Drive/Propeller Shaft - Vibration Reduction
TO: OUR MERCEDES-BENZ PASSENGER CAR DEALERSDATE: May 1986 REF.No. 41/11
SUBJECT: A. CENTERING SLEEVE WITH BRONZE BUSHING ON REAR PROPELLER SHAFT
B. BALANCING NUTS ON REAR AXLE FLANGE FOR REDUCING HUMMING NOISE AT HIGHWAY SPEEDS MODEL 124.030
A. Centering Sleeve With Bronze Bushing On Rear Drive Shaft
Since the end of January 1986, a centering sleeve with bronze bushing (previously a plastic bushing) is installed on the rear propeller shaft. In addition, a modified rear propeller shaft with tighter tolerances at the shaft flange is being installed, thereby eliminating minute propeller shaft imbalances at the rear axle which can cause vibration. The modified propeller shaft can be identified by an orange ring at the rear of the shaft.
Effective Serial Number
Model Chassis End Number
124 1A-171803
B. Balancing Nuts On Rear Axle Flange For Reducing Humming Noise at Highway Speeds
On vehicles built prior to production phase-in, in cases of customer complaints, balancing nuts can be placed at the rear axle flange connection to minimize any vibrations diagnosed after test driving the vehicle. The procedure is outlined on the following pages.
Procedure
1. Raise vehicle on lift just high enough to allow removal of rear wheels.
2. Place wheel chocks to the front and rear of each front wheel.
3. Remove rear wheels.
4. Start engine, engage transmission and accelerate to speed at which complaint was isolated. Using second person, diagnose vibration from rear seat.
5. Raise vehicle and remove wax coating on rear propeller shaft.
FIGURE 1 - PROPELLER SHAFT-REAR AXLE FLANGE:
6. On the flexible coupling disc, number the locations of the 6 bolts (1-6) connecting the propeller shaft flange with the rear axle flange (Figure 1).
FIGURE 2 - BALANCING NUT ON BOLT NO. 1:
7. Install 1.5 gram balancing nut on the exposed thread of bolt no. 1 (Figure 2).
8. Lower vehicle and repeat check for vibration as in step 4.
9. If necessary, remove balancing nut and place on next consecutive bolt until all six locations have been tried. Record the best of the 6 possible locations for the balancing nut.
FIGURE 3 - 3 GRAM BALANCING NUT:
NOTE: In case the procedure in steps 8 and 9 does not produce a satisfactory result, then the 1.5 gram balancing nut must be replaced with a 3 gram nut (arrow, Figure 3).
Re-evaluate the humming noise.
If satisfactory results still cannot be obtained, install (in addition to the 3 gram nut) a 1.5 gram nut on one of the adjacent bolts. Determine the best location by repeating step 4.
For example: In Figure 3 the 3 gram balancing nut is installed on bolt no. 4. The additional 1.5 gram nut should therefore be installed on bolt no. 3 or no. 5, as required.
NOTE: The 5 gram balancing nut is only required in extreme, special cases.
FIGURE 4 - BALANCING NUTS LOCKED IN PLACE:
10. Using a center punch, lock balancing nut(s) against the thread (Figure 4).
NOTE: Washers may be substituted for balancing nuts if they are not available. Always use new self-locking nuts once they were removed.
In addition, on vehicles built prior to production phase-in (see A, Effective Serial Number), a centering sleeve with a bronze bushing may be installed on the rear propeller shaft, but only if satisfactory results cannot be achieved by adding balancing nut(s). Note that the centering sleeve must be lubricated with 6 grams of long-term grease according to page 266.2 of the Service Products Specification binder.
Parts Information
Part Name Part Number
Balancing nut 1.5 gram 124 411 02 72
Balancing nut 3.0 gram 124 411 03 72
Balancing nut 5.0 gram 124 411 04 72
Centering sleeve with bronze bushing 124 410 03 32
Washer DIN 433, 10.5 000433 010505
Washer DIN 125, A 10.5 000125 010518
Nut, self-locking 123 990 07 51
Time Allowance
41-0000/01 Actual time