This Preliminary Information communication provides information to the technician on the steps to diagnose and repair vehicles that have a resonance type vibration occurs between 40 to 60 MPH. In most cases the engine must be under a slight load such as Air Conditioning compressor engagement, light throttle, and in 6th gear Torque Converter Clutch applied. Technician will relax the engine and transmission mounts, then the exhaust system by loosening the front pipe studs. Also work down the system disconnecting one exhaust hanger at a time. Then take the vehicle on a test drive to verify there was improvement. If additional steps are required place two sets of exhaust dampeners one set before and one set after the front catalytic converter. It may be required to move the pair of dampeners along the exhaust system to get the best results.
