ASE A3 Manual Drive Train and Axles
11. A manual transmission makes a grinding sound at the front of the transmission with the engine running and the clutch fully engaged. Which of the following is causing this noise?
- A. A faulty input shaft bearing.
- B. A faulty output shaft bearing.
- C. A faulty clutch release bearing.
- D. A faulty pilot bearing.
Answer A is correct. A faulty front or input shaft bearing is loudest when the clutch is fully engaged, and the input shaft is spinning at engine speeds.
Answer B is wrong. A faulty output shaft bearing makes a grinding or growling noise toward the back of the transmission.
Answer C is wrong. The clutch release or throwout bearing depresses the pressure plate fingers, releasing the clutch. When faulty or worn, it makes a squealing or growling noise when the clutch pedal is depressed, and the clutch is disengaged.
Answer D is wrong. A faulty pilot bearing is loudest when the clutch pedal is completely depressed, and the clutch is fully disengaged. The input shaft has slowed while the crankshaft is still spinning at engine speed.
12. Which of the following are placed at the ends of the transmission shafts and require a slight preload?
- A. Sealed ball bearings.
- B. Thrust bearings.
- C. Tapered roller bearings.
- D. Needle bearings.
Answer A is wrong. Ball bearings consist of small steel balls, separated from each other by a steel cage. They're capable of withstanding both radial and axial loads.
Answer B is wrong. Thrust washers adjust and control shaft end play. Use selective washers and a dial gauge placed against the end of a shaft or gear to adjust end play.
Answer C is correct. Tapered roller bearings are used in differentials, final drives, and transfer shafts and require a slight preload. Always check with the vehicle manufacturer's specifications before setting preload on a tapered roller bearing.
Answer D is wrong. Needle bearings or Torrington bearings consist of small needle-like bearings. These small bearings are held in a round cylinder by assembly grease.
13. A 4WD vehicle makes a popping sound when accelerating from a stop. This sound only occurs in 4WD. Which of the following is causing this condition?
- A. Low engine vacuum.
- B. A faulty shift motor.
- C. A stretched transfer case chain.
- D. A faulty relay.
Answer A is wrong. Some transfer cases are controlled by vacuum. Make sure the case receives the specified engine vacuum to ensure proper shifting. Low engine vacuum does not cause a popping sound in 4WD.
Answer B is wrong. The module controls a motor that moves a set of rails and forks. A faulty shift motor prevents 4WD engagement.
Answer C is correct. If the transfer case makes a popping sound when placed into 4WD, it's excess slack in the chain striking the case and then snapping back into position.
Answer D is wrong. Circuit problems like a faulty relay typically prevent motor operation.
14. A vehicle has an excessive vibration at highway speeds. Technician A says to use a dial gauge to measure the driveshaft for driveshaft runout. Technician B says to test the driveshaft companion flange for runout by placing a dial gauge on the flange surface and rotating the flange. Who is correct?
- A. Technician A
- B. Technician B
- C. Both A and B
- D. Neither A or B
Answer A is wrong. Both technicians are correct. To check the driveshaft for excessive runout, shut down the engine and make sure the shaft is not rotating. Place a dial gauge at the center and both ends of the driveshaft and turn it with your hand. Compare the measurements taken with the manufacturer's specifications before considering replacement.
Answer B is wrong. Check the flange for runout by placing a dial gauge on the flange surface and rotating the flange. Little tolerance is allowed, check for specifications before proceeding.
Answer C is correct. Both technicians are correct.
Answer D is wrong. Check the driveshaft for undercoating; undercoating on a driveshaft results in a driveline vibration.
15. The measurement taken in the illustration above is checking for:
- A. Ring gear runout.
- B. Pinion bearing preload.
- C. Ring gear backlash.
- D. Ring gear tooth contact pattern.
Answer A is wrong. To measure ring gear runout, place the tip of the dial indicator on the back of the ring gear. If out of specifications, check the ring gear's mounting.
Answer B is wrong. Pinion bearing preload is the tension placed on the pinion gear's tapered bearings.
Answer C is correct. Use a dial indicator to check ring gear backlash in a differential's ring and pinion gear set. It's measured and adjusted after the pinion gear is installed and adjusted.
Answer D is wrong. Apply tooth contact compound to the ring gear in two different places and rotate the gear to retrieve the ring gear's tooth contact pattern. The pattern should be centered between the top and the bottom of the gear's teeth.