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Do your wheel bearings need replacing?
Odds are that few motorists will ever hear of wheel bearings until their mechanic suggests that theirs need replacing. Like the wheels themselves, they’re components we completely take for granted and we rarely consider that they might need replacement at some stage. Nonetheless, they’re rather important, so don’t ignore the mechanic’s warning.
First up: what are wheel bearings?
Well, they’re bearings. For the wheels. Ok, that much is obvious so let’s go a little more in depth. The wheels themselves usually bolt onto a wheel hub and at the centre of that, allowing the wheel to rotate in a smooth friction-free manner is where you’ll find the wheel bearings. There are different styles and designs of bearings, but most road car wheel bearings are made up of a set of spherical steel balls held in line by a metal track called a race.
Here’s a few common wheel bearing types:
Sometimes there are two lines of ball bearings (called sets), with multiple ‘races’ between them. The whole lot is usually sealed up with high-temperature grease within and these days it’s not often a serviceable component, so when it gets noisy it has to be replaced. It’s all supplied as a single component that is pressed into the hub itself. The fit is so tight that there’s no chance of it popping out, but there’s usually a circlip in front of the bearing in any case. Sometimes, it’s necessary to replace the whole wheel hub and not just the bearing.
How to tell if your wheel bearings need replacement.
In honesty, it’s very difficult for the average driver to tell when a wheel bearing starts to fail. The noise it makes starts out quietly, though the longer it’s left, the louder it becomes. It’s best described as a whirring, droning sound in the distance when the car is on the move and the faster you drive the louder it should become. It may also be accompanied by a slight vibration….but it might not!
Annoyingly, that’s only half the job. It’s notoriously difficult to work out which of the four wheel bearings is making the noise. Even seasoned mechanics can find it tricky as the sound can echo through the car. The only sure way to identify the culprit is to jack the car up and manually rotate the wheels, first of all listening for one wheel that sounds different from the rest when it rotates, secondly you’d check for play in the wheel bearing (side-to-side movement of the wheel)
Buying wheel bearings.
Thankfully wheel bearings or wheel bearing kits are generally speaking not too expensive. There’s a few things you need to keep an eye out for when making a purchase though. As always read the product descriptions fully and take particular note of whether they suit the front or rear of the car. Wheel bearing kits are not usually handed so you don’t need to worry about left or right. When purchasing using your cars reg number you do still need to check out the details carefully as more than one product can still be listed for your car. Volkswagen Audi group cars in particular can be tricky as they often have variations listed based on PR codes – (you can usually find your build sticker containing your cars PR codes in the boot, near the spare wheel)
Another thing to bear in mind is that if you have the option of a wheel bearing kit or complete hub assembly it may end up being a false economy to go for the cheaper of the 2 options because a lot more labor would be required to fit the wheel bearing kit than it would the complete hub, so try and get a price from your mechanic on both jobs and work out which will be best for you in the long run
Replacing your wheel bearings.
Replacing wheel bearings is a job that can be done at home by competent DIYers with the right tools but in most cases it’s a job best left to the pro’s. You’ll often find that hub nuts will be seized solid and even the longest breaker bar won’t release them. Air impact guns are the best tool for the job here. In addition, removing and replacing the bearing itself from the hub may only be possible with a strong press. Even at that, it may be that the whole assembly requires additional heating with a gas torch if it has seized up completely. This really is a job for those with experience.
If the whole hub is to be replaced then it’s a different story, as fewer specialised tools are required and it becomes a more simple DIY task
Don’t panic if you think your car is developing a wheel bearing noise. They’re constructed of very strong steel and are highly durable. Even if they start making that characteristic whirring sound they’ll likely last a long time before ever failing completely. Saying all that, a terminal failure could result in a wheel locking up at speed, which would be highly dangerous and a bearing that is on the way out may overheat too, sending unwanted heat into the hub and brakes. So, panic not, but likewise, don’t leave it for months before getting it sorted!