By Jim Kerr
The summer travel season has just started, with the May long weekend a time when many people take their first trip to the lake or camping. From what I saw on the road this past weekend, it was also about to be the first time for several travellers to become familiar with a repair shop. The biggest problem I saw on the road was wheel bearing failure.
Wheel bearing service used to be a common maintenance procedure on vehicles a few decades ago. Then along came front-wheel drive vehicles and with them, sealed wheel bearings. Many vehicles today use sealed wheel bearings, and either the bearing unit or the complete hub is changed when a bearing goes bad. However, there are still vehicles on the road that need wheel bearings serviced. Most of these would be rear-wheel drive trucks, and some four-wheel drive trucks, but a few passenger cars fall into that category as well. If you are in doubt as to whether your vehicle has serviceable wheel bearings, you can ask at a repair shop or check under the maintenance schedule in your owner’s manual.
Most of the wheel bearing problems I saw on the road were not on vehicles, but on trailers – house trailers, tent trailers and boat trailers. Servicing these bearings is the same as servicing the bearings on a vehicle, but they usually need to be done more frequently. Large trailers can place higher loads on wheel bearings. Small trailers often have small diameter tires that spin faster and place more load on the bearings. Boat trailers are the ones that need servicing at least annually, as water can get into the bearings when the trailer is backed into the water to load or unload the boat.
Servicing wheel bearings isn’t a difficult job and can be done in a driveway with few special tools. First you need to be able to jack the trailer or vehicle so the tire can be removed. Then you need to be able to block it safely so the trailer won’t fall. Wooden timbers will work. So will a safety stand, but it must be on a solid surface. Asphalt will allow the stand to dig in, so it must be on heavy plywood or better yet a concrete surface.
With the trailer blocked, the tin cap is removed off the axle hub. They make special pliers to do this but a small chisel and hammer will work. A few taps – don’t hit too hard – is all that is necessary. Under the cap, there is a bent cotter key that needs to be straightened and removed. Always replace this cotter key with a new one and bend it back the same way as it was before you removed it. Then there is a large nut that can be removed, and the hub and brake drum can slide off. On vehicles with disc brakes, the brake caliper and mount must be removed first, but you don’t need to disconnect the brake hose.
With the hub off, the bearing seal on the back side can be pried out with a large screw driver and the inner bearing slips out. The outer bearing will usually fall out when the hub is removed. Wash the hub cavity and bearings clean in solvent and let them air dry. Then inspect the bearings for roughness as you turn them, grooves or lines and metal chips or flaws. If you find any defects, replace the bearing and the inner race. The inner race can be removed from the hub with a punch and hammer but a punch can damage the new one during installation, so this might be a job to take to the local garage.
Pack the good bearings with wheel bearing grease. The easiest way to do this is to place a blob of grease in one palm about the size of a Tooney and work it into the wheel bearing rollers by scraping the bearing against your hand. It is a little messy but only takes a couple minutes. Coat the inside of the hub with a light layer of grease, tap in a new wheel bearing seal and you are ready to install the hub again.
Install the hub in reverse order of disassembly, but you do have to adjust the bearing too. Tighten the large nut to about 12 foot pounds (snug but not tight) as you spin the hub. Then back off the nut, tighten it by hand only and then install the new cotter key. If you have to back the nut off to install the cotter key, back it off no more than one flat on the nut. When the bearing is adjusted properly, the hub should turn freely with no in or out play or movement. Coat the tin cap with a little grease on the edge to help keep out water and tap it in place. Finish up with the wheel and blocks and you are ready to go.
Bearings don’t fail often, but when they do they can cause a lot of other damage. They can also ruin a holiday, so a little preventive maintenance can make travel a lot more fun.