How to change wheel bearings

This is a straightforward job for anyone with a basic grasp of mechanics, and can save you a few quid as well. Here’s how to do it…

an you hear rumbling and grumbling coming from below? That could be the unmistakable sound of knackered wheel bearings. They’re hard working little blighters, taking care of some pretty big radial and axial loadings, so eventually their time will come.

Motorcycle wheel bearings are typically ball bearings consisting of inner and outer races, with balls rolling between them. The wheel bearing’s outer race is an interference fit in the hub, so the balls roll when the wheel turns and the other race has the wheel spindle going through it. 

The radius of the balls is the same as that of grooves in the bearing’s races. Deeper grooves mean that more of each ball is in contact with the races leading to better load distribution, and the balls and grooves also distort a little under load, reducing the pressure on a small contact area. This means that ball bearings do have some drag leading to their eventual wear. Wheel bearings use caged balls to keep them separate from each other, preventing the balls from bunching up.

Wheel bearing replacement is a job that’s well within the capabilities of the home mechanic, especially if you use the right tools. The other major benefit of tackling this task yourself is that you can save a few quid by getting hold of bearings from a local factor or online. They will usually also be able to supply any oil seals fitted to your wheels to protect the bearings from moisture and dirt.

What tools will I need?

Wood block. Hot-air gun. Brake cleaner. Seal remover. Steel rod to use as drift. Hammer or mallet. Seal and bearing drift.

How long will it take?

You’ll need around 15 minutes per wheel, not including removing them from and refitting them to the bike.

How much will it cost?

Your typical wheel bearing can be had for a fiver or so each and oil seals are approximately £3 to £5 each. So you’ll do it for £15 to £20 per wheel.

 

1. Hook out the old oil seals using the correct tool. These are widely available from tool and car parts shops for under a tenner, so there’s no excuse for trying to gouge them out with an old screwdriver. If you do that you’ll probably damage the seal housings in the process.

 

 2. In order to get the drift up against the bearings, the spacer between the two will have to be pushed slightly to one side – as you see it in the picture above. If it’s a bit tight then you’ll need to use either the drift itself or an old screwdriver or similar to lever it to one side.

 

3. Rest the centre of the wheel on a block of wood and drift out the bearing at the bottom of the hub as it rests on the block. Work around the circumference of the inner race with the drift. Once it’s moving, remove the block to let the bearing fall through.

 

4. Clean any old grease and corrosion from the bearing housing and inspect it for any damage which might’ve been caused by previous inept attempts at removing and fitting bearings. Dress any damage proud of the housing with light application of emery paper or similar.

 

5. The bearing you can see on the right in the picture above was removed from the wheel, whereas the one left is a new replacement. Note that both are 6202 type but the ones previously fitted were metal rather than rubber-sealed. There’s no real difference in practice.

 

6.  A gentle blast of warm air will help to expand the bearing housing slightly, thereby making it easier for the new ones to go in. Don’t go crazy or there’s a danger that you could end up damaging the finish on the hub. Make sure you direct the air to the inside of the housing.

 

7.  Next up it’s time to place the new bearing in the housing, ensuring that both are square to each other. If not then it will be difficult to get the bearing in, if it goes in at all – plus you risk damaging both the housing and the bearing, defeating the whole purpose of the exercise.

 

8. Use a proper aluminium bearing drift to drive the bearing fully home. These only cost around £20 for a set and are a far better bet than a socket as they are less likely to damage the bearing. Turn the wheel over, insert the spacer and then drive the other bearing in.

9. Insert replacement seals as you did with the bearings, and also use a proper drift to drive them home. If you used a socket here you would almost certainly damage the seal. That’s it. Job done. Time to refit the wheels and then roll along with silky smoothness. 

Words and photos Alan Seeley