1. CHAPTER 16 Drive Axle Shaft and CV Joint Service

2. OBJECTIVES After studying Chapter 16, the reader will be able to:
Prepare for ASE Suspension and Steering (A4) certification test content area “C” (Related Suspension and Steering Service).
Explain how to perform a U-joint inspection.
List the steps necessary to replace a U-joint.
Explain how to perform a measurement of the working angles of a U-joint.
Describe the service procedures for replacing CV joints and boots.
Describe the routine maintenance service procedures required for drive axle shafts and universal CV joints.

3. KEY TERMS Inclinometer Pin bushings Pinch bolt Spline bind
Synthetic retainers
Torque prevailing nut
U-joints

4. INTRODUCTION
The driveshaft must travel up and down as the vehicle moves over bumps and dips in the road while rotating and transmitting engine power to the drive wheels.
The driveshaft and universal joints should be carefully inspected whenever any of the following problems or symptoms occur:
Vibration or harshness at highway speed
A clicking sound whenever the vehicle is moving either forward or in reverse
A clunking sound whenever changing gears, such as moving from Drive to Reverse

5. The Squeaking Pickup Truck
The owner of a pickup truck complained that a squeaking noise occurred while driving in reverse. The “eeeee-eeeee-eeee” sound increased in frequency as the truck increased in speed, yet the noise did not occur when driving forward.

6. The Squeaking Pickup Truck
Because there was no apparent looseness in the U-joints, the service technician at first thought that the problem was inside either the transmission or the rear end. When the driveshaft was removed to further investigate the problem, it became obvious where the noise was coming from. The U-joint needle bearing had worn the cross-shaft bearing surface of the U-joint. The noise occurred only in reverse because the wear had occurred in the forward direction, and therefore only when the torque was applied in the opposite direction did the needle bearing become bound up and start to make noise. A replacement U-joint solved the squeaking noise in reverse.

7. The Squeaking Pickup Truck
FIGURE 16–1 Notice how the needle bearings have worn grooves into the bearing surface of the U-joint.

8. DRIVESHAFT AND U-JOINT INSPECTION
The driveshaft should be inspected for the following:
Any dents or creases caused by incorrect hoisting of the vehicle or by road debris.
Undercoating, grease, or dirt buildup on the driveshaft can cause a vibration.
Undercoating should be removed using a suitable solvent and a rag. Always dispose of used rags properly.

9. DRIVESHAFT AND U-JOINT INSPECTION
FIGURE 16–2 All U-joints and spline collars equipped with a grease fitting should be greased four times a year as part of a regular lubrication service. (Courtesy of Dana Corporation)

10. DRIVESHAFT AND U-JOINT INSPECTION
FIGURE 16–3 Many U-joints require a special grease gun tool to reach the grease fittings. (Courtesy of Dana Corporation)

11. DRIVESHAFT AND U-JOINT INSPECTION
FIGURE 16–4 Always mark the original location of U-joints before disassembly.

12. DRIVESHAFT AND U-JOINT INSPECTION
FIGURE 16–5 Two types of retaining methods that are commonly used at the rear U-joint at the differential. (Courtesy of Dana Corporation)

13. DRIVESHAFT AND U-JOINT INSPECTION
FIGURE 16–6 The best way to check any U-joint is to remove the driveshaft from the vehicle and move each joint in all directions. A good U-joint should be free to move without binding. (Courtesy of Dana Corporation)

14. U-JOINT REPLACEMENT
All movement in a U-joint should occur between the trunnions and the needle bearings in the end caps.
The end caps are press-fit to the yokes, which are welded to the driveshaft.
Three types of retainers are used to keep the bearing caps on the U-joints: the outside snap ring, the inside retaining ring, and injected synthetic (usually nylon).

15. U-JOINT REPLACEMENT
FIGURE 16–7 Typical U-joint that uses an outside snap ring. This style of joint bolts directly to the companion flange that is attached to the pinion gear in the differential.
FIGURE 16–8 A U-joint that is held together by nylon and usually requires that heat be applied to remove from the yoke.

16. U-JOINT REPLACEMENT
FIGURE 16–9 Use a vise and two sockets to replace a U-joint. One socket fits over the bearing cup and one fits on the bearing to press fit the cups from the crosspiece.

17. Use Tape to Be Safe
When removing a driveshaft, use tape to prevent the rear U-joint caps from falling off. If the caps fall off the U-joint, all of the needle bearings will fall out and scatter over the floor.

18. Use Tape to Be Safe
FIGURE 16–10 Taping the U-joint to prevent the caps from coming off.

19. U-JOINT REPLACEMENT
FIGURE 16–11 A special tool being used to press apart a U-joint that is retained by injected plastic. Heat from a propane torch may be necessary to soften the plastic to avoid exerting too much force on the U-joint.

20. U-JOINT REPLACEMENT
FIGURE 16–12 Removing the worn cross from the yoke.

21. U-JOINT REPLACEMENT
FIGURE 16–13 When installing a new U-joint, position the grease fitting on the inboard side (toward the driveshaft tube) and in alignment with the grease fitting of the U-joint at the other end.

22. U-JOINT WORKING ANGLES
Unequal or incorrect U-joint working angles can cause severe vibrations.
Driveshaft and U-joint angles may change from the original factory setting due to one or more of the following:
Defective or collapsed engine or transmission mounts
Defective or sagging springs, especially the rear springs due to overloading or other causes
Accident damage or other changes to the chassis of the vehicle
Vehicle modification that raises or lowers the ride height

23. U-JOINT WORKING ANGLES
FIGURE 16–14 The working angle of most U-joints should be at least 1/2 degree (to permit the needle bearing to rotate in the U-joints) and should not exceed 3 degrees or a vibration can occur in the driveshaft, especially at higher speeds. The difference between the front and rear working angles should be within 1/2 degree of each other.

24. U-JOINT WORKING ANGLES
FIGURE 16–15 An inclinometer with a magnetic base is being used to measure the angle of the driveshaft at the rear U-joint.

25. U-JOINT WORKING ANGLES
FIGURE 16–16 Placing a tapered metal wedge between the rear leaf spring and the rear axle pedestal to correct rear U-joint working angles.

26. U-JOINT WORKING ANGLES
FIGURE 16–17 A transmission oil pan gasket leak allowed automatic transmission fluid (ATF) to saturate the rear transmission mount rubber, causing it to collapse. After replacing the defective mount, proper driveshaft angles were restored and the driveline vibration was corrected.

27. CV JOINT DIAGNOSIS
When a CV joint wears or fails, the most common symptom is noise while driving.
An outer fixed CV joint will most likely be heard when turning sharply and accelerating at the same time.
This noise is usually a clicking sound.
While inner joint failure is less common, a defective inner CV joint often creates a loud clunk while accelerating from rest.
To help verify a defective joint, drive the vehicle in reverse while turning and accelerating.
This almost always will reveal a defective outer joint.

28. Quick and Easy Backlash Test
Whenever a driveline clunk is being diagnosed, one possible cause is excessive backlash (clearance) between the ring gear teeth and differential pinion teeth in the differential. Another common cause of excessive differential backlash is too much clearance between differential carrier pinion teeth and side gear teeth. A quick test to check backlash involves three easy steps:
Hoist the vehicle on a frame contact lift, allowing the drive wheels to be rotated.
Have an assistant hold one drive wheel and the driveshaft to keep them from turning.
Move the other drive wheel, observing how far the tire can rotate. This is the amount of backlash in the differential; it should be less than 1 in. (25 mm) of movement measured at the tire.

29. REPLACEMENT SHAFT ASSEMBLIES
Front-wheel-drive vehicles were widely used in Europe and Japan long before they became popular in North America.
The standard repair procedure used in these countries is the replacement of the entire drive assembly if there is a CV joint failure.
Replacement boot kits are rarely seen in Europe because it is felt that even a slight amount of dirt or water inside a CV joint is unacceptable.
Vehicle owners simply wait until the joint wear causes severe noise, and then the entire assembly is replaced.

30. CV JOINT SERVICE
The hub nut must be removed whenever servicing a CV joint or shaft assembly on a front-wheel-drive vehicle.
Since these nuts are usually torqued to almost 200 lb-ft (260 N-m), keep the vehicle on the ground until the hub nut is loosened and then follow these steps.

31. CV JOINT SERVICE
FIGURE 16–18 The hub nut must be removed before the hub bearing assembly or drive axle shaft can be removed from the vehicle.

32. STEP 1 Remove the front wheel and hub nut.
CV JOINT SERVICE
STEP 1 Remove the front wheel and hub nut.
STEP 2 To allow the knuckle room to move outward enough to remove the drive axle shaft, some or all of the following will have to be disconnected:
Lower ball joint or pinch bolt
Tie rod end
Stabilizer bar link.
Front disc brake caliper.
STEP 3 Remove the splined end of the axle from the hub bearing.

33. CV JOINT SERVICE
STEP 4 Use a prybar or special tool with a slide hammer, and remove the inner joint from the transaxle.
STEP 5 Disassemble, clean, and inspect all components.
STEP 6 Replace the entire joint if there are any worn parts. Pack all the grease that is supplied into the assembly or joint.
STEP 7 Reinstall the drive axle shaft in the reverse order of removal, and torque the drive axle nut to factory specifications.

34. CV JOINT SERVICE
FIGURE 16–19 Many knuckles are attached to the ball joint on the lower control arm by a pinch bolt.

35. CV JOINT SERVICE
FIGURE 16–20 The preferred method for separating the tie rod end from the steering knuckle is to use a puller such as the one shown. A “pickle-fork”-type tool should be used only if the tie rod is going to be replaced. A pickle-fork-type tool can damage or tear the rubber grease boot. Striking the tie rod end with a hammer while holding another hammer behind the joint to shock and break the taper from the steering knuckle can also be used.

36. CV JOINT SERVICE
FIGURE 16–21 Many drive axles are retained by torque prevailing nuts that must not be reused. Torque prevailing nuts are slightly deformed or contain a plastic insert that holds the nut tight (retains the torque) to the shaft without loosening.

37. CV JOINT SERVICE
FIGURE 16–22 A special General Motors tool is being used to separate the drive axle shaft from the wheel hub bearing.

38. CV JOINT SERVICE
FIGURE 16–23 Most inner CV joints can be separated from the transaxle with a prybar.

39. CV JOINT SERVICE
FIGURE 16–24 When removing a drive axle shaft assembly, use care to avoid pulling the plunge joint apart.

40. CV JOINT SERVICE
FIGURE 16–25 If other service work requires that just one end of the drive axle shaft be disconnected from the vehicle, be sure that the free end is supported to prevent damage to the protective boots or allowing the joint to separate.

41. CV JOINT SERVICE
FIGURE 16–26 With a scribe, mark the location of the boots before removal. The replacement boots must be in the same location.

42. CV JOINT SERVICE
FIGURE 16–27 Most CV joints use a snap ring to retain the joint on the drive axle shaft.

43. CV JOINT SERVICE
FIGURE 16–28 After releasing the snap ring, most CV joints can be tapped off the shaft using a brass or shot-filled plastic (dead-blow) hammer.

44. CV JOINT SERVICE
FIGURE 16–29 Typical outer CV joint after removing the boot and the joint from the drive axle shaft. This joint was removed from the vehicle because a torn boot was found. After disassembly and cleaning, this joint was found to be OK and was put back into service. Even though the grease looks terrible, there was enough grease in the joint to provide enough lubrication to prevent any wear from occurring.

45. CV JOINT SERVICE
FIGURE 16–30 The cage of this Rzeppa-type CV joint is rotated so that one ball at a time can be removed. Some joints require that the technician use a brass punch and a hammer to move the cage.

46. CV JOINT SERVICE
FIGURE 16–31 Be sure to use all of the grease supplied with the replacement joint or boot kit. Use only the grease supplied and do not use substitute grease.

47. CV JOINT SERVICE
FIGURE 16–32 A screwdriver is shown, but a punch would be better, to keep the rotor from rotating while removing or installing the drive axle shaft spindle nut.

48. Spline Bind Cure
Driveline “clunk” often occurs in rear-wheel-drive vehicles when shifting between drive and reverse or when accelerating from a stop. Often the cause of this noise is excessive clearance between the teeth of the ring and pinion in the differential. Another cause is called spline bind, where the changing rear pinion angle creates a binding in the spline when the rear springs change in height. For example, when a pickup truck stops, the weight transfers toward the front and unloads the rear springs. The front of the differential noses downward and forward as the rear springs unload. When the driver accelerates forward, the rear of the truck squats downward, causing the drive shaft to be pulled rearward when the front of the differential rotates upward. This upward movement on the spline often causes the spline to bind and make a loud clunk when the bind is finally released.

49. Spline Bind Cure
The method recommended by vehicle manufacturers to eliminate this noise is to follow these steps:
Remove the driveshaft.
Clean the splines on both the driveshaft yoke and the transmission output shaft.
Remove any burrs on the splines with a small metal file (remove all filings).
Apply a high-temperature grease to the spline teeth of the yoke. Apply grease to each spline, but do not fill the splines. Synthetic chassis grease is preferred because of its high temperature resistance.
Reinstall the driveshaft.

50. The Vibrating Buick
The owner of a front-wheel-drive Buick complained that it vibrated during acceleration only. The vehicle would also pull toward one side during acceleration. An inspection discovered a worn (cracked) engine mount. After replacing the mount, the CV joint angles were restored and both the vibration and the pulling to one side during acceleration were solved.

51. The Vibrating Buick
FIGURE 16–33 The engine had to be raised higher to get the new (noncollapsed) engine mount installed.

52. SUMMARY
A defective U-joint often makes a clicking sound when the vehicle is driven in reverse. Severely defective U-joints can cause driveline vibrations or a clunk sound when the transmission is shifted from Reverse to Drive or from Drive to Reverse.
Incorrect driveshaft working angles can result from collapsed engine or transmission mounts.
Driveline clunk noise can often be corrected by applying high-temperature chassis grease to the splines of the front yoke on the driveshaft.
CV joints require careful cleaning, inspection, and lubrication with specific CV joint grease.

53. REVIEW QUESTIONS
List two items that should be checked when inspecting a driveshaft.
List the steps necessary to measure driveshaft U-joint working angles.
Describe how to replace a Cardan-type U-joint.
Explain the proper steps to perform when replacing a CV joint.

54. CHAPTER QUIZ
1. Two technicians are discussing U-joints. Technician A says that a defective U-joint could cause a loud clunk when the transmission is shifted between Drive and Reverse. Technician B says a worn U-joint can cause a clicking sound only when driving the vehicle in reverse. Which technician is correct?
Technician A only
Technician B only
Both Technicians A and B
Neither Technician A nor B

55. CHAPTER QUIZ
2. Incorrect or unequal U-joint working angles are most likely to be caused by ________.
A bent driveshaft
A collapsed engine or transmission mount
A dry output shaft spline
Defective or damaged U-joints

56. 3. A defective outer CV joint will usually make a ________.
CHAPTER QUIZ
3. A defective outer CV joint will usually make a ________.
Rumbling noise
Growling noise
Clicking noise
Clunking noise

57. CHAPTER QUIZ
4. The last step after installing a replacement CV boot is to ________.
“Burp the boot”
Lubricate the CV joint with chassis grease
Mark the location of the boot on the drive axle shaft
Separate the CV joint before installation

58. 5. A Cardan-type U-joint may require what tool(s) to replace?
CHAPTER QUIZ
5. A Cardan-type U-joint may require what tool(s) to replace?
A special tool
A torch
A press or a vise
May require any of the above

59. CHAPTER QUIZ
6. What needs to be removed to replace a drive axle shaft from a front-wheel-drive vehicle?
Tie rod end
Lower control arm or ball joint
Hub nut
All of the above

60. CHAPTER QUIZ
7. The splines of the driveshaft yoke should be lubricated to prevent ________.
A vibration
Spline bind
Rust
Transmission fluid leaking from the extension housing

61. CHAPTER QUIZ
8. It is recommended by many experts that an air impact wrench not be used to remove or install the drive axle shaft nut because the impacting force can damage the hub bearing.
True
False

62. CHAPTER QUIZ
9. Front and rear driveshaft U-joint working angles should be within ________ degrees of each other.
0.5
1.0
3.0
4.0

63. CHAPTER QUIZ
10. A defective (collapsed) engine mount on a front-wheel-drive vehicle can cause a vibration.
True
False