Modifications from 1991 model on Note

Before dismantling the transmission always check the amount of wear on the front-rear locking plates (see Vol. IV, Page D39/45-21). If plates are re-used after having been operated for a period, the bearing pin of the counter-bearing bolt must remain in the same position as before. If it has to be reset or if the counter-bearing bolt has to be removed (for instance to rectify a leak), the correct position for re-installing must first be determined.


Determining thickness of plate cluster (with Gylon discs)

If the plates for the front-rear lock are renewed, the plate cluster thickness must be determined.

Adjustment value (new) Wear limit


If the wear limit is reached, replace all inner discs.

Measure entire disc pack.




A = Installed position

Example I

Measured value Height of special tool* Plate cluster thickness

* Marked on tool

Adjustment value Plate cluster thickness Adjusting plate

Example II

Measured value 106.00 mm

Height of special tool* - 81.50 mm

Plate cluster thickness 24.50 mm


* Marked on tool

Adjustment value 26.00 mm

Plate cluster thickness - 24.50 mm

Adjusting plate 1.50 mm


Do not install any outer adjusting plates thinner than 1.3 mm. In Example I, one of the six 1.3 mm thick outer plates must be increased in thickness by 0.6 mm (to 1.9 mm). In Example II, an additional outer plate 1.5 mm thick must be inserted between the inner plate and the pressure plate.

Adjusting counter-bearing for front-rear lock Note

Adjustment is possible only with the measuring cylinder (special tool 9514), and is only necessary if the plates are renewed.

1 - Spacing plunger

2 - Adjusting screw

2a - Measuring groove on adjusting screw

3 - Special tool 9514/1

4 - Locknut (seal with Loctite 222)

5 - Bearing pin (counter-bearing)

5. Screw in the bearing pin until there is no more endplay at the measuring cylinder spacing plunger. In this position, lock the bearing pin with the hex nut (tightening torque 40 Nm) (30 ftlb).

1. The flexible gaiter for the slave cylinder must be installed.

2. Slacken off the measuring cylinder adjusting screw as far as possible (to make it easier to install the measuring cylinder).

3. Attach the measuring cylinder to the transmission.

4. Use the adjusting screw to set the measuring cylinder to 29.5 mm (in the front-rear differential lock measuring range). LS = Front-rear diff. lock measuring range QS = Lateral diff. lock measuring range


911 Carrera 4 Manual Transmission, Controls, Case

Modifications to the longitudinal lock

Following introduction of the Valeo inner discs, the number of discs and the stacking of the disc pack have been modified.

Case Rps Friction Plates

1 =

Wave disc

2 =

Valeo inner disc

3 =

Outer disc (1.3 mm thick

4 =

Outer adjusting disc

5 =

Snap ring

6 =

Thrust plate


Due to the fact that supply of the Gylon inner discs will be stopped in the foreseeable future, the longitudinal lock must be fitted with Valeo friction discs if repairs are required. To do so, replace all friction discs as well as the wave disc and adjust the pack thickness to the specified dimension (26 mm). Combining Gylon and Valeo inner discs is not permissible.

Determining disc pack thickness (with Valeo inner discs)


Due to the transition from Gylon to Valeo inner discs, the stacking of the disc pack has been modified.


Former Gylon disc







New Valeo disc

1. Determine thickness of disc pack.

- Pack thickness (new) = 26.0 - 0.2 mm Wear limit = 25.2 mm

- Measure entire disc pack with wave disc.

- Measure entire disc pack with wave disc.

Porsche 911 Measures


Measurement Special Tool height* Pack thickness

* Engraved on tool


If the wear limit has been reached, all inner discs must be replaced.

Adjust to specified pack thickness

(26.0 - 0.2 mm) at the thrust plate, using the outer adjusting disc (refer to page 34 - 8c).

2. Apply a thin coat of transmission oil to discs before fitting them.

3. Oil bores in carrier plate of inner discs must line up exactly.


911 Carrera 4 Manual Transmission, Controls, Case

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