The most memorable “can’t be fixed” vehicle I have ever diagnosed was a full-sized Chevrolet SUV.

This vehicle had been sold new by a local dealership; it had a vibration problem. The service department tried several things to fix the vibration but could not. The dealership repurchased the vehicle and ended up selling it again. The new owner brought the vehicle back to have the vibration repaired. Again, the service department tried several things to fix the vibration but could not fix it. The dealership repurchased the vehicle for a second time, and then I received a phone call from the service manager asking for help.

While listening to the service manager describe the history of this vehicle, I learned that in an attempt to repair the vibration, the dealership service department had replaced the following parts on the vehicle:

  • Tires
  • Wheels
  • Rear Axle
  • Rear driveshaft
  • Rear driveshaft again
  • Transfer case
  • Transmission
  • Engine
  • Front axle
  • Front driveshaft

They had balanced the tires several times and had the new driveshafts balanced; nothing would fix this vibration. The vehicle must be a Lemon; it can’t be fixed.

Using the same diagnostic procedure outlined in our new NVH smartphone app, a few students and I performed a quick road test. The road test results indicated that the vehicle had a second-order driveshaft speed-related vibration. As the NVH app’s diagnostic help file indicates, second-order driveshaft speed-related vibrations are only caused by a few select problems on the vehicle.

  • Cross-Type Universal Joints with excessive radial or axial play
  • Driveshaft end yokes being out of phase
  • Excessive Cross-Type Universal Joint working angles
  • Unequal Cross-Type Universal Joint working angles

While my students and I were working our way down this list of items to check, we discovered that the working angles of the universal joints of the rear driveshaft were unequal and beyond specifications for that vehicle. We performed some calculations and discovered that if we lift the transmission/transfer case mount a little higher above the cross member, the universal joint working angles will become closer to equal. We installed a 1/8 inch thick shim under the transmission mount and road-tested the vehicle again. The vibration problem was fixed.

There were no bad parts on this vehicle. Two very unhappy customers were the result. Thousands of dollars were wasted on parts, and many hours of labor were wasted because nobody knew how to diagnose a vibration problem; they were guessing! The NVH app eliminates the guesswork in vibration diagnosis and guides you step-by-step through the entire diagnostic and repair procedure. Get the NVH app today by clicking on the link below.

What the app can do

The NVH app is designed to automatically detect the type of vibration your vehicle is experiencing, provided the instructions of the road test procedure are followed.

There are 14 types of vibrations the NVH app can automatically detect:

  • Tire speed-related (1st, 2nd, and 3rd order vibrations)
  • Driveshaft speed-related (1st, 2nd, and 3rd order vibrations)
  • Engine speed-related (0.5, 1st, 2nd, 3rd, 4th, 5th, and 6th order vibrations)
  • Electric Motor Speed Related (1st order vibrations)

Each type of vibration has unique causes. A vibration type is not the same thing as a vibration source. There are many possible causes (sources) for each vibration type. The NVH app includes step-by-step instructions on locating the vibration source once the app has identified the type of vibration.

What the app cannot do

  •  The NVH App cannot automatically tell you the source of a vibration
  • Although the NVH app is excellent at identifying the type of vibration your vehicle is experiencing, you or someone else will need to follow the diagnostic steps described in the app help files to identify the exact cause or source of the vibration.

There are almost 300 possible sources of vibration concerns in today’s vehicles

T1 Diagnostic Help


Turn your Phone or Tablet into a Vibration diagnostic tool! Purchase our new App to use the internal sensors of your Phone or Tablet to diagnose the type of vibration your car or truck is experiencing. There are close to 300 individual vibration sources on a typical vehicle; the NVH App knows each one of them and can guide you through the entire diagnostic and repair procedures for each one of them.

What issues have you had with diagnosing vibration, harshness and noise issues?

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