Distributors should watch out for 'knockoff' brands.
Today's hub bearing units have evolved to include sophisticated electronics, and the part itself is a vital item that cannot be second-guessed. And distributors should be aware that selling an off-brand or knockoff bearing unit could result in irritated customers.
Knockoff hub units will not last nearly as long as an OEM-approved part, says Don McEntee, VP of marketing for SKF.
"Hubs are a fairly technical part, and knocking them off in a best-cost country is not a very easy thing to do," he says. "They might look OK on the outside, but the life expectancy is significantly lower, and some have safety-related risk."
He adds that value-grade hubs may only last 20 percent or 30 percent as long as the OE equivalent.
The typical domestic hub bearing is intended to last 100,000 miles, but McEntee says none usually last that long. Some, he continues, may not even hold up through a vehicle's warranty period.
And shops can expect to see more hub replacement on domestic vehicles than foreign marques, he says, adding that typically foreign hub applications have longer lifecycles.
A hub bearing performs many jobs, enabling wheel rotation while supporting a vehicle's weight, and a bearing must be kept in a controlled environment, with grease seals that need protected from the outside elements. Exposure to a little rust or water can ruin this part.
Wheel hub bearings also are basically a recession-proof automotive part. According to market research firm The Freedonia Group, demand for tapered bearings is expected to climb more than 5 percent to $2.6 billion in 2011. Said to be the most common of bearings on the front wheels of rear-wheel drive vehicles, tapered roller bearings have what are referred to as a "cone" and a "cup."
In addition, a number of suppliers have chosen to sell higher-priced assemblies that incorporate bearings and additional parts like sensors in favor of tapered roller bearings.
One example, according to a Freedonia study, is Timken's pre-assembled RACEPAC, which includes pre-lubricated tapered bearings with ground spacers, a hub, seal and grease containment dam.
In some instances, Freedonia adds, ball bearings have replaced tapered bearings in hub units due to high cost. And "commodity-type" bearing products continue to make inroads into the U.S. marketplace.
Today's bearings incorporate such technology as ABS sensors, as well as sensors that detect and monitor vehicle speed and temperature, among other functions.
Hubs cannot be sold as a preventive maintenance item; however, it's probably a good idea to recommend that technicians look for signs of leaking grease when doing a brake job.
"You can physically inspect it to make sure it's not leaking any fluids," McEntee recommends.
A road test can determine a bad hub unit as well. If the driver hears a grinding or whining noise, it's an obvious sign of a bad bearing. And just because a noise emanates from the left side does not mean that the left hub bearing is faulty. It could be the other side overcompensating for a faulty bearing unit.
Ultimately, the best way to diagnose a hub, adds McEntee, is lifting the vehicle and listening through a stethoscope due to the component's sealed nature.
Another common question is: Should the bearing on the opposite side be replaced when changing a hub bearing? Not necessarily, adds McEntee. "Each hub stands on its own."
Here are some bearing replacement tips to pass along to your tech customers, courtesy of SKF:
- Always work with clean tools.
- Always use the proper grease and lubricant.
- Check the contact surface for the seal lip. The slightest marks or rust will damage the seal lip and allow corrosion.
- Never directly hit a bearing with a hammer.
- Always check the condition of the housing and axle when changing wheel bearings. The smallest wear can create misalignment.
- Never take a hub unit apart before mounting.
- Try not to move or adjust a seal on a hub unit.