Five ASE A3 Manual Drive Train & Axles practice test questions, answers included.

1. Recall · Clutch Diagnosis and Repair

   On a car with a mechanical clutch linkage, the release bearing is found pressing on the pressure plate's release fingers with the pedal fully up, so the pedal has no free play. Which of these problems can this cause?

   1. Gear clash shifting into first at a stop
   2. Clutch slipping under heavy load
   3. A knock each time the pedal is pressed
   4. A spongy pedal near the floor
   Show the answer

   B. Correct. A bearing that keeps pushing on the fingers takes part of the diaphragm spring's force off the disc, so the clutch slips under load, and the bearing spins all the time and wears early. The linkage is adjusted to the manufacturer's free play specification.

   Why not the others

   A. Gear clash at a stop comes from a clutch that does not release fully, which follows too much free play or lost release travel. Taking away all free play does the opposite and gives the most release travel.

   C. A knock as the pedal is pressed points to the crankshaft moving forward against worn thrust surfaces when release force is applied. The linkage having no free play does not produce a knock.

   D. A spongy pedal comes from air in a hydraulic clutch. This linkage is mechanical, and with no free play the pedal meets firm resistance from the very top of its travel.

2. Recall · Transmission Diagnosis and Repair

   In a block-type synchronizer, what does the blocking (synchronizer) ring do as a shift is made?

   1. It locks the gear to the shaft and carries the torque
   2. It matches gear speed to sleeve speed by friction
   3. It holds the shift rail in place once in gear
   4. It keeps two shift rails from moving at once
   Show the answer

   B. Correct. As the sleeve moves, the ring's inner cone is pressed onto the gear's cone, and friction brings the gear to the sleeve's speed; until the speeds match, the ring's teeth stand in the sleeve's path and block it. Once the speeds are equal, the sleeve slides through the ring's teeth onto the gear's clutching teeth.

   Why not the others

   A. The sleeve, splined to the hub, locks the gear to the shaft once it slides onto the gear's clutching teeth, and the drive torque goes through the sleeve and hub. The blocking ring only matches speeds and blocks the sleeve until they match.

   C. Holding a rail in the selected position is the job of the detent ball and spring in the case or shift cover. The blocking ring matches gear speed to sleeve speed by cone friction before engagement.

   D. That is the interlock's job, done by pins or plates between the shift rails. The blocking ring matches gear speed to sleeve speed by cone friction and blocks the sleeve until they match.

3. Recall · Transaxle Diagnosis and Repair

   In each forward gear of a two-shaft manual transaxle, power passes from a gear on the input shaft directly to its mating gear on the output shaft. Compared with the input shaft, which way does the output shaft turn?

   1. The opposite way, in every forward gear
   2. The same way, in each of the forward gears
   3. The same way, but only in the top gear
   4. The opposite way, but only in reverse
   Show the answer

   A. Correct. Two external gears in mesh turn in opposite directions, so in each forward gear the output shaft turns opposite to the input shaft. The final drive mesh with the ring gear reverses it once more, so the wheels turn forward.

   Why not the others

   B. That would need a third gear between the pair or a direct coupling, and a two-shaft transaxle's forward gears have neither. Two meshing external gears turn opposite ways.

   C. A two-shaft transaxle has no direct-drive gear: its shafts are side by side, so even the top gear passes through one meshing pair and turns the output shaft the opposite way. Direct drive belongs to in-line rear-wheel-drive transmissions.

   D. In reverse the idler gear adds a third gear to the train, so the output shaft turns the same way as the input shaft and the car backs up. In the forward gears, one meshing pair turns it the opposite way.

4. Recall · Drive Axle Diagnosis and Repair

   Why does a rear axle with hypoid ring and pinion gears need a gear oil with extreme-pressure (EP) additives?

   1. Its differential clutch packs would chatter without them
   2. Its offset gear teeth slide hard across each other
   3. Its ring gear whips the oil into foam at speed
   4. Its pinion bearings need thin oil in cold weather
   Show the answer

   B. Correct. With the pinion offset from the ring gear's centerline, hypoid teeth slide across each other as well as roll, under very high contact pressure that can squeeze a plain oil film out. EP additives form a protective layer on the tooth surfaces that prevents scuffing and welding, which is why the axle gets the gear oil grade the manufacturer specifies.

   Why not the others

   A. Chatter in a clutch-type limited-slip unit is controlled by a friction modifier, a separate additive some manufacturers specify for those axles. EP additives are needed by any hypoid axle, open or limited-slip, because its teeth slide under heavy pressure.

   C. Gear oils do carry anti-foam additives, but that is a different additive with a different job. EP additives protect hypoid teeth where they slide across each other under heavy pressure.

   D. Cold-weather flow comes from the oil's viscosity grade, such as the multigrade the manufacturer specifies, not from EP additives. EP additives protect hypoid gear teeth that slide across each other under high load.

5. Recall · Four-Wheel Drive/All-Wheel Drive Component Diagnosis and Repair

   What makes a viscous coupling between a vehicle's front and rear drivelines transmit more torque?

   1. Silicone fluid sheared by a front-to-rear speed difference
   2. An electromagnet the module energizes to clamp its plates
   3. Hydraulic pressure from a pump the engine drives constantly
   4. Centrifugal weights that lock its plates above a set speed
   Show the answer

   A. Correct. A viscous coupling has interleaved plates splined alternately to its front and rear sides, sealed in a housing filled with silicone fluid. When one axle starts to slip, the two sets of plates turn at different speeds and the fluid's resistance to being sheared passes torque to the axle that still has grip; with no speed difference it passes almost none.

   Why not the others

   B. That describes an electronically controlled coupling, where a module sets the clamping force on a clutch pack. A viscous coupling has no electrical control; its torque comes only from silicone fluid sheared between plates turning at different speeds.

   C. A viscous coupling contains no pump and is not driven by the engine directly. Its torque comes from silicone fluid sheared between its plates when the front and rear sides turn at different speeds.

   D. There are no weights in a viscous coupling, and road speed alone does not engage it. Torque passes only when its front and rear plates turn at different speeds and shear the silicone fluid between them.

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