You’ve just received your BIT or DOT inspection paperwork and recap from Managed Mobile’s recent visit.  One of the notes that grabs your attention states, “Driveshaft/Intermediate Shaft Out of Phase/Misaligned,” and you wonder to yourself, “what does that even mean? How does driveshaft phasing happen to my vehicle? What happens if I don’t repair it soon enough?”

A “driveshaft out of phase” problem would normally be noted during a bumper to bumper vehicle inspection such as a BIT or DOT inspection.  Driveshaft phasing is the process of aligning the driveshaft, U-joints, and slip yoke to balance and prevent unwanted vibration from the vehicle’s driveline system.  In some cases, there are two or even three shafts that need to be aligned properly to ensure that vibrations are not transmitted throughout the vehicle.

Now, you may look back in the vehicle’s repair history and not notice any repairs regarding the driveshaft or its removal.  In some cases, when a vehicle is towed, the driveline is removed to prevent damage to the unit’s powertrain, drivetrain (transmission) and differential during the tow.  After the vehicle is towed to its location the driveshaft needs to be reinstalled in the correct orientation to ensure the correct alignment and function of the drivetrain system.

The picture below illustrates the correct indexing of the driveshaft and U-Joints and shows what an incorrect or “out of phase” driveshaft would look like.

Seems simple, right?  It’s just a matter of rotating the driveshaft 90⁰ to line up the tube yoke with the slip yoke from the rear differential.  It’s such a small change in the orientation that you may not even notice a vibration inside the vehicle while its operating.  So why bother indexing the driveline when you don’t feel anything different while driving?

Although putting off those repairs can be convenient for the time being, these are the types of concerns that can turn into a much bigger problem down the road.  At Managed Mobile our focus is to ensure that these types of repair issues are brought to your attention and repaired in order to keep your fleet safe, compliant, and reliable.

As you can see in the pictures below the intermediate shaft is out of phase.  The intermediate shaft U-joints look to be slightly misaligned with each other.  This small misalignment can cause minor to major vibrations as the motor is propelling the vehicle via the driveshaft and intermediate shafts.

If the driveline is left out of phase even the small unfelt oscillations and unbalances will wear on the driveline components and eventually lead to failure.  U-joints, transmission output seals, and differential seals will all be placed under the stress of the driveshaft moving up and down.  On multi-piece driveshafts the center support bearing or bushing will also experience additional wear from the out of phase driveline causing failure of those components.

The stresses of a misaligned driveshaft on a vehicle can be easily remedied with a scheduled repair visit from Managed Mobile’s Repair team.  We will re-index and align your vehicle’s out of phase driveline at your location.  Aligning a driveline generally takes under an hour to complete.  This quick and simple repair can give you peace-of-mind that your vehicles are in top running order down to the smallest detail.

Who knew that such a small mis-alignment of the driveshaft could result in additional component stress and even failure?  Are your vehicle’s driveshafts properly indexed?