Cars are the greatest. They get you to where you need to go… most of the time. They can also let you down at the worst moment if a critical part fails. Wheel bearings get a lot of use while we drive and [Dmitriy] found out the hard way how quickly they can fail. Instead of getting cranky about it, he set out to change the damaged bearing himself. In the process he made a pretty neat DIY bearing puller.
Some wheel bearings, on the front of a 2WD truck for example, are only held on by one large nut and easily slide off the spindle. This was not the case for the rear of [Dmitriy’s] AWD Subaru. The rear bearings are press-fit into a bearing housing. These are hard to remove because Outer Diameter of the bearing is actually just slightly larger than the Inner Diameter of the bearing housing. This method of retaining parts together is called an ‘interference fit‘.
[Dmitriy’s] gadget uses one of Hackaday’s favorite simple machines, the screw, to slowly force the bearing out of its housing. It works by inserting a threaded rod through the bearing and bearing housing. Each side has a large washer and nut installed as well as a PVC pipe spacer providing support for the threaded rod. As the opposing nuts are tightened, one washer presses against the bearing and the bearing slowly slides out of the housing. Installation of the new bearing is the same except the tool is reversed to press the bushing into the housing.
When pressing bearings into tight housings it is important to only press on the outer race. Conversely, when pressing a bearing onto a shaft it is important to press only on the inner race. That way the axial load being applied does not transfer through the bearing balls or rollers. This can indeed damage the bearing which would lead to premature failure. [Dmitriy] handled this by using appropriately sized washers that contacted the bearing’s outer race during removal and installation.
The graphics below shows the right and wrong way to install a bearing into a bearing housing. In the left graphic, pressing on the inner race will ‘squeeze’ the balls because the inner race wants to go in and the outer race wants to stay in place because there is resistance between the outer race and the bearing housing due to the interference fit. In the right graphic, pressing on the outer race does not put any load or stress on the balls and will result in a properly installed, damage-free bearing.