Should sealed wheel bearing hubs be replaced individually or in pairs?
If one wheel bearing has reached the end of the road, chances are the
wheel bearing on the other side of the vehicle may also be nearing the
end of its service life, too. Both wheel bearings have racked up the
same number of miles, so it’s logical to conclude that both sides have
probably experienced the same amount of wear.
Based on this line
of thinking, it would make sense to recommend replacing both wheel
bearing hubs at the same time even though only one has obviously
failed. On the other hand, some would argue replacing both at the same
time would be an unnecessary expense. As long as the other wheel
bearing is not making noise and play is still within specifications, it
should remain in service. But the question is, for how long?
bearings are engineered to go a lot of miles, and often last the life
of the vehicle without ever being replaced (which may be upwards of
250,000 miles or more). However, their service life can sometimes be
cut short by driving conditions and environmental factors.
time a wheel hits a bump or pothole, the wheel bearings take a
pounding. The tire and suspension will cushion much of the impact, but
it still adds up over time. A vehicle that spends much of its life
driving on rough roads or cratered urban streets may wear out its wheel
bearings in as little as 100,000 miles. Taxis, police cars and delivery
vehicles can also wear out their wheel bearings rather quickly
depending on how they are driven. Hard cornering puts a lot of side
load on the bearings which they do not experience with normal driving.
This can also accelerate wear and lead to premature bearing failure.
Sealed wheel bearing assemblies are engineered to keep out
contaminants. Even so, over time seals can wear and lose their
elasticity, allowing road salt, moisture and dust to enter the bearing
housing. Once inside, these contaminants can cause corrosion and wear,
resulting in premature bearing failure. Driving though standing water
that is more than hub deep is another no-no that should be avoided
because it can force water into the bearings.
Though sealed wheel
bearings require no maintenance, there’s also no way to clean or
regrease the assembly if it has become contaminated. Replacement is
the only repair option.
Q. When should a wheel bearing be replaced?
The first sign of wheel bearing trouble is often noise (but not
always). A bad wheel bearing may make a rumbling, growling or chirping
noise that changes with vehicle speed. The noise should be investigated
without delay because a wheel bearing failure can sometimes allow the
wheel to separate from the vehicle!
The noise produced by a bad
wheel bearing will usually be proportional to vehicle speed, and will
not change in pitch or intensity when accelerating, coasting or
decelerating (which is often the case with noise produced by worn
differential, transmission or transaxle gears, or a bad U-joint). The
noise may change when turning, or become louder or even disappear at
certain speeds. But it shouldn’t be confused with the popping or
clicking sounds produced by a bad outer CV joint on a FWD car. A bad
outer CV joint usually only makes noise when turning, not when driving
straight ahead. As a rule, sealed wheel bearings and hubs should have
no play or roughness when a wheel is spun by hand. If a wheel bearing
feels loose, or has play that exceeds specifications when measured with
a dial indicator placed against the hub, it is worn out and needs to be
replaced without delay.