Technical Service Bulletin Mainshaft Seal and Guide Tube

Subject: Mainshaft Seal And Guide Tube        Models: 911 1976

Bulletin Number: 85 – 01

As of the blow VIN’s, the seal and guide tube were modified:

914ES121832 – Coupe

91XES161758 – Targa

918ES1170968 – Cabriolet

Parts Information:


999.113.283.40 – Seal

915.116.087.03 – Guide Tube


999.113.327.40 – Seal                                                                                                                


915.116.087.04 – Guide Tube

The new seal has an additional dust lip and its location in the guide tube has been moved 10mm to assure proper alignment with the shaft.

In case of repair, you should be aware of the following:

  • Only the new seal is available
  • The new guide tube can be installed in all older models including M.Y. 1976.
  • The main shaft with shorter sealing surface were factory installed on transmission up to M.Y 1976 (Fig. 2)
  • Transmissions as of Model Year 1976 could be field repaired using a main shaft with a shorter sealing surface.

Therefore, it is very important to measure the sealing surface (Fig. 2 and 3) before guide tube replacement.

I – Old version mainshaft

II – New version mainshaft


Due to the different location of the seal in the guide tube, the installation tool has been modified (was P381, now P381a).

The old seal installation tool P381 must be used for the old version tube (40mm) and P381a only for the new version (50mm)

Since P381a has a guide tube for the oil seal, the guide sleeve should be held in a vise during the seal installation (Fig. 6) and not on a flat surface.

Coordination of Parts

       Guide Tube – Old 915.116.087.03Guide Tube – New 915.116.087.04Seal – New 999.113.327.40
Mainshaft with small sealing surfaceXX
Mainshaft with large sealing surfaceXX

Note: Before installation of the guide tube/seal into transmission, fill seal between the two lips with chassis grease.

The seal of the guide tube is the same as before, with O-ring, #999.701.359.40

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