Replacing wheel bearings on driven wheels
A front-wheel-drive system with the inner and outer wheel bearings inside a hollow hub carrier. They are separated by a short tubular spacer. The drive shaft runs through them into a splined drive flange, to which the wheels are bolted.
Cars with front-wheel drive have front-wheel bearings that resemble closely those in the rear wheels of rear-wheel-drive cars which have independent suspension (See How car suspension works).
The type of bearing used also has much in common with non-driven wheel bearings (See Checking the half shafts). However the bearings of live rear axles are quite different.
The main difference between driven and non-driven hubs is that a drive shaft projects into a driven hub from the inner side.
With non-driven bearings the hub turns outside a central, stationary, solid stub axle.
In some driven hubs the arrangement is similar, except that the `stationary axle’ – the hub carrier is hollow and the drive shaft runs through it to connect with the hub.
The hub bearings are exactly like those of a non-driven hub, and you dismantle them in the same order. But it is usual for the ‘hub’ – properly called the drive flange – to turn on bearings inside the hub carrier. So the inner race revolves, while the outer race is stationary.
There is likely to be a plastic water shield on the inner side of the hub assembly, either attached to the drive shaft or clipped to the hub carrier.
There is also an extra grease seal on the outboard side of the pair of bearings. As usual, renew all grease seals whenever you dismantle a hub. There may be additional spacer rings between the seals and bearing races.
Details vary from car to car: when dismantling, make notes or drawings of how all these parts are arranged and which way round they go.
Dismantling a driven hub
Dismantling is much the same as for a non-driven hub (See Removing wheel bearings). But there is one major difference — the hub nut is usually very tight; if possible, loosen it with the wheel on the ground.
Remove the hub dust cover and hub-nut locking device in the usual way — on some cars this means raising and removing the wheel, then replacing and lowering it.