WIS 41.10 Propeller Shaft
Description - Propeller Shaft
W220 Propeller Shafts are of the two-piece design. M-B produced this design because it completely eliminates natural frequency vibrations commonly found in many one piece Propeller Shafts.
The Propeller Shaft Assembly consists of;
- Rubber flex discs which connect the transmission output shaft to the front Propeller Shaft and the rear Propeller Shaft to the rear differential.
- These flex discs absorb torsional vibrations from the engine/transmission and reduce shock load to the Propeller Shaft and rear axles.
- A front Propeller Shaft constructed of an extremely strong tubular section made from a special steel and cold worked for additional strength, which saves weight compared to other designs of drivelines.
- The front Propeller Shaft is connected to the rear Propeller Shaft (same construction to the front shaft) with a universal joint (UJ) and a sliding spline.
- The UJ is a precision bearing, which allows for small angle changes due to initial alignment and engine and transmission movement.
- M-B UJs are an extremely precise design for a universal joint and have considerable torque carrying capacity. Unlike most designs, the roller bearings are contained in a thin shell, stamped from an exotic alloy sheet metal 1 mm thick. It is formed accurately enough to not require subsequent machining and is heat treated sufficiently by the force of the stamping to not require subsequent heat treating. The thinness of this bearing cap allows a large cross and larger roller bearings to be utilized, greatly increasing both strength and bearing life, while keeping size and weight low.
- The rear Propeller Shaft is supported by a centrally located ball bearing which is encased in a soft rubber housing mounted on the vehicle chassis. This housing helps dampen unwanted vibrations, and to some extent both the flex discs and the support housing can be tuned to the specific arrangement of chassis, transmission and rear axle.
- A centre spline is used to accommodate slight dimensional variations between the transmission output flange and the differential input flange.
- Centering Bushes are used to ensure the front Propeller Shaft is perfectly aligned with the transmission output shaft and the rear Propeller Shaft is perfectly aligned with the differential pinion shaft.
- This design causes M-B Propeller Shafts to rotate with the smallest amount of radial run-out possible and with accurate dynamic balancing results in super smooth and quiet performance.
Issues - Propeller Shaft
The following are common issues associated with the W220 Drive/Tail/Propeller Shaft assembly.
- Cracked and fatigued Flexi Discs,
- Worn Centre Bearing,
- Worn Universal Joints (UJ),
- Flat spots on UJ roller bearings. The front and rear Propeller Shafts are only a few degrees out of alignment and hence the UJ does very little work. The needle bearings in the UJ cups do not rotate much and consequently wear flat spots on the needles and bearing surfaces.
- Worn spline,
- Misalignment due to worn engine mounts,
- Staked UJ cups making DIY replacement impossible. (Requires accurate centering on a professional jig and welding.)
Symptoms - Propeller Shaft
- Strong vibrations under acceleration,
- Clunking noises,
- Complete and catastrophic failure of Flex Discs.
Dimensions - Propeller Shaft
W220 2003 Update S500L
Dimensions - Propeller Shaft UJs
- Bearing Cap Diameter: 24mm (0.945")
- Distance Between Bearing Cap Ends: 88 mm (3.465")
Availability - Propeller Shaft UJs
Universal Joint - Propeller Shaft
Because of the unusual size of the M-B UJs they are difficult to source and W220 UJs are not the same as readily available earlier M-B UJ’s. Bakkeren Nederland have two versions of the correct size UJ for W220s listed in their catalogue.
- KR 1.720.114 is an M-B OEM part and
- KR 1.720.117 is a Bakkeren part.
Comparison of Early M-B UJs Versus W220 UJs.
Angle Measurements - Propeller Shaft
Driveshaft bend angles that are outside the specified tolerances can produce drivetrain vibration and rough response to acceleration.
WIS document AR41.10-P-0086IW describes how to measure propeller shaft angular alignment with an electronic propeller shaft inclinometer.