CHAPTER EIGHT
Contents
1. The differential is mounted to the frame Most use two half shafts with CV joints Some use one half shaft and one solid axle Coil springs attachment Differential bushing in L H housing s DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Steps in Diagnosis e Talk to the customer Find out under what condition the problem occurs e Road test Most problems show up as vibrations or noises Try to verify that the 4WD system is causing the problem e Perform a detailed inspection DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning 4WD Noise and Vibration Diagnosis e Noise or vibration is most noticeable at high speed Usually caused by a transfer case problem bent drive shaft or bad wheel bearings e Noise or vibration is most noticeable at low speed Usually caused by bad U joints e Noise or vibration is most noticeable while turning Usually caused by worn outboard axle joints DELMAR b a CENGAGE Learnin g Copyright 2011 Delmar Cengage Learning 4WD Noise and Vibration Diagnosis cont d e Noise or vibration is most noticeable when traveling over bumps Usually caused by suspension components e Noise or vibration 1s most noticeable with changes in throttle position Usually caused by U joints or worn driveshaft splines 2 DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Shi2. that the hub on the opposite side of the axle is not disengaging Locking hubs can be checked by rotating the brake drum or rotor and turning the hub selector into the locked position 2 DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Transfer Case Service Guidelines e Always refer to the service manual e Label all wires before disconnecting them e Replace all sealing gaskets e Inspect all parts and replace any that are worn or damaged e Tighten all fasteners to the proper torque 2 DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Front Axle and Hub Service Guidelines e Most front axles are serviced like those in 2WD systems e Follow the recommended procedure for servicing 4WD hubs e Some hubs are not serviceable and must be replaced 2 DELMAR a CENGAGE Learning Side bearing adjuster washer mi Boral 8 i 90 Pigs a wate Hara Mts ars Pinion adi gt thrust washer Pinion Inner rear bearin g bearing L she ace Drive pinion eo Pinion height adjustment race fa Fos Pinion bearing adjusting spacer Copyright 2011 Delmar Cengage Learning Wheel Bearing Service Guidelines e Wheel bearings must be serviced regularly e Always adjust the gt i wheel bearings during s assembly wo f e Tighten the outer X P N n bearing lock nut to O O specifications Meri ahe
3. CHAPTER EIGHT Four Wheel Drive Systems Classroom and Shop Manual 2 DELMAR a CENGAGE Learning Objectives e Explain the advantages and disadvantages of four wheel drive e Use the correct terminology when discussing four wheel drive systems e Describe the different designs of four wheel drive systems and their applications DELMAR b a CENGAGE Learnin g Copyright 2011 Delmar Cengage Learning Objectives cont d e Compare and contrast the components of part and full time four wheel drive systems e Describe the operation of various transfer case designs and their controls e Identify the differences in operation between manual and automatic locking front wheel hubs 2 DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Objectives cont d e Identify the suspension requirements of vehicles equipped with four wheel drive 2 DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Why Four Wheel Drive e Advantages Improved traction and handling Able to transmit more power to the wheels e Disadvantages Higher initial cost and weight Requires special service and maintenance s DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning 4WD Designs e RWD vehicles equipped with an added transfer case a front drive shaft a front differential and front drive axles Second Central Engine drive s
4. Difficult to clearly define the difference between 4WD e Primary difference is the transfer case 4WD offers two speed ratios high and low AWD does not have a low e Constantly provides power to all four wheels Does not give the driver the option of 2WD or 4WD 2 DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning 4WD Shift Controls e Electric switch or shift lever Allows the driver to select which axles receive power Power can be directed to e all four wheels e two wheels e none neutral Some vehicles have a low speed range that can be selected s DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Transfer Case Modes of Operation Annulus gear turns freely Pinion gear e Ranges available with a part time transfer case ms Neutral D Two wheel drive high Four wheel drive high Four wheel drive low Drive sprocket carrier gear and output shaft are locked together Input shaft and planetary case are locked shaft chain driven Power output to rear wheels High speed range Lockup device 2 DELMAR a CENGAGE Learning No power out to rear whee Input shaft and planetary case are locked Power output to rear wheels High speed range m Lockup device ive sprocket carrier gear and output shaft are locked together a Power output to tront wheel output shaft chain
5. P Is used on full time 4WD systems m Link 2 Convex Is very efficient at plate pins continuous high speeds s DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Planetary Gear Drive Operation e Neutral The ring gear and pinion gears rotate freely and no power is transmitted e Gear reduction With the ring gear held the sun gear drives the planetary gears and carrier at a reduction in speed DELMAR a CENGAGE Learning Input shaft and planetary case are locked rr Power output to rear wheels FJ High speed range i Lockup device Copyright 2011 Delmar Cengage Learning Planetary Gear Drive Operation cont d e High gear direct The ring gear and planetary gears are locked together and the entire assembly turns as a unit providing for direct drive DELMAR b a CENGAGE Learnin g Copyright 2011 Delmar Cengage Learning Locking Hub Operation e Manual hubs The hubs are at the wheel and must be turned by hand The hubs are unlocked in 2WD e Automatic hubs The hubs are self locking Some hubs unlock when vehicle is driven in reverse Some unlock when 4WD is disengaged e DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning 4WD Suspension Types e Solid axle Uses arear axle design The ends of the axle have steering knuckles for steering e Independent
6. busin 2 DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Effects of Vehicle Modifications e Installing larger tires and lift kits Alters vehicle handling by changing unsprung weight Increases steering effort Causes a rough ride May cause vehicle to wander and vibrate 2 DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Maintenance Tips e Check the fluid level often e Check for fluid contamination any time the vehicle has been driven through deep water e Use only the recommended lubricant oanp D e Always follow the proper TERT aa aT TR towing a procedures 2 DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Summary e There are many advantages to 4WD systems including better traction and handling e 4WD systems can be classified as either part time full time or on demand 2 DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Summary cont d e Most transfer cases use a chain drive anda planetary gearset e 4WD system diagnosis includes talking to the customer road testing for abnormal noises or vibrations and visually inspecting the system 2 DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Summary cont d e System inspection and service includes checking the transfer case drive shafts axle assemblies steering system suspens
7. driven Power input Power output to rear wheels o o High speed range issembly moves forward Lockup device E tow sangeepoed Copyright 2011 Delmar Cengage Learning Transfer Case Modes of Operation cont d e Ranges available with a full time transfer case Two wheel drive high Four wheel drive high Four wheel drive low 2 DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Transfer Case Modes of Operation cont d e Ranges available with a part time full time transfer case Two wheel drive high Full time four wheel drive high Part time four wheel drive low DELMAR b a CENGAGE Learnin g Copyright 2011 Delmar Cengage Learning Types of Transfer Cases e Drive chain design Has less weight to improve fuel economy Is usually used with planetary gearsets Is the most common design e Gear type Uses only gearsets to transfer power s DELMAR a CENGAGE Learning R low gear Rear output shaft Rear idler gear Front drive output shaft EEJ m i Front drive low gear 4WD clutch Copyright 2011 Delmar Cengage Learning Drive Chain Variations e Round pin style lt lt Pp a P a Pp Is commonly used in transfer cases on part time C x 4WD vehicles O Can handle higher loads an e Pin and rocker joint design 4 pra PpPra Pp
8. fting Problems e Common complaint on all transfer cases is the inability to go from 4WD to 3WD It is common for these units to get spline locked e If transfer case jumps out of gear suspect improperly adjusted shift linkage loose mounting bolts or brackets worn front rear drive shaft slip yokes or a damaged sliding clutch hub 2 DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Common Sources of Leaks e Driveshaft seals at the Rear output transfer case shaft seal e Driveshaft seals at the differentials e Front or rear axle seals Input shaft seal e Threads at the transfer case fill plug Front output shaft seal 2 DELMAR kid a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Fluid Leak Service Procedures e Use only gaskets and seals recommended by the manufacturer e Never use sealant in place of a gasket e Always use the proper tools to install a seal e Make sure the surface that the seal rides on is smooth 2 DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Transfer Case Inspection e Vacuum controlled transfer case Verify that the engine is producing at least 15 inches of vacuum e Mechanically controlled transfer case Make sure the shift linkage is tight and lubricated 2 DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Drive Shaft Inspection e Check the U j
9. haft bearing e FWD vehicles with an eis added transfer case a rear drive shaft and a rear axle Rear Some use a center Taster Pn differentia differential instead of a transfer case 2 DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning 4W D Components e Transfer case Transmits power from the transmission to the front and rear drive shafts e Drive shafts Connect to the front and rear differentials e Universal joints or CV joints Are used to connect front axles to the wheel hubs s DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning 4WD Systems e Part time systems Can be operated in either two wheel drive or four wheel drive Selection of two or four wheel drive is done by a shifter electric switch or locking hubs e Full time systems Cannot be selected out of four wheel drive DELMAR a CENGAGE Learning Heavy duty Dana 44 axle assembly with TRU LOK locking differential 2H 4L ROCK TRAC NV2410R transfer case locking differential Copyright 2011 Delmar Cengage Learning 4WD Systems cont d e On demand systems Automatically controlled Typically drives one axle until some wheel slip 1s detected Some systems send torque to opposite axle when slip is anticipated 2 DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning All Wheel Drive Systems e
10. ion system and the wheels and tires DELMAR b a CENGAGE Learnin g Copyright 2011 Delmar Cengage Learning
11. oints for looseness by twisting and shaking them e Check the slip joints for looseness by moving them up and down e Check the splines for wear by rotating the drive shaft c e DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Suspension System Inspection e Check the standing height of the vehicle and compare it _ Upper to the factory Manes specifications e Check the spring Fiedigutde pads for damage eon Dust shield e Check ball joints or king pins for looseness e Check the shocks and sway bars for looseness or damage Piston rod Piston Relief valve Lower mounting e DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Steering System Inspection e Check the steering linkage for damage e Check for play in the steering system e Verify that the front suspension is aligned properly e Check the steering damper for wear leaks or damage Idler arm Adjusting sleeve Outer tie rod 2 DELMAR a CENGAGE Learning Copyright 2011 Delmar Cengage Learning Wheel and Bearing Inspection Check the adjustment of the wheel bearings e Check the tires for proper size and inflation e Check for tire radial runout e Check for abnormal tire wear 2 DELMAR a CENGAGE Learning Axle Hub Diagnosis e Front hubs may make a ratcheting sound when water or dirt has entered the hub and contaminated the lubricant e May indicated
Download Pdf Manuals
Related Search