'ASE Automatic Transmission and Transaxle (A2) Practice Test 2025 – The All-in-One Resource for Mastering Your Exam!'

A vibration in a rear-wheel drive vehicle that correlates with vehicle speed is most likely caused by problems with driveshaft balance. The driveshaft transmits power from the transmission to the rear axle, and any imbalance within the driveshaft can lead to vibrations that become more pronounced as vehicle speed increases. This is due to the centrifugal forces acting on an imbalanced driveshaft; as the speed rises, the vibration intensity increases, often making it more noticeable at higher speeds.

When considering the other options, bad engine mounts would typically lead to vibrations that are felt more at idle or during engine acceleration, rather than being speed-dependent. Bad torque converter balance can cause issues, but it is generally more related to engine performance rather than a direct cause of a speed-related vibration felt in the chassis of the vehicle. Bad driveshaft angles can lead to driveline vibrations as well, but the primary issue concerning speed correlation is more directly associated with balance rather than angular misalignments.