Automotive Drive
Axles
Constant Velocity (CV) Types
Drive Axle Components (fwd)
Drive Axle Components (rwd)
Outer CV-joint
Allows wheels to steer while
axle is rotating
Inner CV-joint
Allows for suspension
changes while axle is rotating
Axle shaft
Transmits power from inner
to outer CV-joint
ABS Speed Sensor
Some axle shafts have an exciter ring welded to the
outboard CV joint for ABS operation. During removal
and service of this style of axle extreme care must be
used not to damage or move this ring.
Drive Axle Components
Outer CV-joint
Allows wheels to steer while axle is rotating
Inner CV-joint
Allows for suspension changes while axle is rotating
Axle shaft
Transmits power from inner to outer CV-joint
Front Wheel Drive
Issues
With the engine mounted transversely, the
transaxle sits to one side of the engine
compartment. Thus, one axle must be
longer than the other.
Front Wheel Drive
Issues
Front Wheel Drive
Issues
Torque Steer - occurs when the CV joints on
one drive shaft operate at different angles
from those on the other shaft.
The joints on the longer shaft almost always
operate at less of an angle than those on the
shorter shaft.
With an open differential the shaft with the
least resistance will receive more torque.
What?
1. A longer shaft will flex more thus
being more forgiving at its outer
angles.
2. A longer shaft will operate at more
of an angle thus reducing the angles of
the joint.
Front Wheel Drive
Issues
When the differential sends power to the
wheels, the longer shaft will have less
resistance because the CV joints are
operating at less of an angle. Most of the
engines power will be sent to that side. This
phenomenon results in what is called torque
steer.
Torque Steer Remedies
Add an intermediate shaft
Torque Steer Remedies
Vibration dampers - Sometimes used to
stabilize the shaft as it spins.
Torque Steer Remedies
Unequal length half-shafts - Usually constructed
differently to reduce torque steer.
Types of Drive Axles
Equal length shafts
Used to reduce torque
steer
Vibration dampers
Sometimes used to
dampen vibrations
in the driveline
Unequal length halfshafts
Usually constructed
differently to prevent
torque steer
Front wheel drive shafts turn
at approximately 1/3 the
speed of rear wheel drive
shafts.
Why?
Benefits?
CV-Joint Types
 Outboard joint
Does not move in and out to change shaft length
Fixed joint
 Inboard joint
Changes in length to allow movement of the
suspension
Plunging joint
Outboard Joint Movement
CV-Joint Types
Inboard Joint Movement
CV-Joint Types
CV-Joint Types
Ball-type CV-joint
Was named after its designer, A.H. Rzeppa
Uses three to six steel balls held together by a steel
cage
The balls ride in a socket to allow rotation and
turning
Is used in most front-wheel-drive vehicles
Rzeppa Joint Exploded View
Rzeppa Joint - Exploded
View
CV-Joint Types
Outboard Joints (cont’d)
Tripod-type joint
Uses a central hub (tripod) with three trunnions
Has roller bearings that ride on the trunnions
The outer surface of bearings ride in the joint or
“tulip” housing
Allows for greater angles
Tripod Joint
Outboard Joint Movement
Inboard Plunging Tripod
Inboard Plunging Tripod
Inboard CV Joints
Ball-type (Double-offset) Joint
Is similar to a Rzeppa joint but has
elongated grooves in the inner race
Inboard CV Joints
Tripod-type joint
Has longer grooves than a fixed-type joint
to allow
for plunging.
Inboard CV Joints
Cross Groove CV Joint
•The grooves in the outer race are cut at
an angle to allow for better movement.
CV-Joint Types
Inboard Joint Movement
CV-Joint Types
Outboard joint types
Rzeppa fixed tripod
Inboard joint types
Double-offset
Plunging tripod
Cross-groove plunge
joint
CV-Joint
All CJ joints have a rubber, plastic or
neoprene boot to protect the internal
parts.
The boots are fastened by clamps at
either end.
All CV joints must be lubricated.
CV joint grease differs from standard
wheel bearing or chassis grease. They
cannot be interchanged!
CV-Joint
Constant velocity joints are called as such
because they are designed to transfer a
uniform torque and a constant speed
through a wide variety of angles.
FWD Wheel Bearing Styles
 Double-row, angularcontact
bearings
Are used on most General
Motors, DaimlerChrysler,
and European cars
Have two rows of ball
bearings
located next to each other
 Opposed tapered-roller
bearings
Are used on Fords and
most Asian cars
FWD Wheel Bearing Styles
The axle nut not only secures the end of
the axle but it also sets the wheel bearing
pre-load.
Diagnosing CJ Joints &
Axles
Bad CV joints will generally make a clunking or
clicking noise. Outer joints will make noise on turns.
Diagnosing CJ Joints &
Axles
Bad CV joints will generally make a clunking or
clicking noise. Inner joints will make noise over
bumps.
Perform a Road Test
Drive the car under various conditions such as
accelerating, coasting, turning, and weaving
side to side
Listen for clicking or clunking, especially while
turning
Feel for shudder, shimmy, vibration, or any
other abnormalities
Diagnosing CJ Joints &
Axles
Do not confuse CV joint noises with outer
wheel bearing noises.
CV joint noises will be more noticeable at
slower speeds.
Wheel bearing noises will have a higher
pitch grind or whine. They will also be
more noticeable at higher speeds on
turns.
Visual Inspection
Check out all other problem
areas before assuming that
the problem is being caused
by the axle assembly
Check the CV-boots for
tears and grease leaks
Check the shafts for damage or being bent
Move the shaft, wheels, and other components
to check for looseness
Visual Inspection
Possible Reasons for CVBoot Failure
Cuts or tears from foreign objects
Accident damage
Improper towing hook-up or service techniques
Ice forming around boot
Deterioration
Clamp failure
Off-Car Axle Inspection
 Be careful not to
overtighten the shaft
in the vise
 Look for cracks, chips,
pits, or rust on all
components
 Check the joint for
sticking while plunging
it in and out
 Check for discoloring
usually caused by heat
Boot Replacement Tips
 Mark the location of the
joint to the shaft
 Inspect the grease for
contamination
 Make sure the new boot
clamps are secure
 Use a dull screwdriver
to remove trapped air
from the boot
CV-Joint Replacement Tips
Clean the joint thoroughly so a complete
inspection can be made
Refer to the service manual to find out how the
joint is retained to the shaft
Pack the new joint using all of the lubricant
supplied
FWD Wheel Bearing
Inspection
Excessive play inspection
Usually checked by pulling outward at the top of the
tire and pushing inward at the bottom with the
vehicle supported under the control arm
Noise inspection
Bearing noise will often increase when the vehicle is
turned
Front Wheel Drive Service
Anytime a front axle or wheel bearing is
serviced the axle retaining nut MUST be
torqued to manufacturer specifications.
Rear Wheel Drive Axle
Shafts
Drive Shaft Purposes
Transmits power from the
transmission to the
differential
Allows the transmission and
the rear axle assembly to be
at different heights
Allows the rear axle to move
up and down while
maintaining a connection to
the transmission
Drive Shaft Features
Can be made of steel, aluminum, or composite
material
May have cardboard liner to reduce noise
Has a yoke welded to each end
Universal joints are used to connect to pinion
flange yoke and sleeve yoke
May have balance weights attached
Drive Shaft Designs
Hotchkiss design
Can be one piece or two
piece
The shaft and joints are
external
Two piece Design
Uses a carrier (center)
bearing to stabilize the
center of the driveshaft
Drive Shaft Designs
Torque tube: uses rigid tube with no universal joints
Flexible type: A flexible steel rope; rarely used today
Universal Joints
Are sometimes
referred to as
Cardan, Spicer,
cross, four-point, or
Hooke joints
Allow for angle
changes between
the drive shaft, the
transmission output
shaft, and the rear
axle housing
Universal Joint
Characteristics
Speed variations
While operating at an
angle, U-joints speed
up and slow down
twice per revolution
Joint phasing
The vibrations caused
by one U-joint are
transmitted to the
other one
Universal Joint
Characteristics
Universal Joint
Phasing
Universal Joint
Characteristics (cont’d)
Canceling angles
The angle of the front U-joint is offset by the rear
one
The correct angle must be maintained to minimize
vibration
Universal Joint Designs
Single universal joint
Sometimes known as
single Cardan/Spicer
Universal joint
Consists of a cross and
four needle bearings
Double Cardan joint
Consists of two single
U-joints joined by a
center yoke and a ball
and socket
Universal Joint Designs
Universal Joint Designs
Universal Joints
Double Cardan Type: Sometimes referred
to as a Constant Velocity universal joint.
Used on Luxury RWD cars
… and PU trucks
Universal Joint Designs
(cont’d)
Slip Yolk
Allows for changes in
driveshaft length
caused by suspension
travel
Components include:
Transmission output
shaft
The slip joint
A yoke and U-joint
The driveshaft
Type A Clips
Type B Clips
Methods of Mounting
Universal Joints
Bearing plate
Cap and bolt
Thrust plate
U-bolt
Wing bearing
Strap
Universal Joint
Maintenance
Most factory-installed universal joints are sealed
and don’t require periodic lubrication
After-market replacement joints are equipped
with a grease fitting and must be greased
periodically
Drive Shaft Problem
Diagnosis
Road testing
Vehicle should be driven while accelerating and
decelerating as well as at various steady speeds
Vibrations caused by worn U-joints usually occur
while accelerating
Types and Causes of
Vibrations
High speed vibrations
Usually caused by driveshaft
imbalance
Vibrations during acceleration
Usually caused by worn double
Cardan joint ball and socket
Low speed vibrations
Usually caused by improper
operating angles
Noise Diagnosis
Clunking noise while accelerating from a dead
stop
Usually caused by worn or damaged U-joint
Can be caused by problems including excessive
clearance between slip joint and extension housing
Squeaking noise
Often caused by worn or poorly lubricated U-joint
Reasons for Universal
Joint Failure
Lack of lubrication
Pushing another car
Towing a trailer
Changing gears abruptly
Carrying heavy loads
Beating the heck out of your car
Inspecting the Drive Shaft
Check for fluid leaks
Check the U-joints for signs of rust or leakage
Check for movement in the joint while trying to
turn the yoke and the shaft in opposite
directions
Check the drive shaft for dents, missing
weights, and undercoating or dirt
Check for binding U-joints
Tips for Removing and
Installing a Drive Shaft
Always mark the pinion
flange and the end yoke
before disassembly
Use a plug on the
transmission extension
housing to prevent fluid
loss
Line up all index marks
Torque bolts to
manufacturer’s
specifications
Tips for Disassembling a
U-Joint
Index the joint’s
components before
disassembly
Remove all retaining
rings before pressing
on the spider
Use a U-joint tool kit,
socket and vise, c-clamp,
or press to press the
spider from the yoke
Tips for Disassembling a
U-Joint
Most General Motors Universal Joints are
kept in place with organic or fiberglass
retainers
The caps must be heated with a torch to
“pop” the retainers free
Tips for Assembling a UJoint
Clean all components before
assembly
Turn the spider while
tightening to ensure
the trunions move freely on
the bearings
Take care not to tear the
bearing
seal during assembly
Fill new joint with grease
(if equipped with a fitting)
Causes of Drive Shaft
Imbalance
Damage from rocks and debris
Balance weights fallen off
Dirt or mud stuck on drive shaft
Undercoating sprayed on drive shaft
Measuring Operating Angle
 Make sure the vehicle is empty and the gas tank
is full
 Use inclinometer
to measure
U-joint angles
 Follow the service manual procedures
 Compare front
and rear angles
 The difference between the two angles is the operating
angle
Measuring Operating Angle
The difference between the two angles is the operating angle
Causes of Drive Shaft Imbalance
Damage from rocks and debris
Balance weights fallen off
Dirt or mud stuck on drive shaft
Undercoating sprayed on drive shaft
Improper service
Steps for Checking
Imbalance
1. Set up vehicle to be run on
a lift
2. While vehicle is running, use
chalk to mark the high spot
on the shaft
3. Stop vehicle and install two
large hose clamps to the
shaft with the screw
assembly opposite the chalk
mark
4. Run engine to the desired
speed again
Steps for Checking
Imbalance (cont’d)
5. If the vibration is gone,
road test the vehicle
6. If the vibration is still
felt, rotate the clamps
away from each other in
equal amounts and
repeat test
7. Repeat the procedure
until
no vibration is felt
Measuring Drive Shaft
Runout
Use a dial indicator
Measure at the center and at both ends of shaft
Refer to manufacturer’s specifications for
acceptable runout
Replace the shaft if runout is greater than
allowed
Summary
The purpose of the drive shaft is to transmit
power from the transmission to the rear end
while allowing for changes in suspension height
Universal joints allow for angle changes
between the drive shaft, the transmission
output shaft, and the rear axle housing
Hotchkiss-type drive shafts are commonly
used today
Universal joints can be single or double
Cardan joints
Summary (cont’d)
Universal joints and drive shafts require little
maintenance
Diagnosing drive shaft concerns usually
involves a road test and a visual inspection
Servicing drive shaft components requires
following specific service procedures
Several checks can be performed, including
balance, runout, and operating angle