automotive drive axles constant velocity (cv) types
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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
rotatingAxle 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
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.
Front Wheel Drive Issues
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.
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.
Front Wheel Drive Issues
Torque Steer Remedies
Add an intermediate shaft
Torque Steer Remedies
Vibration dampers - Sometimes used to stabilize the shaft as it spins.
Unequal length half-shafts - Usually constructed differently to reduce torque steer.
Torque Steer Remedies
Types of Drive Axles
Equal length shafts Used to reduce torque
steerVibration dampers
Sometimes used to dampen vibrations in the driveline
Unequal length half-shafts 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 TypesBall-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 JointsBall-type (Double-offset) Joint
Is similar to a Rzeppa joint but has elongated grooves in the inner race
Inboard CV Joints
Tripod-type jointHas 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, angular-contact 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
The axle nut not only secures the end of the axle but it also sets the wheel bearing pre-load.
FWD Wheel Bearing Styles
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
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.
Diagnosing CJ Joints & Axles
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 bentMove the shaft, wheels, and other
components to check for looseness
Visual Inspection
Possible Reasons for CV-Boot Failure
Cuts or tears from foreign objectsAccident damageImproper towing hook-up or service
techniquesIce forming around bootDeteriorationClamp 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 noiseHas a yoke welded to each endUniversal joints are used to connect to
pinion flange yoke and sleeve yokeMay 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 JointCharacteristics
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 JointCharacteristics
Universal JointPhasing
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
Double Cardan Type: Sometimes referred to as a Constant Velocity universal joint. Used on Luxury RWD cars … and PU trucks
Universal Joints
Universal Joint Designs (cont’d)
Slip Yolk Allows for changes
in driveshaft length caused by suspension travel
Components include:Transmission output
shaftThe slip jointA yoke and U-jointThe driveshaft
Type A Clips
Type B Clips
Methods of MountingUniversal Joints
Bearing plateCap and boltThrust plateU-boltWing bearingStrap
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 lubricationPushing another carTowing a trailerChanging gears abruptlyCarrying heavy loadsBeating the heck out of your car
Inspecting the Drive Shaft
Check for fluid leaksCheck the U-joints for signs of rust or
leakageCheck 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 marksTorque 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
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 Disassembling a U-Joint
Tips for Assembling a U-Joint
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 debrisBalance weights fallen offDirt or mud stuck on drive shaftUndercoating 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 debrisBalance weights fallen offDirt or mud stuck on drive shaftUndercoating sprayed on drive shaftImproper 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 indicatorMeasure at the center and at both ends of
shaftRefer to manufacturer’s specifications for
acceptable runoutReplace 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 housingHotchkiss-type drive shafts are commonly used today
Universal joints can be single or double Cardan joints
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
Summary (cont’d)