1. The new bearings might be of lower quality then the old ones. Are the new ones made in china?
2. Many new bearings need to be packed with grease. It is very important that the grease you pack in is clean, no dirt!
3. Many cars use sealed bearings that must be pressed in place. A hammer will not do, will only mess them up. It is also critical that the bearing is pressed in by applying force only to parts that do not load the ball bearings.
4. Some cars with sealed bearings MUST have the big nut/bolt torqued high enough. If the torque is not high enough the bearings wear out very quickly.
2. Many new bearings need to be packed with grease. It is very important that the grease you pack in is clean, no dirt!
3. Many cars use sealed bearings that must be pressed in place. A hammer will not do, will only mess them up. It is also critical that the bearing is pressed in by applying force only to parts that do not load the ball bearings.
4. Some cars with sealed bearings MUST have the big nut/bolt torqued high enough. If the torque is not high enough the bearings wear out very quickly.