Wheels/Steering/Brakes - Vibrations and Chatter
TO: OUR MERCEDES-BENZ PASSENGER CAR DEALERSDATE: May 1986 REF. NO. 40/56
SUBJECT: MEASURES TO ELIMINATE VIBRATIONS MODELS 124 AND 201
A. VIBRATIONS AT HIGHWAY SPEEDS MODELS 124 AND 201
B. STEERING WHEEL VIBRATION WHEN APPLYING BRAKES MODEL 124.030
C. BRAKE CHATTER MODEL 201
A. Vibrations at Highway Speeds, Models 124 and 201
In case of tire vibration complaints perform the following jobs in the order listed. Upon completion of each job, perform interim check to avoid unnecessary work.
1. Check wheels for out-of-round condition
2. Balance wheels on dynamic wheel balancer
3. Rebalance wheels on vehicle
Procedure
1. Check wheels for out-of-round condition
If the vertical runout is greater than 0.8 mm and the lateral runout greater than 1.0 mm, measured at the tread and sidewall - respectively, corrective steps must be taken.
Rotate tire on wheel so highest point of rim coincides to lowest point on tire. Remove tire from rim and generously coat beads of tire with soapy solution for easier shifting. Remount tire onto rim and shift to desired position. To assure proper seating of beads, inflate tire to 4 bar (58 psi) maximum and then reduce to recommended level.
2. Balance wheels on dynamic wheel balancer
Balance wheels on dynamic balancing machine to obtain a reading of "zero" after installing the weight. Check balance once more with wheel installed in a position that is off-set two bolts from the previous position.
NOTE: In case there is still a vibration condition after test driving the vehicle, rebalance the wheels on the vehicle.
3. Rebalance wheels on vehicle
Rebalance wheels on vehicle only after previously balancing them dynamically and if there is no runout.
To effectively rebalance the wheels on the vehicle, observe the following:
- Vehicle must be on solid ground.
- Vehicle doors must be closed.
- Drive the rear wheels via vehicle engine only, to avoid damage to the rear axle differential.
- Weights placed on outer rim can only be changed by a maximum of 20 grams, otherwise the overall balancing will be adversely affected.
NOTE: Before installing a balancing weight on the wheel, utilize the wheel centering play to reduce any residual imbalance by:
a) Turning the wheel so lightest point is at bottom.
b) Loosening all wheel bolts with wheel in this position and retightening them, observing wheel torquing sequence.
B. Steering Wheel Vibration When Applying Brakes, Model 124.030
Steering wheel vibration may occur when gently applying the brakes at highway speeds.
In case of complaints about the above-mentioned situation, replace the one piece rear torsion rubber bushing of both front axle lower control arms with the modified two piece rear torsion rubber bushing.
Procedure
1. Remove lower control arms.
2. Remove rubber bushings using removal and installation tool 124 589 00 43 00.
FIGURE 1 - TWO-PIECE REAR TORSION RUBBER BUSHING:
3. Install modified, two-piece rubber bushing using installer 201 589 06 33 00. When installing the new two-piece rubber bushing, make sure that the flat surfaces of the bushings (arrows, Figure 1) are vertical.
4. Check and align front wheels.
C. Brake Chatter, Model 201
In case of complaints about brake chatter, it may be attributed to corroded rear axle brake discs. Clean the brake discs of the rear axle using cleaning pads 201 589 01 28 00. If corrosion is too extensive, replace rear axle brake discs.
Special Tool Information
Tool Name Tool Number
Group/Category Price*
Removal and installation tool 124 589 00 43 00
Installer 201 589 06 33 00
Cleaning pads (rear brakes) 201 589 01 28 00
*subject to change
Parts Information
Quantity Part Name
Part Number
2 Repair kit for control arm bearing
124 330 03 75
2 Brake disc
201 423 12 12
Time Allowance:
According to Time Guide Fiche