Rear Axle - Radial Play in Right Side Axle Flange

GROUP 33
Rear Axle

33 01 01

Woodcliff Lake, NJ
June 2001
Service Engineering

SUBJECT
Radial Play in Right Side Rear Axle Output Flange

MODEL
E46 M3 with S54 engine

SITUATION
Field reports have indicated that when diagnosing a drivetrain rattle or knocking noise during a load change, i.e. 1st to 2nd gear shift at low engine speed, a noise appears to be coming from the rear axle area.

Further drivetrain checks reveal that the right side rear axle output flange appears to have "excessive" or more play (approximately 0.5 mm to almost 1 mm) when compared to the left side output flange.

INFORMATION:
The radial play on the right side rear axle flange is a normal design characteristic of the new M differential lock style rear axle used on E46 M3 models.

Therefore an M3 differential should not be replaced due to a difference in play (when comparing left to right side differential output flange play) or "excessive" flange play since this will not eliminate a drivetrain rattle or knocking noise.

Only if further diagnosis and verification of the noise complaint indicates rear axle damage, should component replacement be considered.

Notes:
A drivetrain rattle or knocking noise during load change, i.e. 1st to 2nd gear shift at low engine speed when the clutch pedal is pressed, is currently being investigated to possibly optimize drivetrain components for noise reduction under this condition.

Drivetrain component replacements such as transmission, rear axle, drive shaft, etc. will not remedy this problem / complaint.

Only if an actual drivetrain component failure is verified should the replacement of that component be considered.

WARRANTY INFORMATION
Information only.






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