A3: Manual Transmission

A worn shifter bushing is the most likely cause of a loose or overly sloppy shifter in a manual transmission. This small rubber or plastic component sits between the shifter linkage and the transmission, helping to maintain a tight, precise connection. Over time, the bushing can degrade or break, leading to excessive play in the shifter and making gear changes less accurate. In some cases, it may even cause the transmission to slip out of gear.

While issues like a bent shift rail or shift rod linkage could also result in a loose shifter, these problems are less common and usually present additional symptoms—such as difficulty engaging specific gears or grinding during shifts.

A worn detent ball and spring may cause hard shifting into certain gears but is unlikely to be the primary cause of a loose-feeling shifter.

• Technician A is incorrect in recommending the replacement of the ring gear without also replacing the pinion gear. The ring and pinion gears are matched as a set to ensure proper contact and wear patterns. Replacing only one of these components can result in poor gear mesh, increased noise, and premature failure.

• Technician B is also incorrect in suggesting the use of a digital micrometer to measure ring gear runout. While a micrometer can accurately measure the diameter or thickness of a component, it is not suitable for checking runout. Runout refers to the amount of wobble or deviation as the ring gear rotates, which should be measured using a dial indicator for precise results.

• Therefore, neither technician is correct. If ring gear damage is suspected, both the ring and pinion gears should be inspected and replaced as a matched set if necessary, and proper diagnostic tools like a dial indicator should be used to measure runout. A qualified technician should handle the inspection and repair to ensure reliability and performance.

A stretched transfer case chain is the most likely cause of a popping sound when accelerating from a stop in 4WD. This chain connects the transfer case output shaft to the front or rear driveshaft and transmits torque to the drivetrain. Over time, the chain can wear or stretch, leading to slack. When torque suddenly increases—such as during acceleration from a stop in 4WD—the loose chain can slip or jump teeth, creating a noticeable popping or banging noise.

A faulty relay or shift motor, which controls engagement of the 4WD system, is unlikely to produce this kind of noise. Similarly, low engine vacuum may affect systems like power brakes but would not typically result in a popping sound in 4WD operation.

A binding universal joint can cause one-sided wear on the extension housing bushing. The universal joint, which allows the driveshaft to flex and change angles smoothly, consists of two yokes connected by four trunnions with needle bearings. When the trunnions cannot rotate freely due to binding, it creates uneven movement and side-loading on the driveshaft, leading to localized wear on one side of the extension housing bushing.

While excessive output shaft end-play can also contribute to bushing wear, it typically results in more uniform wear rather than wear concentrated on one side. Therefore, a binding universal joint is the more likely cause of one-sided bushing damage.

A vacuum-operated transfer case requires a minimum of 15 inches of mercury (inHg) of vacuum to activate the motor. Transfer cases can be controlled through various methods, including manual, hydraulic, or electronic systems.

Technician B is correct in stating that the vacuum motor operates a mode fork to shift between 2WD and 4WD. When sufficient vacuum is applied, the vacuum motor moves the mode fork, engaging or disengaging the transfer case to switch the drivetrain mode accordingly.

The photo shows a technician measuring backlash.

Backlash measurement is a crucial step when inspecting a rear axle, as it helps diagnose potential issues with the differential and gear alignment. Backlash refers to the slight clearance between the teeth of the ring gear and pinion gear when they are meshed. This gap ensures proper gear engagement and prevents excessive friction or noise during operation.

The limited slip clutch is the least likely cause of a vibration that increases with vehicle speed.

This clutch, located within the differential, helps distribute power evenly between the drive wheels. While a worn or faulty limited slip clutch can affect traction and handling, it typically does not produce speed-related vibrations.

In contrast, issues such as an unbalanced tire, worn U-joints, or excess undercoating on the driveshaft are common causes of vibration that worsens with speed. An unbalanced tire can cause the steering wheel to shake, while worn U-joints or driveshaft issues can create noticeable vibrations throughout the vehicle.

A clicking sound while cornering is a common sign of a worn or damaged constant velocity (CV) joint. CV joints allow the axle shaft to transfer power from the transmission to the wheels while accommodating suspension movement and steering angles. When a CV joint becomes worn or damaged, it can produce a clicking or popping noise during turns, especially under acceleration.

The torsional damper, on the other hand, is designed to reduce vibrations in the axle shaft and is not typically linked to clicking noises when turning.

Technician A is correct.
U-joints must be properly phased to prevent vibration. If they are out of phase, the driveshaft can vibrate excessively, potentially causing damage to the driveshaft, U-joints, and surrounding components.

Technician B is incorrect. While proper lubrication is important for the durability and smooth operation of U-joints, it does not address alignment issues. Greasing the joints will not eliminate vibrations caused by incorrect U-joint phasing. Proper alignment is essential for correct function.

If a clutch pressure plate is warped, resurfacing or machining will not correct the issue. Warping causes the plate to become uneven, leading to clutch engagement problems, slippage, and poor performance. In such cases, the only effective solution is to replace the pressure plate.

Although a pressure plate can sometimes be disassembled and resurfaced for minor surface imperfections, this process does not resolve warping. A warped pressure plate must be replaced to ensure proper clutch operation.

The shift linkage is a system of rods and cables that connects the gear shifter to the transmission, enabling smooth and precise gear changes. If the linkage is loose, worn, or improperly adjusted, it can lead to the transmission slipping out of gear.

Air in the hydraulic fluid can prevent the clutch from fully disengaging from the flywheel, leading to difficulty shifting and the vehicle creeping into gear. This happens because the air compresses within the hydraulic system, reducing the pressure needed to operate the clutch properly.

Similarly, excessive clutch pedal free travel can also cause incomplete disengagement of the clutch. When the clutch doesn’t fully release, it can result in slow or difficult shifting and may cause gear grinding when attempting to shift.

Both technicians are correct. The alignment tool is used to center and align the clutch friction disc during installation. The clutch pilot bearing—whether it’s a ball bearing, roller bearing, or brass bushing—supports and guides the transmission’s input shaft into the crankshaft flange. The alignment tool is designed to mimic the shape and size of the transmission’s input shaft to ensure proper positioning of the disc and pilot bearing.

The release bearing is the most likely cause of a chirping sound coming from the bellhousing when the clutch pedal is pressed.

This bearing, located inside the bellhousing, is responsible for disengaging the clutch when the pedal is depressed. Over time, it can wear out or become damaged, leading to a chirping or squealing noise during operation.

Although other components like a worn synchronizer assembly, clutch disc, or input shaft bearing can cause transmission noise, they are not typically located within the bellhousing and are less likely to produce a chirping sound specifically when the clutch pedal is engaged.

After a rear differential overhaul, setting the side bearing preload correctly is essential. This preload refers to the force applied to the bearings that support the differential assembly. If it’s not properly adjusted, it can lead to a whining noise as the differential rotates.

While the side gears and spider gears are internal parts of the differential, they are not typically adjusted or replaced during a standard overhaul. Although worn or damaged gears could cause noise, this is less common than issues related to incorrect bearing preload.

Therefore, if a whining sound is heard after reassembly, the side bearing preload should be checked first to ensure it has been set to the proper specification.

Shift forks are usually securely mounted to the shift rail and are designed to fit precisely into the synchronizer sleeve. Their primary function is to move the synchronizer sleeve back and forth along the transmission shaft, enabling gear engagement and disengagement. For smooth and accurate gear changes, the shift fork must be firmly attached to the shift rail. Additionally, the fork’s shape and dimensions must closely match the synchronizer sleeve to ensure proper alignment and reliable gear engagement.

A loose shift linkage can cause a manual transmission to pop out of gear during acceleration. When the linkage isn’t secure, it can allow unwanted movement of the shifter, leading to improper gear engagement or disengagement under load.

Similarly, worn motor mounts can also cause the transmission to shift out of gear. Excessive engine movement from damaged mounts can place strain on the transmission and shift linkage, disrupting gear alignment and causing the transmission to disengage during acceleration.

Technician A is correct in recommending the use of a dial indicator to measure flywheel runout. Flywheel runout refers to any side-to-side wobble or uneven rotation of the flywheel, which can lead to vibrations and clutch issues. A dial indicator is the standard tool for checking runout and determining whether the flywheel should be resurfaced or replaced.

Technician B is also correct in suggesting a dial indicator to measure crankshaft endplay. Endplay is the amount of axial (back-and-forth) movement of the crankshaft within the engine block. It is typically measured with a dial indicator mounted on a magnetic base or, in some cases, with a feeler gauge to ensure the movement falls within the manufacturer’s specified tolerance.

U-joints are a vital component of the vehicle’s drivetrain and should be replaced once they have failed. Reinstalling a repaired or used U-joint can leave it vulnerable to failure under load, potentially causing further damage to the drivetrain. Therefore, Technician B is correct in recommending the replacement of the faulty U-joint as the proper and reliable solution.

Technician A’s suggestion that a worn and loose drive chain could be the source of the noise is plausible. A stretched chain may slap against the inside of the transfer case, producing a noticeable sound. However, other potential causes should also be considered.

Technician B is also correct in stating that a faulty transfer case bearing could be responsible. A worn or damaged bearing can generate a loud noise as the transfer case operates, especially under load. Both possibilities warrant inspection during diagnosis.

If the bearing preload is correct in a shim-type differential but the backlash is excessive, the proper adjustment is to remove shims from the right side and add an equal amount to the left side. This shifts the differential assembly to the left, reducing backlash and improving the engagement between the ring and pinion gears.

The most likely cause of a difficult-to-shift five-speed manual transmission accompanied by gold-colored shavings in the transmission fluid is worn synchronizer blocking rings.

These gold-colored shavings indicate metal wear, typically from softer metals like brass or bronze—materials commonly used in synchronizer rings. As these rings wear down from repeated friction and pressure during gear changes, they lose their ability to properly match gear speeds, resulting in hard shifting and metal debris in the fluid.

While chipped gear teeth can also cause shifting issues and metal contamination, they usually produce larger, silver-colored fragments. The presence of fine, gold-colored shavings points more directly to synchronizer wear.

Loose shift rails may contribute to shifting problems but are unlikely to produce gold-colored debris. Likewise, casting slag is a manufacturing byproduct and is not typically associated with shifting difficulty or this type of metal wear.

Technician A is referring to the driveline angle—the angle between the transmission output shaft and the rear differential input shaft. An incorrect driveline angle can lead to vibrations at higher speeds. However, other factors like unbalanced tires or worn suspension components can also cause similar vibration issues.

Technician B points to a specific symptom: a squeaking noise when the vehicle is in reverse. This can indeed be caused by a worn cross shaft bearing surface in the rear U-joint. Still, other possible sources of squeaking noises include worn brake pads or a damaged wheel bearing.

The statement “the shaft closest to the seal area needs to be inspected and then repaired with sandpaper as needed” is incorrect. Sandpaper should not be used on the shaft near the seal, as it can leave scratches that may compromise the sealing surface and lead to leaks. The proper procedure is to clean the shaft with a suitable solvent and apply a light coat of grease to protect the seal and ensure proper sealing.

The other statements are accurate:

• Axle shaft seals should be replaced, not reused, as they can be easily damaged during removal or installation.

• A slide hammer is often required when removing certain types of axles, especially those that are stuck or tightly fitted.

• An axle shaft should not be stored or held upright, as doing so can cause the grease in the seal area to drain out, potentially leading to seal failure.

When removing the flywheel, it’s important to make index marks on both the flywheel and the crankshaft. These marks serve as reference points to ensure the flywheel is reinstalled in the same orientation. Proper alignment is critical for engine balance and smooth operation.

Technician B’s comment about removing too much material from the flywheel affecting the clutch release bearing is not relevant to the context of marking the flywheel. While excessive resurfacing can cause clutch-related issues, such as poor engagement or added stress on the release bearing, it does not pertain to the importance of indexing the flywheel prior to removal.

Chipped or rounded gear teeth can produce a growling or grinding noise, especially when the affected gear is engaged. While the noise may be present in all gears, it tends to be more noticeable in the selected gear due to the increased load it carries. Gear teeth are engineered to mesh smoothly, and any damage—such as chipping or rounding—disrupts this contact, leading to irregular engagement and resulting in noise during operation.

Technician A is correct: On front-wheel drive (FWD) vehicles, removing the drive shafts—commonly referred to as CV (constant velocity) axles—often requires a pry bar or a special puller. These axles can become stuck due to corrosion or wear, and specialized tools are typically needed to safely disengage them from the hub or transmission without causing damage.

Technician B is also correct: Axle nuts on FWD vehicles are generally considered non-reusable. These nuts are torque-to-yield fasteners, meaning they are stretched during installation to apply the correct preload on the wheel bearings. Reusing them can compromise that preload, increasing the risk of bearing failure. For this reason, manufacturers recommend replacing the axle nuts any time the axle assembly is serviced.

All of the above statements are correct. The image shows a hub and bearing assembly with an ABS tone ring attached. The hub uses a sealed bearing and plays a critical role in supporting the vehicle’s weight during acceleration, braking, and cornering.

In ABS-equipped systems, wheel speed is monitored by sensors that detect the passing teeth of the tone (or reluctor) ring. Many modern hub assemblies integrate the wheel speed sensor or tone ring directly into their design for more accurate ABS function and improved durability.

The input shaft bearing supports the input shaft, which links the clutch to the transmission. When this bearing becomes worn or damaged, it can cause the input shaft to wobble, often resulting in a grinding noise, particularly at the front of the transmission.

While other components—such as the clutch release bearing, output shaft bearing, or pilot bearing—can also create noise in a manual transmission, they are less likely to produce a grinding sound in this specific location. To ensure accurate diagnosis and proper repair, it’s recommended to have a qualified mechanic inspect the transmission and identify the exact source of the noise.

The micrometer shown above is an inch-based model, with graduations in thousandths of an inch. The measurement displayed is 0.228″.

A damaged transmission case can result in an oil leak and may also indicate potential damage to the rear extension housing mating surface or center adapter plate. Cracks or other damage to the transmission case can allow fluid to escape, leading to low transmission fluid levels and possible harm to internal components.

Moreover, damage to the case can place extra stress on the rear extension housing or center adapter plate, increasing the risk of failure in those areas. Other unrelated issues are unlikely to occur as a direct result of these specific component failures.

A growling noise from the rear of a rear-wheel-drive vehicle during cornering is most commonly a sign of a worn or failing rear axle bearing. These bearings support the vehicle’s weight and enable smooth wheel rotation. When they become worn or damaged, they can produce a growling or rumbling sound, especially noticeable while turning due to the added lateral load.

Although incorrect drive pinion bearing preload can cause noise in the differential, it is less likely to produce a growling sound specifically during cornering.

The term “toe contact” describes a condition where the contact between the ring gear and pinion teeth is concentrated near the toe, or inner edge, of the gear teeth. This typically results from insufficient backlash—the small amount of clearance between the ring gear and pinion.

When toe contact occurs, the contact pattern appears primarily at the inner edges of the teeth on both the drive (convex) and coast (concave) sides. This uneven contact is caused by improper alignment due to the reduced backlash, preventing the load from being evenly distributed across the entire tooth surface.

Wheel bearings enable the wheels to rotate smoothly while supporting the vehicle’s weight. When a wheel bearing becomes worn or damaged, it can create a growling or grinding noise, particularly noticeable when the vehicle turns. In this scenario, turning left shifts the vehicle’s weight to the right front wheel, putting additional load on the faulty bearing and making the noise more pronounced.

Technician A is correct in stating that a faulty shift motor could cause this issue. The shift motor controls the engagement of the transfer case, moving it into the selected drive mode. If the motor is malfunctioning, it may fail to position the transfer case correctly, leading to a failed shift and a flashing indicator light.

Technician B is also correct that a bent actuator shift fork could be the cause. The shift fork moves the shift collar to engage the desired gear. If it is bent or damaged, it may prevent proper gear engagement, resulting in a failed shift and a flashing indicator light.

Therefore, both technicians present valid potential causes of the problem.

A faulty pilot bearing is the most likely source of a squealing noise coming from the clutch housing when the clutch pedal is pressed. This small bearing, located between the engine crankshaft and the transmission input shaft, allows the input shaft to rotate smoothly when the engine is running but the clutch is disengaged. If the pilot bearing is worn or damaged, it

A weak detent spring is the most likely cause of a manual transmission slipping out of third gear. The detent spring is a spring-loaded mechanism inside the transmission that helps hold the shift lever securely in gear. When the spring becomes weak or worn, it may fail to maintain proper gear engagement, allowing the transmission to pop out of gear—an issue commonly seen in older manual transmissions.

While worn bushings or a worn shifter bushing can cause a loose or imprecise feel when shifting, they are less likely to cause the transmission to actually slip out of gear. Similarly, high fluid pressure is not a typical cause of this problem; it may contribute to other issues such as harsh or noisy shifting but does not directly affect gear retention.

Based on the symptoms described—a hard, binding clutch pedal and the clutch sticking or failing to fully disengage—the most likely cause is a faulty clutch release bearing.

The clutch release bearing disengages the clutch when the pedal is pressed. If it becomes worn or damaged, it can prevent the clutch from releasing completely, making it difficult to shift gears. It can also create resistance in the pedal, causing it to feel stiff or binding.

While issues with the input shaft or input shaft bearing might produce some similar symptoms, they are less common and typically result in different signs, such as grinding or whining noises. The vacuum booster, which assists brake pedal effort, does not play a role in clutch operation and is unlikely to be related to this issue.

Both technicians are correct. A worn outboard CV joint usually produces the most noise while turning, as it transmits power to the wheels at sharp angles during cornering. In contrast, a faulty inboard CV joint typically makes noise during acceleration or deceleration, since it handles power transfer while the suspension moves in and out under load. Each joint plays a different role depending on driving conditions, which is why their symptoms appear at different times.

The viscous coupling is exclusive to AWD models. All other components are found on both FWD and AWD configurations.

The flywheel is bolted to the pressure plate, but it’s important to clarify that the component shown in the image is a clutch disc, not a pressure plate.

When the diaphragm spring fingers are depressed, they release the pressure plate’s clamping force, allowing the clutch disc to rotate freely. The clutch disc contains the friction material and is positioned between the flywheel and the pressure plate. It is splined to the transmission’s input shaft, enabling it to transmit engine power to the drivetrain.

The pressure plate, which is bolted to the flywheel, applies pressure to the clutch disc to engage the drivetrain. While it may help dampen some vibrations, its primary role is to maintain consistent contact between the flywheel and clutch disc, not to reduce engine vibration.

Difficulty shifting into first gear is often a sign of a clutch system issue. The clutch’s primary function is to disengage engine power from the transmission, allowing for smooth gear engagement. If the clutch is out of adjustment or not fully disengaging, it can make shifting into first gear—and sometimes other gears—difficult or even impossible.

Technician A’s claim that the first speed blocking ring is the likely cause is not accurate in this scenario. While the blocking ring helps synchronize gear engagement in manual transmissions, it typically affects more than just first gear when faulty. If the problem is isolated to first gear, a clutch disengagement issue is a more probable cause than a worn blocking ring.

Both Technician A and Technician B could be correct, as both a leaking wheel cylinder and a leaking axle seal can lead to fluid contamination on the backing plate and brake shoes.

The wheel cylinder, a key component in drum brake systems, applies hydraulic pressure to the brake shoes. If it leaks, brake fluid can seep out and coat nearby parts, including the backing plate and brake shoes, reducing braking performance.

Similarly, the axle seal—located at the end of the axle shaft—prevents differential fluid from leaking onto the brakes. When it fails, gear oil can escape and contaminate the same components, leading to similar symptoms. Therefore, both sources of leakage should be inspected when fluid contamination is found in the brake assembly

Defective needle bearings in the countershaft gear assembly can definitely cause binding and make the transmission difficult to rotate. These bearings support the countershaft, which transfers power from the input shaft to the output shaft. When needle bearings become worn or damaged, they can restrict the countershaft’s movement, leading to binding.

Worn tapered roller bearings can also contribute to binding in a manual transmission. These bearings are commonly used to support shafts and gears, and if they wear out, they can lead to misalignment or excessive friction, making it hard to rotate the transmission components smoothly.

Vibration is a common issue associated with conventional Cardan U-joints, which are used to drive the front wheels. Technician A is incorrect in stating that a rear driveshaft imbalance causes an out-of-balance driveshaft. In reality, an imbalanced rear driveshaft results in constant vibration, regardless of speed or load, rather than causing the driveshaft itself to become out of balance.

It’s important to emphasize that removing the snap ring and input shaft bearing should be performed only by someone with the appropriate tools and experience, as improper handling can lead to damage or injury.

Common signs of a failing CV joint include a clunking noise during acceleration from a stop, popping or clicking sounds when turning, and vibrations at specific speeds. These symptoms typically point to worn or damaged CV joints that may require replacement. However, a whining noise while slowing down is more often related to problems with the brakes or wheel bearings, rather than the CV joint.

The statement “The meter should display continuity 0.00 with the pedal out and the switch contacts open” is incorrect regarding the clutch safety switch. When the clutch pedal is out (not depressed), the switch contacts should be closed, allowing continuity through the circuit. When the pedal is depressed, the contacts should open, breaking the circuit. Therefore, the meter should show continuity when the pedal is out, and no continuity when the pedal is pressed.

The other statements are accurate. The clutch safety switch is part of the starting system and prevents the engine from starting unless the clutch pedal is depressed. A multimeter is a suitable tool for diagnosing and testing the clutch safety switch circuit.

Technician A’s recommendation to measure the clearance between the shift fork and the synchronizer sleeve using a feeler gauge is a sound diagnostic step. The synchronizer assembly ensures that the gear and input shaft are rotating at compatible speeds before engagement, reducing wear and preventing gear grinding. Incorrect clearance between the shift fork and synchronizer sleeve can lead to hard shifting or grinding during gear changes.

Technician B is also correct in suggesting that a bent shift rail could contribute to hard shifting. The shift rail guides the movement of the shift forks to engage specific gears. If it’s bent or damaged, it can hinder smooth fork movement, resulting in shifting difficulties or gear engagement issues.

Measuring backlash in a rear axle is a critical step in diagnosing and troubleshooting potential problems with the differential and gearset. Backlash refers to the small gap or clearance between the meshing teeth of the ring gear and pinion gear. This spacing allows for proper gear engagement and smooth operation within the differential.