Pickup Vibration and Clutch Judder After a Clutch Job
A rear-wheel-drive pickup has a vibration between 80 and 100 km/h that is worse under acceleration and almost disappears when the clutch is pressed and the vehicle coasts in neutral. The owner also reports a judder when pulling away, especially when the vehicle is hot. A clutch kit was fitted 5,000 km ago, but the flywheel was not replaced or machined. Propshaft runout measured at the centre is 0.60 mm against a 0.25 mm limit. The centre bearing rubber is split. There is light oil mist at the differential pinion seal. U-joints show no obvious play by hand, tyre pressures are correct, and wheel balance was done last week. The workshop has a dial indicator, vibration meter and a two-post hoist.
1. Separate the vibration from the judder. Which components are implicated, and which tests would you run first?
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The high-speed vibration is load-dependent and disappears when the clutch is pressed and the vehicle coasts in neutral. That points away from wheel balance, because wheel imbalance would remain while coasting, and away from the engine, because the symptom follows road speed rather than engine rpm. It points toward the propshaft, centre bearing, U-joints or differential pinion. The split centre bearing and 0.60 mm runout support that direction. The pinion seal oil mist may be a secondary effect of vibration or a separate leak.
The judder is a different symptom. It occurs at take-up, especially when hot, and follows a recent clutch job in which the flywheel was not machined or replaced. That implicates the clutch, flywheel or dual-mass flywheel, release mechanism, engine mounts or contamination. I would first inspect the propshaft and centre bearing, then check flywheel runout and clutch condition. I would not use one repair to try to cure both symptoms.
2. Interpret the runout and centre bearing findings. What repair sequence would you follow?
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A centre runout of 0.60 mm against a 0.25 mm limit is excessive. The split centre bearing rubber allows the shaft to whip and changes the driveline angle under load, which fits the acceleration-sensitive vibration. The U-joints may feel tight by hand and still be dry or binding under load, so I would check them through their full arc. I would also check pinion nut tightness, pinion bearing play and differential backlash before condemning the shaft alone.
The repair sequence is to remove the propshaft, mark its orientation, inspect the U-joints and splines, replace the centre bearing and any dry or notchy U-joint, and check shaft straightness. I would reinstall with the correct preload and phasing, then measure runout again. If runout remains above limit, the shaft needs replacement. I would then address the pinion seal and check differential oil level. A road test at the complaint speed and under load is the final check.
3. What would you check about the recent clutch job to prevent the judder from returning?
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I would check whether the flywheel was measured for runout and surface condition, not just wiped clean. A dual-mass flywheel with excessive rotational play or a warped solid flywheel can cause hot judder even with a new clutch. I would check the pressure plate bolts, clutch alignment, release bearing and pilot bearing. Oil or coolant contamination from a rear main seal or gearbox input seal can also cause judder.
I would verify that the correct clutch kit was fitted and that the bell housing and engine mounts are sound. If the flywheel was reused without machining, I would measure runout and inspect the friction face. The repair should include resurfacing or replacing the flywheel as specified, cleaning the splines and checking release geometry. Because the clutch job is only 5,000 km old, I would document the findings and discuss warranty with the customer before charging for a second repair.