Automotive Drive Axles Constant Velocity (CV) Types.

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.

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.

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


Vibration dampers - Sometimes used to stabilize the shaft as it spins.

Unequal length half-shafts - Usually constructed differently to reduce torque steer.


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

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 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.


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.


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

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)

Automotive Drive Axles Constant Velocity (CV) Types.

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