Fit seals and bearings the right way round without damage

A ball bearing is delicate. Balls sit in a thin steel cage between two rings. A blow through the balls bends the cage and ruins the bearing. Seals fail if fitted backwards or dry.

Safety

• Wear eye protection. Hot parts burn.
• Use a driver that fits the race. Never hammer directly on a bearing or seal.

Bearings

1. A bearing you will reuse must not be driven out through the balls. Support and push on the ring that is in the tight fit.
2. A bearing going in a housing: push on the outer race. A bearing going on a shaft: push on the inner race.
3. Fit the bearing with the maker's name and size numbers facing out, so you can read them from the side you fit it from.
4. Heat the housing with a hot air gun and chill the bearing in the freezer. This helps it drop in: Use heat and cold.
5. A bearing you are replacing anyway can be driven out any way. Use the correct driver on the new one.

Seals

1. Fit seals with the lettering and markings facing out, away from what they seal.
2. Pack the space between the lips with grease.
3. Drive the seal in square, using a driver that sits on its outer edge. See Fit an oil seal.

Circlips

• Circlips have a rounded edge and a sharp edge from the way they are made. Fit them with the sharp edge facing away from the push of the load.

Check your work

• The bearing spins smoothly and quietly by hand and has no side play.
• The seal is flush and has no wrinkles.

If it did not fix the problem

• Bearing noise: Rumbling or growling from inside the engine.
• Wheel bearing: Replace a wheel bearing.