Practical procedure when readjusting the drive set

If it is necessary to adjust drive pinion and ring gear, follow the below sequence to ensure an

1. Determine the total thickness of shims "Stot" (Si plus S2) for the specified preload on the tapered

2. Determine the thickness of shim "S3".

3. Split the total shim thickness "Stot" into Si and S2 so that the specified circumferential backlash is present between ring gear and drive pinion.

The aim of this adjustment is to restore the smoothest running position which has been achieved on test equipment in the production line.

To achieve correct results, greatest possible cleanliness for all assembly work and measuring procedures is essential.

When assembling the final drive assembly, it is only necessary to readjust drive pinion and ring gear or drive set if components have been replaced which have a direct influence on the adjustment. Refer to the following table to avoid unnecessary adjustment procedures.


Ring gear (Si + S2)

Drive pinion (S3)


Transmission case



Lateral transmission cover


Large cylindrical roller bearing and four-point bearing for drive pinion



Drive set



Differential housing


Tapered roller bearing for differential


3 - Adjusting shim S3 E - Setting value

Correct results may only be achieved if assembly work and measuring procedures are carried out carefully and with maximum cleanliness.

Adjusting drive set General

The setting of drive pinion and ring gear is a determining factor for the service life and smooth running of the rear-axle drive. Drive pinions and ring gears that have been checked for good tooth contact pattern and low noise in both directions of rotation on special test equipment are therefore matched during prodution. The position at which smoothest running can be achieved is determined by shifting the drive pinion axially, and embossed on the ring gear as setting value "E".

2 = circumferential backlash "F"

3 = matching number

911 Carrera 4 (993)

Final Drive, Differential, Differential Lock

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