421119 Removing and installing lower trailing arm
WM 421119 Removing and installing lower trailing arm
Tools
Preliminary work
1. Raise the vehicle. -> 4X00IN Lifting the vehicle Service and Repair
2. Remove wheel. -> 440519 Removing and installing wheel Removal and Replacement
Air suspension
3. On vehicles with air suspension, bleed the corresponding air spring using the PIWIS Tester II 9818. -> 4301IN Bleeding and filling levelling system 4301IN Bleeding and filling the levelling system
Steel suspension
4. On vehicles with steel suspension, release the corresponding steel spring using the spring clamp 9823. -> 427219 Removing and installing rear coil springs
Removing and installing lower trailing arm
Lower control arm component
1. On vehicles with air suspension, carefully unclip the locking lugs -arrows- and press the air spring upwards. The air spring can remain clipped in at the top.
Air suspension locking lugs
2. Unhook level sensor linkage. -> 431955 Replacing rear level sensor 431955 Replacing rear level sensor
Information
If the vibration damper cannot be removed, it is still clamped in the lower trailing arm. If necessary, unscrew the outer threaded joint of the trailing arm.
3. Use an intermediate layer (hard rubber) between the drive shaft and chassis subframe strut (longitudinal strut) so as not to damage the drive shaft. Then remove the lower screw on the vibration damper. Get a second mechanic to help if necessary. -> 429319 Removing and installing rear shock absorber (spring damper) 429319 Removing and installing rear shock absorber (spring damper)
Information
On vehicles with steel springs, the coil spring must be secured to prevent it from falling down BEFORE swivelling the trailing arm down (second mechanic required).
4. Mark the position of the eccentric screw (assembly aid) and remove it.
5. Then loosen the front threaded joint and remove the screw from the bore hole until the trailing arm can be swivelled downwards.
6. Remove outer trailing arm.
CAUTION
Wheel carrier raised incorrectly
- Risk of squashing
- Risk of damage to components
-> Wear personal protective gear.
-> Do not raise the wheel suspension higher than the normal vehicle position (vehicle resting on wheels).
Information
- The entire threaded parts of the axle must be tightened in vehicle position. Vehicle position means: vehicle standing on the wheels, or the wheel suspension is raised with a universal vehicle lift. Dimension -X- , from lower edge of wing to centre of axle corresponds to vehicle position. The current height can be found in -> 4495TW Adjustment values for suspension alignment 4495TW Adjustment values for suspension alignment. Always observe the following points.
Dimension X - centre of wheel to lower edge of wing (rear axle shown)
Steel suspension
- The vehicle position is reached at the rear axle by pre-tensioning the steel spring using spring clamp 9823 to the dimension -X-.
Air suspension
- Vehicle position can be obtained on the rear axle by using PIWIS Tester II 9818 to bleed the relevant air spring and carefully raise the relevant wheel bearing housing until dimension -X- is reached. -> 4301IN Bleeding and filling the levelling system 4301IN Bleeding and filling the levelling system
- Use an intermediate layer (hard rubber)! Do not damage the brake cover plate.
Raising wheel carrier (air suspension), front axle shown with brake disc and caliper fitted
- Screws and nuts are Geomet-coated and must not be greased.
- Grease the toothing of the drive shaft slightly with aluminium paste Optimoly TA.
- Drive shafts must not be left hanging from the joint stop! Tie up.
- Use new screws and lock nuts.
- Observe correct tightening torques and torque angles -> 4X00IN Tightening torques for rear axle 4X00IN Tightening torques for rear axle.
7. Installation is carried out in reverse order.
Subsequent work
Air suspension
1. Follow the relevant installation instructions. -> 434319 Removing and installing rear air spring 434319 Removing and installing rear air spring
Steel suspension
2. On vehicles with steel suspension, insert the corresponding coil spring using the spring clamp 9823. -> 427219 Removing and installing rear coil spring
3. Fit the wheel. -> 440519 Removing and installing wheel Removal and Replacement
4. Perform suspension alignment. -> 449503 Suspension alignment, complete 449503 Suspension Alignment, Complete