mechanic says my suspension is not adjustable. Does that mean
the wheels can't be aligned?
What causes a vibration when I'm driving at highway
How do I know if my vehicle really needs new shock
Do my wheels need to be realigned after the struts
have been replaced?
My mechanic says my car needs ball joints. Please
My front-wheel drive car makes a clicking sound
when turning. Is anything wrong?
What's the difference between a U-joint and a constant
velocity (CV) joint?
Why do front-wheel drive cars and minivans have
CV joints instead of ordinary U-joints?
Why are CV joints so expensive to replace?
My mechanic tells me my front-wheel drive (FWD)
car has a bad outer CV joint. He says the shaft has to be replaced.
Isn't there a less expensive way to fix it?
How do I check the Shock Absorbers?
How do I Remove and Replace Shock Absorbers?
Clunking from under the car when gears change.
Clicking from the front while turning a corner.
What is this?
Hard gear changes. Why?
Wheel shimmy exists. Why?
Car seems to bounce too much. Why?
Clicking noise during braking or turning. What's
Tires wobble while driving. Why?
Tires are wearing more on one edge than the other.
mechanic says my suspension is not adjustable. Does that mean
the wheels can't be aligned?
No, it simply means the vehicle manufacturer
was too cheap to design adjustable suspension components when
it engineered your car. When a car maker designs a car, engineers
and accountants scrutinize each and every component to figure
out how they can reduce manufacturing and assembly costs. If
a few cents can be saved by leaving out an adjustable camber
bolt, caster shim or whatever, they'll do it. They may have
great faith in their own ability to build a vehicle that never
needs to be aligned or fixed, but we all know from experience
that such notions are untrue. So even though a suspension is
nonadjustable and shouldn't require any corrections, that doesn't
necessarily make it so. Even brand new vehicles can roll off
the assembly line with wheels that don't meet their own alignment
the aftermarket has come up with ways to correct the "mistakes"
of the vehicle manufacturers. If the car maker doesn't include
provisions for adjusting the suspension, it creates an opportunity
for some aftermarket part's supplier to come up with means of
making such adjustments possible. These include offset bushings,
shims, wedges and other alignment aids. So even though your
suspension may have few if any adjustments for things like camber,
caster and rear toe (front toe is adjustable on all cars and
trucks), there are probably aftermarket alignment aids that
allow at least some limited corrections to be made on nonadjustable
causes a vibration when I'm driving at highway speeds?
The most likely cause is an out-of-balance wheel and tire. But
vibrations can also be caused by a tire or wheel that's out
of round (excessive runout), "heel-and-toe" wear on
a tire, driveshaft imbalance, or even harmonic vibrations in
the engine and drivetrain.
balance: For a wheel to roll smoothly, it must be properly balanced.
Balancing the wheel and tire involves spinning at high speed
to determine where the "heavy" spots are. Small lead
weights are then positioned opposite the heavy spot to counteract
the forces generated when the wheel spins. If your wheels have
never been balanced, if you've lost a wheel weight, or if you've
put a lot of miles on your tires since they were last balanced,
wheel imbalance may be causing your vibration problem. The way
to find out is to have the wheels rebalanced. If the vibration
goes away, you've cured the problem. If the vibration remains,
then it's something else. Wheel balance problems can usually
be felt in the steering wheel, and grow in intensity the faster
you drive. Below 45 mph, you usually don't feel a thing. But
by 55 or 60 mph, you feel a steady shake. Most wheels today
are balanced using an off-car electronic spin balancers. These
machines are extremely accurate and usually do an excellent
job of balancing wheels and tires. But because the wheels are
balanced off the vehicle, the machine does not take into account
any imbalance in the brake rotors or drums. Consequently, you
may still have a balance problem even though the wheels have
been properly balanced. The cure here is to have the wheels
balanced using an "on-car" wheel balancer. Though
on-car balancers are hard to find today, and are difficult to
use on front-wheel drive and four-wheel drive vehicles, an on-car
balancer will compensate for rotor or drum imbalance.
runout: If wheel balance isn't the problem, the next thing to
check would be wheel and tire runout. This usually requires
positioning a dial indicator against the center of the tire
tread and noting how much runout occurs as the tire is rotated
by hand. More than about .050 inch of runout can cause vibration
problems. If you don't have a dial indicator, hold a pencil
or stick on a block of wood near the center of the tread and
observe how much the tread moves in and out as the tire is rotated.
If runout is more than the thickness of a nickel, it may be
your problem. Runout can be corrected several ways. One is to
remove the wheel and remount it on the hub in a different index
position (lined up so the lugs go through different holes than
before). This may help to reduce runout caused by an off-center
hub or a wheel that wasn't manufactured with perfectly centered
holes. Another way to correct runout is to dismount the tire
from the wheel. A dial indicator can then be used to find the
high and low spots on both the tire and wheel. The tire is then
remounted on the wheel so the tire high spot lines up with the
wheel low spot. This may reduce overall runout to the point
where vibration is no longer a problem. If that doesn't work,
a "tire truing" machine (if you can find a service
facility that has one) can be used to shave rubber off the tire
and make it round again. This will reduce the life of the tread
somewhat but it's cheaper than replacing the tire and/or wheel,
which is the last resort to solving a runout problem.
& toe wear: Some low profile performance tires have a tendency
to develop an unusual heel-and-toe wear pattern on the tread.
When you look closely at the blocks of rubber, the forward or
trailing edges of the blocks will be worn unevenly so the forward
edge of one block will be higher or lower than the block that
follows it. This rough wear pattern causes a vibration that
is most noticeable at speeds above 40 mph. It also produces
noise. The wear pattern develops because of the way the tire
is built, and the only way to prevent it is to rotate the tires
frequently (every 8,000 miles or so). If your tires have this
kind of wear pattern, it may be too late to counteract the condition
by rotating the tires. Replacing them may be the only way to
get rid of the vibration.
imbalance: Vibrations caused by driveshaft imbalance are not
very common, especially on front-wheel drive cars and minivans.
But it may occur on a rear-wheel drive car or truck if a balance
weight falls off the driveshaft. Driveshaft vibrations can also
be caused by worn U-joints or a worn or loose center carrier
bearing on a two-piece driveshaft. If you've raised the suspension
on a truck or sport utility vehicle, it's also possible to create
vibrations due to the altered driveshaft angle. U-Joints will
produce cyclic vibrations if operated at more than a few degrees
vibrations: Vibrations can also be caused by the engine or engine-mounted
accessories. A noisy air conditioning compressor, power steering
pump, air pump, an out-of-balance engine-driven fan, etc., can
all create annoying vibrations. If the vibration seems to vary
more with engine speed than vehicle speed, suspect this kind
of problem. Check for loose mounting brackets, bolts, fasteners,
or physical contact between the accessory and some other component.
Many engines also have certain rpm ranges at which they tend
to produce more noise and vibration than others. Many newer
engines have counterrotating "balance shafts" to help
dampen these vibrations. A sudden change in the vibration characteristics
of your engine, therefore, may indicate a collapsed or broken
motor mount, or a failure of the balance shaft drive gears or
do I know if my vehicle really needs new shock absorbers?
You need new shocks (and/or struts) if your
original shocks (or struts) are worn out, damaged or leaking.
Leaking is easy enough to see (just look for oil or wetness
on the outside of the shock or strut) as is damage (broken mount,
badly dented housing, etc.). But wear is often more of a subjective
thing to judge. There are also instances where the original
equipment shocks may not be worn, damaged or leaking, but may
not be adequate for the job they're being asked to do. In such
cases, upgrading the suspension with stronger, stiffer or some
type of special shock (or strut) may be recommended to improve
handling, for trailer towing, hauling overloads or other special
and struts do not require replacing at specific mileage intervals
like filters or spark plugs, but they do wear out and eventually
have to be replaced. How long a set of original equipment shocks
will last is anybody's guess. Some original equipment shocks
may be getting weak after only 30,000 or 40,000 miles. Struts
usually last upwards of 50,000 or 60,000 miles. But when exactly
a shock or strut needs to be replaced is hard to say. Because
the damping characteristics of shocks and struts deteriorate
gradually over time, the decline in ride control often passes
unnoticed. So by the time to think you need new shocks or struts,
it's usually way past the point when they should have been replaced.
way to evaluate your need for new shocks or struts is to consider
how your vehicle has been handling and riding lately. Does it
bounce excessively when driving on rough roads or after hitting
a bump? Does the nose dip when braking? Does the body roll or
sway excessively when cornering or driving in crosswinds? Does
the suspension bottom out when backing out of the driveway or
when hauling extra passengers or weight? A "bounce test" is still a valid means of checking the dampening ability of
shocks and struts. If the suspension continues to gyrate more
than one or two times after rocking and releasing the bumper
or body, your shocks or struts are showing their age and need
to be replaced.
replace them? Weak shocks and struts won't necessarily create
a driving hazards if you continue to drive on them, but there
are studies that show worn shocks increase the distance it takes
to stop a vehicle on a rough surface. Increased body sway due
to weak shocks or struts can also increase the risk of skidding
on wet or slick surfaces.
shocks and struts also increase suspension wear (though marginally)
but can have an effect on tire wear. If the shocks are really
bad, the tires can develop a cupped wear pattern. The reason
why most people decide to have worn shocks or struts replaced,
however, is to improve overall ride quality. If you're sick
of bouncing and rocking on rough roads, a new set of shocks
or struts will firm up your suspension and restore proper ride
control. If you're interested in performance handling, you can
upgrade to premium "gas" charged shocks or struts.
These are charged with high pressure nitrogen gas to help minimize
foaming in the hydraulic fluid inside the shock. This lessens
"fade" on rough roads and helps the vehicle maintain
better ride control when cornering. There are also "heavy-duty"
replacement shocks and struts that have larger diameter pistons
than stock. These too, provide increases resistance for greater
control -- but may be a little too harsh for everyday driving.
So some shocks have special valving or adjustable valving that
allows the amount of resistance to vary. Another option to consider
if you tow a trailer or haul extra cargo are overload or air-assist
shocks. Overload shocks have a coil spring around them to increase
the load carrying capacity of the suspension (these also tend
to ride stiffer than standard replacement shocks). Air-assist
shocks have an adjustable air bladder that acts like a spring
to carry extra weight. With this type of shock, air can be added
on an "as needed" basis when hauling extra weight.
Shocks and struts are generally replaced in pairs -- though
this isn't absolutely necessary if only one shock or strut is
leaking or has suffered damage at a low mileage. Shocks are
a popular do-it-yourself item on most vehicles because they're
fairly easy to replace. But struts are not. Most struts require
a fair amount of suspension disassembly as well as a spring
compressor. What's more, the wheels must usually be realigned
after replacing a strut. For this reason, you're probably better
off letting a professional replace your struts.
| Do my wheels need to be realigned after the struts have been replaced?
On most vehicles they do. Here's why: MacPherson struts are
more than overgrown shock absorbers. They're an integral part
of your vehicle's suspension. They replace the upper control
arms and ball joints and serve as the steering pivots for the
front wheels. When the strut assembly is unbolted and removed
from the vehicle, the original alignment of the suspension is
lost -- unless the position of the camber bolts and upper strut
plate are first marked so they can be reinstalled in exactly
the same position as before. But this only works if the same
original strut is being put back into the car. If the strut
is being replaced because it is leaking, damaged or worn out,
the dimensions of the new strut will usually vary enough to
cause a change in wheel alignment. So wheel alignment should
at least be checked to see if adjustment is necessary (which
it usually is). On some import cars, the struts are "rebuildable."
The housing has a removable nut that allows the old guts inside
to be dumped out and a new cartridge installed. On these vehicles,
it should not be necessary to realign the wheels after rebuilding
mechanic says my car needs ball joints. Please explain. ?
Ball joints are a part of your vehicle's suspension that connects
the steering knuckles to the control arms. A ball joint is essentially
a flexible ball and socket that allows the suspension to move
and at the same time the wheels to steer. Cars and trucks without
strut suspensions typically have four of them (one upper and
one lower on each side). Cars and minivans with strut suspensions
have only two (one lower ball joint on each side). Some front-wheel
drive cars also have ball joints on the rear suspension. Like
any other suspension component, ball joints eventually wear
and become loose. Excessive play in the joint can affect wheel
alignment and tire wear. Loose joints can also cause suspension
noise (typically a "clunking" sound when hitting a
bump). Warning: If a ball joint fails, the suspension can collapse
causing a loss of control. So don't put off having a bad set
of joints replaced.
inspection: Joints should be inspected before they're greased
(since grease takes up some of the slack in the joint). Ball
joints are pretty easy to check, but each type requires a different
inspection procedure. Use the wrong procedure and you'll get
misleading results. The procedure that needs to be used depends
on the location and loading of the joint:
load carrying ball joints are found on front- and rear-wheel
drive vehicles where the coil spring or torsion bar is on the
lower control arm. Joints with built-in wear indicators must
be checked with the full weight of the vehicle on the tires
on the shop floor or on a drive-on style ramp -- not with the
wheels up or the suspension supported by jack stands. No measurements
are required if a joint has a wear indicator because internal
play is indicated by the position of the grease fitting boss.
The boss protrudes about .050 inches on a new joint. As the
joint wears, the boss recedes into the housing. The joint is
considered "good" as long as you can see or feel the
edge of the boss protruding from the housing. But if the top
of the boss is flush or below the housing, it's time to replace
lower load carrying ball joints without a wear indicator, the
joint is checked in the unloaded condition with the wheel raised
off the ground and the lower control arm supported by a jack
stand. A dial indicator is then used to measure play in one
of two directions: sideways (horizontal or radial play) or vertically
(axial or up-and-down play). The direction to measure depends
on the application (refer to a manual for the exact specs).
Sideways play is measured with the indicator positioned against
the inside of the wheel rim near the joint. The wheel should
be pushed in and out by hand to check sideways play, and lifted
with no more than 25 lbs. of force to check vertical play. Many
joints allow up to .250 in. of sideways (radial) play, but some
allow no play or only .015 in. of play. Always refer to the
vehicle manufacturer's specs. Vertical play is measured with
the dial indicator positioned against the knuckle stud nut or
the joint housing. A joint that has more than .050 in. of vertical
play doesn't necessary require replacement because the specs
range from zero play to as much as .125 inch of play. The most
common mistake that's made here is to use too much pressure
on a pry bar or to insert a pry bar between the control arm
and knuckle rather than under the wheel. Pry hard enough and
any joint may appear to be bad.
follower nonloaded ball joints are found on two kinds of applications:
RWD cars where the spring is over the upper control arm, and
vehicles with MacPherson strut suspensions. On both applications
the lower joint is checked with the wheel raised off the ground
hanging free (no stand under the lower control arm). Rock the
wheel in and out by hand. A good joint should show no movement.
load carrying ball joints are found on vehicles where the spring
or torsion bar is on the upper control arm. Like the lower follower
nonloaded ball joints, the upper joints are checked in the unloaded
condition with the wheels off the ground -- but with a wedge
or block between the frame and upper control arm to support
the upper arm. On most applications, any movement calls for
replacement. But on some Fords, up to .250 in. of radial play
follower nonleaded ball joints are also checked with the wheels
off the ground but with the lower control arm supported. Any
movement usually calls for replacement.
replacement: Any joint that exceeds the vehicle manufacturer's
maximum allowable wear needs to be replaced. The greater the
amount of wear, the greater the urgency to replace it. Ball
joints are often replaced in complete sets, or at least in matched
pairs on both sides (both lowers or both uppers). This is because
the joints on both sides of a vehicle usually have the same
amount of wear. If one is bad, the other usually is too. Load
carrying ball joints usually wear out before ones that don't
carry a load, so it may only be necessary to replace the loaded
joints instead of the complete set. Replacing a set of ball
joints requires separating the control arms from the steering
knuckles, a job which can be difficult depending on the design
and age of the vehicle. At the very least, it usually requires
a special "ball joint fork" tool to loosen the ball
joint stud from the knuckle. If this sounds like more of a job
than you want to tackle, let a professional do it the work.
front-wheel drive car makes a clicking sound when turning. Is
Yes. A clicking sound when turning is one of
the classic symptoms of a worn or damaged "constant velocity"
(CV) joint. Your car has four such joints on the two front axles:
two inboard joints and two outboard joints. The outboard joints
are the ones that make a clicking sound when they go bad. Inside
the joint are six steel balls, positioned in grooves between
an inner race and an outer housing. The balls are held in position
by a cage that looks something like a wide bracelet with windows
or slots cut in it. When the joint is new, the balls fit tightly
into the cage windows. But as the joint accumulates miles, the
cage windows become worn and allow the balls to rattle around.
The grooves in the inner race and outer housing also wear, which
further contributes to noise. When driving straight, a worn
CV joint is usually quiet (constant noise would indicate a bad
wheel bearing or other problem). But when the wheels are turned
to either side, the joint bends causing the balls to click as
they slide around in their cage windows and grooves. The noise
is usually loudest when backing up with the wheels turned. Repacking
the joint with grease won't help because the joint is worn and
needs to be replaced. The "normal" life of a CV joint
is usually 100,000 miles or more. But a joint can fail prematurely
if the rubber boot that surrounds it is damaged or develops
Joint Boots: The boot, which is made of rubber or hard plastic,
serves two purposes: it keeps the joint's vital supply of special
grease inside, and it keeps dirt and water out. After five or
six years of service, it's not unusual for the boot to develop
age cracks or splits. Boots can also be damaged by road hazards
or a careless tow truck operator who uses J-hooks to tow your
vehicle. Once the boot seal is broken, the inside grease quickly
leaks out. Starved for lubrication, the CV joint soon fails.
Dirt and water can also enter the boot and contaminate any grease
that's left inside. Either way, a damaged boot is bad news for
the joint. CV joint boots should be inspected periodically (when
the oil is changed is a good time) to make sure they are not
cracked or torn, and that the clamps are tight. If you see grease
on the outside of the boot, it is leaking and needs to be replaced
(the sooner the better). If a clamp is loose and the boot is
leaking grease at one end, the clamp needs to be replaced.
equipment boots are a one-piece design, which means the driveshaft
and CV joint have to be removed from the vehicle and disassembled
to replace a bad boot. However, there are aftermarket "split-boots"
designed for easy do-it-yourself installation. The split-boots
eliminate the need to remove and disassemble the joint and driveshaft.
You simply cut off the old boot, clean out as much of the old
grease as possible from the joint, pack the joint with fresh
high temperature CV joint grease (never ordinary chassis grease),
then install the new boot. Most split-boots have a seam that
is glued together. The seam must not have any grease smeared
on it and the glue must be applied carefully for a good seal.
Also, the vehicle must not be driven until the glue has cured
(about an hour or so). Note: Most professional mechanics do
not use split-boots because (1) they don't think a split-boot
is as reliable or as long-lived as a one-piece original equipment
style boot, and (2) they don't like the idea of installing a
new boot on a questionable joint.
the time a damaged or leaky boot is noticed, the joint has usually
lost most of its grease and/or been contaminated by dirt. Unless
the joint is removed, disassembled, cleaned and inspected, there's
no way to know if it is still in good enough condition to remain
in service. If it's making noise, replacing the boot would be
a waste of time because the joint is bad and needs to be replaced
(most new joints come with a new boot, clamps and grease). But
even if the joint isn't making any noise, it may still have
wear or internal damage that will soon cause it to fail. Warning:
A CV joint failure can cause loss of steering control under
certain circumstances. If the joint locks up, it can prevent
the wheels from being turned.
the difference between a U-joint and a constant velocity (CV)
A U-joint (the "U" stands for "Universal"),
which is also called a "Cardan" joint after the guy
who invented it, is a type of flexible coupling typically used
on both ends of the driveshafts in rear-wheel and four-wheel
drive vehicles. Each U-joint consists of a four-legged center
cross with needle bearing cups on the ends of each leg of the
cross. The bearing cups on one pair of legs are mounted to the
driveshaft. The other pair of cups are held in place by a pair
of U-bolts attached to a yoke that mates to either the transmission
or differential. The bearing cups allow the joint to swivel
and bend as the driveshaft follows the motions of the differential
and axle as the suspension bounces up and down. Most original
equipment U-joints on newer vehicles are "sealed"
and do not require periodic greasing. But many replacement U-joints
as well as the U-joints on older vehicles do have a grease fitting
which allows the joint to be lubed periodically.
Joints: Aconstant velocity (CV) joint does essentially the same
thing as a U-joint, only better. There are two basic types:
"ball-and groove" CV joints (called "Rzeppa"
joints after the guy who invented them), and "tripod"
CV joints. Rzeppa CV joints, which are used as the outer joints
on most front-wheel drive cars and minivans, consist of a cup-shaped
outer housing, a center race and cage assembly. Machined into
the outer housing and center race are six grooves that hold
six steel balls. The balls are held in position by windows or
slots cut into the cage assembly. The joint is designed so that
when it bends, the balls are always positioned at the midway
point inside the joint. This eliminates the cyclic variations
in speed that a U-joint experiences when it operates at more
than a few degrees off-center.
variation on the Rzeppa CV joint is the "cross-groove"
CV joint. It also has six balls between an inner race and outer
housing. But this type of joint is designed to move or plunge
in and out to compensate for changes in driveshaft length that
occur as the suspension moves up and down. This type of joint
is used as the inboard CV joint on many European and Japanese
front-wheel drive cars.
tripod style of CV joint consists of a three-legged cross or
trunnion with roller bearings on the end of each leg. The trunnion
is attached to the driveshaft, and the roller bearings run in
machined grooves or channels in an outer "tulip" housing.
This type of joint is also designed to plunge in and out, and
is used as the inner CV joint on most domestic front-wheel drive
vehicles. There are also some Japanese and European front-wheel
drive cars that use a tripod-style joint as the outer joint.
All CV joints are enclosed by a rubber or hard plastic boot.
The boot keeps grease in and contaminants out. CV joints do
not require periodic maintenance or greasing, and are engineered
to last 100,000 miles or more.
front-wheel drive cars and minivans have four CV joints: one
inner joint and one outer joint on each of the vehicle's two
driveshafts (which are also called "halfshafts").
CV joints are also used on the driveshafts of some rear-wheel
and four-wheel drive vehicles, too.
do front-wheel drive cars and minivans have CV joints instead
of ordinary U-joints?
U-joints are not used with front-wheel drive (FWD) because they
produce cyclic vibrations when operated at more than a few degrees
off-center. A U-joint will cause a change in speed between the
driving and driven shafts whenever the joint operates at an
angle. As the operating angle of the joint increases, the speed
(velocity) of the driven shaft starts to vary during each revolution.
And the greater the operating angle, the greater the variation
in speed of the driven shaft. The driven shaft still turns at
the same number of revolutions per minute as the shaft that's
driving it, but because of the geometry of the U-joint the speed
of the driven shaft alternately increases (accelerates) and
decreases (decelerates) four times every revolution -- which
causes the vibrations we're talking about. This isn't a concern
in a rear-wheel drive application because the U-joints on the
ends of the driveshaft are positioned 180 degrees to one another
to cancel out vibrations. What's more, both U-joints always
operate at the same angle. But in a front-wheel drive application,
the outer joint may have to operate at an angle of up to 45
degrees when the wheels are steered. This is too much of a difference
between the inner and outer joints angles for U-joints to handle.
So constant velocity (CV) joints are required. Unlike a U-joint,
a CV joint always drives the output shaft at the same speed
as the input shaft regardless of the operating angle of the
joint. Therefore, it doesn't make any difference if the inner
and outer joints operate at different angles.
geometry: In a U-joint, the four-point center cross attaches
at two points on either yoke. When the joint is bent, two of
the arms on the center cross travel in one elliptical path while
the other two arms follow a different elliptical path. This
is what causes the speed variations that result in vibration.
It's hard to visualize, but that's what happens. CV joints handle
joint angularity differently. The six balls inside a "Rzeppa"
style CV joint are positioned so they always travel in a circular
path exactly half way between the joint angle. A circular path
keeps velocity constant while an elliptical path causes changes
in velocity. So that's the inside scoop on why U-joints won't
work in FWD applications.
are CV joints so expensive to replace?
There are two reasons why: parts and labor. A CV joint has a
lot of metal and precision-machined components so manufacturing
and tooling costs are high. Note: You can save some money by
going with a rebuilt joint, but it's still going to cost a substantial
sum and may not hold up as well as a brand new joint (durability
varies greatly depending on the rebuilding procedure used: some
joints are overhauled using oversized components to compensate
for wear while others are remachined to restore like-new tolerances).
Labor (unless you're replacing the joint yourself) is the other
factor that adds to the cost of replacement. CV joints are mounted
on the ends of the driveshafts located between the transaxle
and wheels in a front-wheel drive car. To replace a joint, the
driveshaft must be removed from the car. This, in turn, requires
removing the wheel, removing a large hub nut that holds the
outer end of the driveshaft in the wheel hub, disconnecting
the lower ball joint from the steering knuckle so the end of
the driveshaft can be pushed back through the hub, and disconnecting
the inner end of the driveshaft from the transaxle. With the
proper tools and a hoist, a skilled mechanic can usually remove
a shaft in an hour or less. But most shops charge according
to a "flat rate" system based on "average"
labor times published in a manual. These times are established
by the vehicle manufacturers and/or the flat rate manual publishers.
Most good mechanics can easily beat the flat rate times, and
earn themselves a commission on the difference. Unfortunately,
you still pay the same as if it took them the full amount of
time to complete the job. Hey, nobody said life was fair.
mechanic tells me my front-wheel drive (FWD) car has a bad outer
CV joint. He says the shaft has to be replaced. Isn't there
a less expensive way to fix it?
Time is money in the auto repair business. It's much faster
and easier for a mechanic to replace the entire driveshaft assembly
with both joints on it than to mess around replacing a CV joint
on your old driveshaft. Removing the old CV joint from the shaft,
disassembling and inspecting the other CV joint on the shaft
to make sure it is still good, reassembling and repacking both
joints with grease and installing the boots and clamps is a
messy and time-consuming job. So that's why your mechanic is
trying to give you the "shaft." He isn't trying to
cheat you. He's only trying to save himself some time and effort.
The cost of replacement shafts for most FWD cars today has dropped
to the point where a complete shaft assembly with new or remanufactured
CV joints costs little more (or in some cases no more!) than
a brand new replacement joint. That's why most mechanics have
gone to swapping shafts instead of replacing individual CV joints.
When the shaft is changed, your old shaft and joints are exchanged
for the replacement shaft. Your old shaft is then returned to
a company that specializes in shaft rebuilding. Your old shaft
is then rebuilt using new or remanufactured joints. The shaft
then goes back into the parts distribution pipeline and is sold
to the next person who needs one. That's how the system works.
It's recycling in action, and it actually saves consumers a
lot of money. If you're pinching pennies and/or don't plan to
keep your car for a long time, you can save some money by asking
for a shaft with remanufactured, rather than new, joints. The
warranty won't be as good, and the joints may not last as long
as brand new ones, but you get what you pay for. Shafts for
import vehicles typically cost about 30% more than those for
domestic vehicles because there are more different designs of
import shafts and joints (some of which can be very difficult
and expensive to obtain).
do I check the Shock Absorbers?
Whenever you inspect the suspension system, you should test
the shock absorbers or MacPherson struts. The test should be
performed with the car on the ground, not when the car is being
supported on a jack or hoist. The way to test the front and
rear shocks or MacPherson strut cartridges is by bouncing each
corner of the car. Rock the car at each corner and release.
If the car bounces more than 1 1/2 times after you have stopped,
take a closer look at the shocks or cartridges. If the car bounces
more than it should, raise the car up on a jack. Run your hand
over the tire tread completely around the tire and from inside
to outside. Cupping or unusual wear in any area indicates the
shocks may not be holding the tires on the road. Look for broken
mounts, damaged bushings, and oil on the shock absorber barrel.
Grab the shock and shake firmly. This may reveal damage to a
mount or bushing not apparent at first sight. Substantial fluid
on the outside of the shock absorber housing indicates a leaking
seal. Fluid cannot be replaced and shocks are ineffective without
fluid; shock absorber replacement is required. Shocks should
always be installed in pairs, and it is often most economical
to replace all four. One indicator of a need to replace the
MacPherson strut/shock is oil leakage at the piston rod seal.
Also conduct a bounce test. During the bounce test, carefully
observe the top strut mount. Any noise or movement here can
indicate the need for parts replacement.
do I Remove and Replace Shock Absorbers?
When replacing front or rear shocks, first compare the shocks
on the car to the replacement units. The old and new shocks
should be the same length and same mounting; carefully observe
the position and type of mounting of the original shock absorbers.
The shock absorber can be mounted by a thread formed on the
end of the piston shaft. This is called a stem mounting. Stem
mounting is common on the top end of a shock mounted in the
center of a coil spring. The tab stud or cross pin mount is
used on the bottom of many coil spring-mounted shock absorbers.
Sleeve mounting may be used on one or both ends of the shock
absorber; it is used on some front shocks, but is most common
on the rear. Before removing any shock absorber hardware, spray
penetrating fluid on all the threads. Road splash and rust can
make nuts very difficult to remove. Some nuts will probably
have to be removed with an air impact wrench and impact socket.
To remove front or rear shock absorbers, raise the car on a
hoist. Do not allow the front or rear drive axle to hang--make
sure it is supported on the hoist. To remove the typical stem
and cross pin-mounted front shock absorber, use an open-end
wrench to hold the shock absorber stem as shown below. Remove
the nut, then remove the upper washer and grommet. Unbolt the
cross pin from the lower control arm and pull the shock absorber
out through the bottom of the control arm. Make sure the correct
number and type of lower rubber grommets and washers are positioned
on the stem. Check the instructions with the new shocks and
also compare with the old shock mounting. Push the new shock
absorber into position through the hole in the bottom control
arm. Install the upper washer and grommet, then install the
nut. Use an open-end wrench to hold the stem and torque the
nut to specifications. Install the bolts that hold the cross
pin and torque them to specifications. Rear shocks are often
mounted with a stud or cross pin at one end and a sleeve mount
at the other end. The stud and cross pin are removed and replaced
by the procedure described earlier for front units. The sleeve
mount is removed and replaced by removing and replacing the
bolt and nut that goes through the sleeve into the mounting
bracket. Be sure to torque all the attaching bolts to specifications.
from under the car when gears change. What's up.?
When you shift gears (with an automatic or manual transmission),
you feel a slight pause, then hear a clunk. The can sound like
it is coming from the rear or front of the car. The noise may
be evident when shifting from reverse to neutral, neutral to
forward, or forward to reverse. The problem begins gradually
and worsens with use. The probable causes are: 1. Worn CV-joints.
2. Worn U-joints. 3. The differential unit may have too much
backlash. 4. The engine's idle speed may be set too high.
from the front while turning a corner. What is this?
Everything seems fine while you are driving your car except
when you go around a corner, and then you hear a clicking noise
from one side of the car. Pay attention to when the sound occurs,
as it is very helpful when trying to identify what is causing
the problem. Normally the problem begins gradually, but the
noise may go unnoticed. As the problem gets worse, the noise
gets louder. The probable causes are: 1. Loose brake pads. 2.
Worn wheel bearings. 3. Worn CV-joints (normally the outer joints).
4. Loose wheel covers, which are sometimes called hub caps.
5. There is a large stone, a nail, or some other hard object
caught in a tire.
gear changes. Why?
Whenever you place the transmission into gear when the engine
is warm, you notice a clunk or a jarring motion. Sometimes,
the change of gears while on the road feels very harsh and immediate.
Normally you hardly notice the transmission changing gears,
but now you do. The probable causes are: 1. The transmission
fluid level is low. 2. The fluid in your transmission is contaminated.
3. You have an internal problem in the transmission. 4. The
idle speed of your engine is too high. 5. You have worn CV-
or U-joints. 6. The throttle linkage for the transmission is
out of adjustment or damaged.
shimmy exists. Why?
You notice a side-to-side wobble in the steering wheel when
traveling at steady speeds. The vibration gets worse when you
are on an uneven road surface or after going over a pot hole.
The probable causes are: 1. Your tires and wheels are out of
balance. 2. Your tires don't have the correct pressure. 3. Your
tires are worn. 4. A part of the steering linkage is loose or
damaged and needs to be replaced. 5. You have worn suspension
seems to bounce too much. Why?
As you drive down the road and go over a bump, you feel the
car continue to bounce up and down well after the bump. Normally
this problem will get progressively worse as you continue to
drive your car.The probable causes are: 1. Your shock absorbers
are worn. 2. The mounts for your shock absorbers are broken.
3. Tyre pressure needs to be checked.
noise during braking or turning. What's up?
You notice a distinct click that increases in speed as you increase
the speed of the car. The clicking seems to occur whenever you
apply the brakes and/or make a turn. If the clicking disappears
when you release the brake, the cause is undoubtedly related
to the brakes. This problem gradually becomes noticeable and
can develop into a major problem. The probable causes are: 1.
Worn wheel bearings. 2. The brake pads are loose in their mounting.
3. CV-joints are worn. 4. There is a hard object caught between
the brake pads and the rotor.
wobble while driving. Why?
As you drive the car, you feel a shake through the steering
wheel from the tires. A slight wobble means a slight problem.
However, a serious wobble indicates a more serious problem.
Most of the time this problem starts out as a slight vibration
and progresses to a serious wobble. The probable causes are:
1. Tires need balancing. 2. Tires are worn. 3. The wheel is
bent or damaged. 4. The wheel lug nuts are loose. 5. There are
worn or damaged steering parts.
are wearing more on one edge than the other. Why?
You notice that the tires are very worn on the inside or outside
edge. The other edge and the center seem to have plenty of tread
left. The probable causes are: 1. Wheel-alignment problems,
excessive camber. 2. Wheel-alignment problems, incorrect toe.