NCED Transmission & Drivetrain Systems 5

Question 1

Which symptom most specifically indicates a worn or failing torque converter clutch (TCC) solenoid?

Accepted Answer

Shudder at light throttle around 40-50 mph during TCC lockup

Answer

A faulty TCC solenoid causes the lockup clutch to apply or release erratically, creating a characteristic shudder felt at light throttle near the lockup engagement speed.

Question 2

In a 4WD system using manual locking hubs, what is the purpose of the locking hub?

Accepted Answer

It mechanically connects the front wheel to the front axle shaft to allow 4WD power transfer

Answer

When locked, the hub couples the wheel to the axle shaft so torque from the transfer case can drive the front wheels; when unlocked, the axle shaft spins freely to reduce parasitic drag.

Question 3

Which gear in a final drive assembly is responsible for transmitting torque at 90 degrees from the driveshaft to the axle shafts?

Accepted Answer

Hypoid ring and pinion gear set

Answer

The hypoid ring and pinion redirects driveshaft torque 90 degrees to the axle shafts while also providing a final gear reduction ratio.

Question 4

What is the primary reason automatic transmission fluid (ATF) specifications (e.g., Dexron, Mercon, SP-IV) must be matched to the transmission?

Accepted Answer

Each ATF formulation has specific friction modifiers that calibrate clutch engagement feel and shift quality

Answer

Friction modifiers in ATF are engineered to match the clutch materials in a specific transmission; using the wrong fluid alters shift feel and can cause shudder, slipping, or damage.

Question 5

A rear-wheel drive vehicle with a worn carrier bearing (center support bearing) on a two-piece driveshaft will most likely exhibit:

Accepted Answer

A droning or vibration that changes with vehicle speed and may worsen under load

Answer

A failing center support bearing allows the driveshaft to wobble and vibrate at speeds proportional to shaft rotation, often worsening under load or torque.

(NCED) Nationally Certified Educational Diagnostician Practice Test

(NCED) Nationally Certified Educational Diagnostician Practice Test

NCED Transmission & Drivetrain Systems 5