Five free practice questions on drive shafts, half-shafts and CV joints: content area D of the ASE A3 Manual Drive Train & Axles test, 5 of its 40 scored questions (12.5%). They are in the ASE format: four options, one best answer. Answer each one before opening the explanation. No account, no email.
01The questions
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A rear-wheel-drive pickup's one-piece drive shaft has a single U-joint at each end, and its rear axle is held to leaf springs by U-bolts, with no control arms. The rear U-joint's working angle must be changed by tilting the axle pinion. How is this done?
- With shims at the transmission mount
- With shims under the center support
- With pinion depth shims in the carrier
- With a tapered shim at the spring seat
Show the answer
D. Correct. A tapered (wedge) shim between the leaf spring and the axle's spring seat rotates the axle housing, tilting the pinion up or down to change the rear working angle. The U-bolts are then torqued to specification and the angles rechecked at the manufacturer's specified ride height.
Why not the others
A. Shims at the transmission mount tilt the transmission and change the front joint's working angle; they do not tilt the axle pinion. On a leaf-spring axle the pinion angle is changed with a tapered shim at the spring seat.
B. A one-piece shaft has no center support; shims there set the angles of a two-piece shaft at its center bearing. On this leaf-spring axle the pinion is tilted with a tapered shim at the spring seat.
C. Pinion depth shims move the pinion gear toward or away from the ring gear to set tooth contact; they do not tilt the axle housing or change the pinion's angle to the drive shaft. On this axle a tapered shim at the spring seat does that.
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A drive shaft's original U-joints have no snap rings: their bearing caps are held by nylon injected into the yoke at the factory, and pressing the caps out shears it. The manufacturer replaces them with a service-kit joint held by snap rings. What does its procedure call for before the new joint is pressed in?
- Fitting the original caps to the new cross
- Leaving the sheared nylon to keep the caps snug
- Cleaning the sheared nylon out of each cap bore
- Injecting fresh nylon through the yoke's fill holes
Show the answer
C. Correct. Pressing the old caps out shears the injected nylon, and pieces left in the bores or the snap-ring area keep the new caps from going in squarely and the snap rings from seating. With the bores clean, each cap is pressed in just far enough to fit its snap ring and the joint is checked for free movement.
Why not the others
A. The original caps were held by nylon and have no snap-ring grooves, so the kit's snap rings could not retain them, and their needles have worn against the old trunnions. The kit's own caps are used, once the sheared nylon is cleaned out of each bore.
B. Nylon left in a bore keeps the new cap from sliding in squarely and can stop its snap ring from seating, so the cap may bind or work loose. The kit's snap rings do the retaining; the sheared nylon is cleaned out of each bore first.
D. Injected nylon is how the joint was retained when the shaft was built; a service joint is held by the snap rings that come in its kit. The old nylon is cleaned out of each bore so the new caps and rings seat.
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A rear-wheel-drive pickup's drive shaft is being checked for runout on the vehicle with a dial indicator. Any of these could make a reading exceed the manufacturer's limit EXCEPT:
- a tube bent by striking a road hazard.
- worn U-joints that let the shaft's ends shift.
- a balance weight knocked off the tube.
- a dent in the tube under the indicator tip.
Show the answer
C. Correct. Runout measures how far the tube's surface moves off center as it turns, and a balance weight is a small mass welded to the tube; losing one throws the shaft out of balance but does not move the tube off center. A missing weight is found by looking and is corrected by rebalancing the shaft.
Why not the others
A. This could do it: a bend moves part of the tube off the shaft's center line, so the indicator swings as the shaft turns. The exception is the lost balance weight, which changes the shaft's balance but not its shape.
B. This could do it: a worn joint lets that end of the shaft move as it is turned, so the indicator reads movement that is not in the tube itself; the joints are checked for play before runout is read. The exception is the lost balance weight.
D. This could do it: the tip drops into the dent each turn and adds its depth to the reading, which is why readings are taken on smooth, clean tube metal. The exception is the lost balance weight.
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A bolt-on front hub-and-bearing assembly is being replaced on a front-wheel-drive car, with the half-shaft's outer joint slid out of the hub and its inner joint still in the transaxle. Each of these is correct practice EXCEPT:
- cleaning rust and scale off the knuckle's mounting face.
- torquing the hub mounting bolts to specification.
- letting the half-shaft hang from its inner joint.
- fitting a new axle nut where the manufacturer calls for one.
Show the answer
C. Correct. Left hanging, the half-shaft bends the inner joint past its normal angle and can over-extend it, damaging the boot or pulling the joint apart, so it is supported with wire or a strap near its installed position. Cleaning the mounting face, torquing the bolts and fitting a new nut where required are all part of the job.
Why not the others
A. This is correct: rust or scale left under the new hub's flange tilts it, which can change camber and load the bearing unevenly. The exception is letting the half-shaft hang from its inner joint.
B. This is correct: the bolts clamp the hub to the knuckle and must hold their specified torque. The exception is letting the half-shaft hang from its inner joint, which can damage the joint or its boot.
D. This is correct: many axle nuts are staked or have a prevailing-torque feature and are made for one use, and the manufacturer says when a new one is required. The exception is letting the half-shaft hang.
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A long-wheelbase pickup uses a two-piece drive shaft with a center support bearing instead of one long tube of the same diameter. Which of these is the main reason?
- Each short section stays below its critical speed
- It lets the drive shaft change length as the axle moves
- It cancels the U-joints' speed variation
- It lets each U-joint run at a zero working angle
Show the answer
A. Correct. A long, slender tube whips (bows outward) once it reaches its critical speed, and the longer the tube, the lower that speed; splitting the span with a center support keeps each section well below its critical speed at highway speeds. A larger or stiffer tube is the other way to raise it.
Why not the others
B. A slip yoke or slip spline takes the length change, and a one-piece shaft has one too. The reason for splitting the shaft is critical speed: a shorter section can turn faster before it whips.
C. Speed variation is canceled by equal, in-phase joint angles; a two-piece shaft adds a third joint whose angle must also be managed. The split keeps each section below its critical speed.
D. The joints of a two-piece shaft still run at working angles, set at the center support. The center support exists because a shorter section has a higher critical speed than one long tube.
02Answer key
| Question | Answer |
|---|---|
| Q1 | D |
| Q2 | C |
| Q3 | C |
| Q4 | C |
| Q5 | A |
03What area D covers
This content area covers the shafts that carry power from the transmission or transaxle to the wheels on front- and rear-wheel-drive vehicles. Questions deal with U-joints and CV joints, boots, slip yokes and flexible discs, center support bearings, drive shaft balance and runout, working angles and phasing, and the wheel bearings, hubs and seals the shafts drive through.
The ASE test specification calls this content area “Drive Shaft/Half-Shaft and Universal Joint/Constant Velocity (CV) Joint Diagnosis and Repair (Front and Rear Wheel Drive)”. It carries 5 of the 40 scored questions, 12.5% of the test.
- Diagnose drive shaft and CV joint noise and vibration
- Replace U-joints, CV joints, boots and flex discs
- Service center support and intermediate shaft bearings
- Check drive shaft balance and runout
- Measure and correct U-joint working angles
- Replace wheel bearings, hubs and seals
04What the questions turn on
Clicking in tight turns
The outer CV joint runs at its largest angle when the front wheels are steered sharply, so worn races or cage windows let its balls click there as they load and unload. Rapid clicking in tight turns points to that side's outer joint.
Working angle is a difference
A single U-joint at an angle makes its output speed up and slow down twice a turn. Its working angle is the difference between the slopes of the two shafts it joins, checked against the limit and against the other joint's angle.
Runout is not balance
Runout is the total indicator movement in one turn, the highest reading minus the lowest, taken on clean tube metal away from the welds. A missing balance weight upsets balance without moving the tube off center, so it is fixed by rebalancing.
Hold the yoke, not the tube
A drive shaft tube is thin-walled, so only the yoke goes in the vise when U-joint caps are pressed, with the tube supported on a stand. Vise jaws on the tube can dent or distort it and add runout and imbalance.
05The other content areas
The A3 test has six content areas. Each has its own page of free questions:
The ASE A3 Manual Drive Train & Axles practice test page describes the full question bank. How these questions are written and checked: how our questions are made. Found a mistake? Tell us and we will fix it.
ToolboxPrep is an independent study site. It is not affiliated with or endorsed by ASE (the National Institute for Automotive Service Excellence). Our questions are original practice questions written to the published ASE test specifications; they are not actual test questions.