the cone. The outer ring is called the cup. Like someone who can't decide how to eat ice cream, the cone goes into the cup. Most people simply call these parts the inner and outer races of the roller bearing, and I'll usually refer to them in this article as well, just to keep things simple.

Most modern motorcycles use caged ball bearings or tapered roller bearings. Not sure what type of bearings your bike uses? Look up a front-end parts diagram 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 the bearings as a unit and replace both bearings at the same time. Resist the temptation to replace only the inner races, leaving the old outer races in the steering head; the new parts will wear prematurely.

How do I lift my front wheel off the ground to inspect or replace my bearings?

This is a great question with multiple answers, because it depends on what you drive. Let's break it down by category.

Any motorcycle : Use a motorcycle lift . Another option is a small jack under the front of the frame, with a rear stand to support the rear. Front stands that hold the motorcycle by the head tube or wheel/fork/spool are not suitable for working on the steering head, as we must remove the entire front end.

Dirt bike : Use a dirt bike stand . Easy!

motorcycle with center stand : unfold the stand, then use a jack and a suitable block of wood to raise the front end.

Stunt Bike – Drain Fluids. Lay the bike on its side and do all the work on the ground. This probably isn't your first steering head bearing replacement.

Never work on a motorcycle that isn't securely fastened. Lifts, stands, jacks , and straps aren't that expensive. It's up to you to make sure you and your motorcycle are safe. Even a borrowed lift is better than MacGyvering something together, and this is from a huge MacGyver fan.

How to inspect motorcycle steering head bearings?

Raise the front wheel off the ground and disconnect the steering stabilizer if you're using one. The first test is to rotate the handlebars from one lock to the other. If the rotation feels notchy or snaggy, it's time to dig deeper. You should also check for resistance points. Make sure it's not a cable or hose rubbing against the fork. 

For another test, grasp the fork legs about halfway. Push and pull to feel for any play at the top. If you can hear the bearings clicking or feel any tilt, you need to adjust or replace them.

If your bike passes these tests and the bearings are lubricated, that's great! Get back on the bike and check them again. If your bike doesn't pass, you can try readjusting the bearings before diving into the deep end with a complete replacement. Keep your fingers crossed and skip to the adjustment section at the bottom of this article.

How to replace motorcycle steering head bearings?

As with any major job on your bike, you'll want a clean, clear workspace. Start by loosening some of the tighter nuts, like the axle nut and caliper mounting bolts. This will be much easier while the bike is still on the ground.

Then, get the front end airborne using your preferred method. I'll 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. Place a small piece of wood between the jack and the bike to prevent damage.

Remove the front wheel, fender, and brakes. If the brakes are too difficult to remove completely at this stage, unscrew the caliper(s) and master cylinder, then secure them with wire. Don't let them dangle from the hoses. It's never a bad idea to take photos to help with reassembly.

Remove the fork legs by loosening the upper and lower triple clamp mounting bolts. Be careful, a fork leg may slip under its own weight while unscrewing the mounting bolts, so be prepared.

From here on out, each bike will have its own order of operations for clearing the way for the forks, so be sure to follow the steps in your manual. Don't be afraid to tie up loose things!

In the case of the KZ, the upper triple clamp contains the indicators, ignition switch, and handlebars. It was easier to leave the ignition switch bolted to the triple clamp and simply disconnect the switch from the wiring harness. 

Loosen the steering knuckle nut or bolt and check for a washer underneath. You can protect the finish by placing a piece of paper towel over it before installing the socket or wrench. There's no guarantee, but it seems to help. Loosen the remaining upper triple clamp mounting bolts, and the triple clamp should slide off. Check for washers again.

The wrench nut is the final hurdle. Spray a little lubricant on the wrench nut threads and clean them with a cloth. This is usually a very fine step. If you can't loosen the wrench nut by hand, use a wrench or a tool specific to the model to loosen the nut. Some people use a hammer and a piece of soft metal, like aluminum or brass. There are even motorcycle Michelangelos out there who will do this whole bearing swapping with hammers and chisels. You'll often see their marks on a wrench nut.

As you turn the nut from the stem, place your other hand under the lower triple clamp to prevent it from falling. Remove the upper clamp while still supporting the lower clamp. 

If you have a bike with tapered roller bearings, set aside the upper seal and cone, then release the lower plate and steering stem. Unfortunately for those with ball bearings, the balls will likely fall out while you remove the triple tree, so use a rag to catch any strays.

The KZ bearings are toast! We remove the old race from the stem to make room for the new one. A special stem bearing removal tool, like the one from Motion Pro , is the easiest and best method. There's also a Harley-specific version.

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've seen roller bearings removed by cutting the cage with cutting pliers, removing the cage and rollers, and then removing the inner race by tapping a chisel against the exposed upper lip of the race. I prefer to try this method rather than inserting the chisel under the bearing, where it could easily damage the machined surface of the triple.

We remove the rings from the head tube. The best way to remove them is with a steering head puller . Grab the race and pull it out while tightening the puller. Another good option is a blind bearing remover and a slide hammer. Headset cup removers, available from most motorcycle tool suppliers, can also do the trick.

Michelangelo's bike will knock them out with a long slide. If you use this method, trim the end of your tool to a clean edge and slowly "walk" it outward, touching one side of the ring, then 180 degrees to the other side, then 90 degrees, and repeat. Don't always whine in the same spot without changing position. This can push the race into the frame, and with enough abuse, the fit will become too sloppy to hold the bearings. Then you have a big problem!

Installing the steering head bearings

Out with the old, in with the new. We install the new outer races in the head tube. Make sure the dirt and grease from the old bearings are removed. Good old Motion Pro has a brilliant steering head race driver that fits most tapered races. Another "pro" tool is a steering bearing press. There are several variations on the market, and they all work the same way. Alternatively, use the old race to insert the new one. Never hit a new bearing directly with a hammer. They hate it.

Keep tapping the race until you hear the sound change. You'll know when the race has stopped moving. Look around the edges of both seated races to make sure they're evenly positioned. Run a fingernail around the inside edge to feel for gaps.

We'll replace the steering stem components and then we can put this whole mess back together. For the ball bearings, take the lower race and guide it down. Ideally, you can secure it with a piece of tubing that barely slides over the stem. Don't use the old race to tap it in; it will get stuck! Michelangelo will use a hammer and several light taps all around the inside of the ring, right next to the stem. Once seated, apply a generous amount of grease to the races and use it to hold the balls in place. This may take a few tries. If your ball bearing kit came with cages, now is the time to install them. Lay out an old towel or T-shirt on the ground to catch any stray parts. Slide the stem up, insert the upper race, and hand-tighten the wrench nut to hold everything together. The worst is behind us now!

For tapered bearings, place the cone in your dominant hand and put a good blob of grease in your other palm. (You might want to wear gloves for this.) There are many great videos out there on 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 into the bearing and eventually out of the thin space at the back. A friend of mine says it's like the bearing is a chip, and grease is your favorite sauce. Load it up! Keep going until the grease has oozed all 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 lower seal in your kit and install it on the newly greased cone. Don't forget the seal! Slide the seal and cone down onto the stem, with the seal on the bottom and the cone's cone facing up. Insert the stem into the steerer tube, drop the upper cone and seal into place, and hand-tighten the wrench nut for now. Nice work!

How to adjust the steering head bearings on a motorcycle?

Adjusting the bearings is a breeze. The ideal fit is usually achieved by feel. You want it tight enough to have 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 wrench nut usually doesn't need to be very tight. Just focus on finding the perfect balance between zero slack and zero resistance. The steering action should feel buttery smooth now. If not, investigate. There could be dirt in the grease or a partially seated bearing.

It's time to button things up. Put the upper triple tree back in place. I usually slide the fork legs back through both triple trees to align them before tightening the upper nut to spec. Once finished, tighten the retaining bolts and install all the other components you removed. Check your work, as well as any other components you touched while replacing the bearings. Make sure all your controls still work. It's easy to forget a turn signal or horn cable. 

Thank you for your patience

I'm not going to sugarcoat it: this job isn't much fun. Your bike looks the same as when you started, and all that works is just getting things back to normal. These bearings are time-consuming, messy, and there are much more fun ways to spend an afternoon.

If you've made it this far, I think you deserve a little celebration. Steering head bearings are a crucial component that many cyclists overlook, so kudos to you for not caring about your bike.

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