Chapter 15 Constant-Velocity Axle Problems, Troubleshooting, and Service 291
Copyright by Goodheart-Willcox Co., Inc.
"Clunk"
"Clunk"
Figure 15-2. Turning the wheels from side to side will change
the loads on the CV axles, isolating noises from loose or worn
parts. Braking and accelerating may also help isolate the noise.
(Chrysler)
Most leaks from the CV axle system show up as grease
or oil splattered on the underside of the vehicle near the
leaking boot or seal. Grease may also be found on the boot
or seal itself. Leaking seals may leave a trail of grease or oil
that originates under the seal. If you squeeze a CV joint
boot and hear air escaping, there is a hole in the boot or a
loose clamp. Leaking boots and seals should be replaced
promptly.
CV Axle Safety Precautions
CV axles rotate at high speeds and can cause severe
damage. When checking for CV axle problems, always
keep the following safety precautions in mind:
If you are running the vehicle on a lift, always stay
away from the spinning axles.
When spinning the axle shafts with the vehicle on a
lift, always support the lower control arms so the front
wheels are at or near their normal position in relation
to the vehicle body. Allowing the wheels to hang
while being driven will cause the CV joints to drive
through excessive angles and could cause a joint to
bind, break, or fly apart violently.
When testing a front-wheel drive vehicle on a lift,
never exceed a speedometer reading of 30 mph (48
km/h).
If you road test the vehicle to check CV axle opera-
tion, always choose uncongested areas and obey all
traffic regulations. This will help prevent accidents.
Road Testing
It is often necessary to road test a vehicle to determine
the exact source of a problem. Often, a problem cannot be
duplicated in the shop, and a road test must be conducted.
When performing a road test, try to isolate CV axle
problems from engine, transaxle, tire, and other vehicle
problems. Rumbling or roaring noises that increase and
decrease only slightly with vehicle speed are usually
caused by bad bearings. Vibrations that cycle according to
vehicle speed generally indicate CV axle problems, not
engine or transmission trouble.
Many clunking or popping noises in the CV axle can
be diagnosed by driving the vehicle in a quiet parking lot.
As the vehicle moves slowly forward, turn the wheels
sharply from side to side, Figure 15-2. This will help
isolate many noises. Applying the brakes with varying
force may also help you to isolate noises. Remember to
check carefully to eliminate the steering or suspension
system as the source of the noises.
CV Axle Removal
Figure 15-3 shows the parts of a typical CV axle
assembly. These components must generally be removed
from a vehicle when the CV joint, axle shaft, boot, or
wheel bearing requires service. Almost all CV axle and
wheel bearing repairs require that the axle be removed
from the vehicle.
The CV axles must be removed from the transaxle
before removing the transaxle from a vehicle. On many
front-wheel drive vehicles, the engine and transaxle must
be removed as a unit. Therefore, the CV axles must often
be removed before the engine can be removed. In many
cases, the CV axles can be pulled from the transaxle with-
out removing them from the wheel hub and bearing assem-
blies.
There are many variations to the basic CV axle design.
The following procedure provides a general guide for
removing most common CV axles. Always consult the
manufacturer’s service manual for the exact removal
procedures.
1. Disconnect the vehicle’s battery negative cable.
2. Place the vehicle transaxle in Neutral.
3. Raise the vehicle and support it on approved jack
stands. With some designs, you may want to loosen
the stub shaft nut before raising the wheels off the
floor. Remove the wheel from the wheel hub on the
side to be serviced.
4. Cover the outer CV joint boot with a shop cloth, tape,
or a boot protector. See Figure 15-4. This will help
prevent damage to the boot. If needed, remove the tie
rod end nut and use a ball joint separator to free the
tie rod end from the steering knuckle, Figure 15-5.
5. Remove the stub shaft nut cotter pin, and then remove
the stub shaft nut, Figure 15-6. A few vehicles have
left-hand threads on the right stub shaft. To remove the
nut, it must be turned in a clockwise direction. Always
check the service information before trying to remove
the stub shaft nut.