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Diagnosing Driveline Vibration

Wheel torque specs

Seemingly random vibrations in your car can be very tough to diagnose. If you've ruled out the basics such as tire balance, brake issues, transmission, and so on, it's time to look at the driveline.

In a front-wheel drive or all-wheel drive vehicle, you'll typically have two axles with CV joints on the shaft. Inner CV joints are common vibration causers, especially when the vehicle is at highway speeds. The easiest way to diagnose this is to get the vehicle up to speed (60-70 mph) and turn (change lanes, for example). If the vibration gets worse in turning one way or the other (or both), it's likely a CV problem.

If it is a CV joint, figuring out which side is not easy and is mostly just guessing. Axles with CV joints intact are generally cheaper and easier than attempting to replace an inner CV. Start by lifting the vehicle and pressing on the inner CV on each side. The one that has more play is likely the broken one, but that's not always the case and you may end up replacing both to fix your problem.

In all-wheel drive and rear-wheel drive vehicles, if the vibration is in the longer driveshaft running to the rear differential, you will more likely feel the vibration at middle and higher speeds and it will probably be decidedly towards the rear of the car. Diagnosis is mostly a matter of observation. A bad rear driveshaft will usually show signs of wear or imbalance when looked at from the floor (underneath the car).

The problem may be bad mounts, a bad shaft, or bad connections on the shaft.