Further Discussion

Poor driveline modifications have been occurring for many years. These modifications often set up powerful vibration resonances in the driveline that pound and bend the critical links surrounding the shafts - joints, transmissions and axles. Frequent joint replacements, cracked manual transmission housings, and needless front wheel alignments and balances, are often attributable to poor driveline modifications. The C6 automatic transmission appeared relatively indifferent. However, the introduction of the E40D transmission brought components internal to the transmission that are sensitive to these vibrations. Also, higher driveshaft operating speeds from the overdrive feature now make driveline specifications more critical. Therefore, adherence to the guidelines in this bulletin is necessary to maintain the reliability of current generation drivetrains.