I. Observation of Fault Symptoms

1.A knocking noise occurs from the integrated drive shaft during vehicle start-up or gear shifting, especially when driving at low speed in high gear.
2.No abnormal noise during start-up, but knocking noise appears while the vehicle is moving.
3.No abnormal noise during start-up, but noise occurs when the vehicle is coasting.
4.Continuous noise is present throughout the entire driving process.

II. Analysis of Fault Causes

1.Loose flange connections (or connecting bolts) of the integrated drive shaft cause abnormal noise.
2.Blocked grease passages in grease fittings and universal joint cross shafts, lack of lubrication, infrequent greasing, or damaged cross shaft oil seals lead to long-term oil starvation of needle bearings. This results in excessive wear of cross shaft journals, needles and sleeves, causing looseness and noise.
3.Excessive tightness of the universal joint cross assembly.
4.Loose fit between the sleeve and yoke bore, or loose support plate bolts, causing sleeve rotation, excessive wear of the yoke bore, and resulting noise.
5.Excessive wear of the transmission second shaft splines and internal splines of the flange, leading to looseness and noise.
6.Loose mounting bolts of the integrated drive shaft center support; loose fit between the center support and the shaft journal; loose fit between the rear spline and the flange keyway; loose rear lock nut.
7.Damaged or collapsed center support bearing, worn bearing raceways, poor lubrication, or excessive bearing wear and looseness.
8.Misaligned installation of the center support bracket, improper bearing preload adjustment, damaged rubber cushion gaskets, or incorrect tightening torque of bracket bolts leading to bracket displacement.
9.Universal joint yokes at both ends not lying in the same plane, destroying the constant‑velocity arrangement and causing noise.

III. Fault Troubleshooting

1.A metallic knocking sound during sudden speed changes indicates excessive wear or looseness in individual flanges or universal joint cross bearings.
2.A “clunk” noise at start-up, or intermittent “grating” sound during reverse on a gentle slope, may indicate broken needles; the needle bearing should be replaced.
3.Obvious metallic knocking during start-up or shifting (more noticeable in low gear) is mostly caused by loose fit between the center support inner ring and the shaft.
4.Persistent loud “clattering” noise accompanied by vibration during start-up or operation usually indicates loose center support mounting bolts.
5.Clear, rhythmic metallic knocking at low speed, which becomes distinct when coasting, is mostly due to excessive preload on universal joint bearings, resulting in stiff rotation.
6.Increasing noise with vehicle speed, accompanied by dull, continuous humming from the center support bearing, indicates excessive wear or failure of the center support bearing.