Longitudinal & Differential Lock Friction Disc - Revised

Group
3

Number
9306

Model
911 C4

Part Identifier
3940

September 28, 1993

Subject:
Longitudinal and differential lock friction disc material modification.

ATTENTION: Service Manager / Service Technician

Models/Transmissions Affected:
911 Carrera 4 w/ G-64 00/01/02





Concern:
The inner drive disc friction material has been changed from "Gylon" to "Valeo" (see Figure 1).

General Information:
For repairs, only the friction discs from "Valeo" are available. This applies to both the longitudinal and differential locks.

Repair Information:
Differential lock:
The "Valeo" friction discs are installed in the differential lock in production as of October 1, 1991 from transmission number: G 64 00 30 01146.

The "Valeo" disc has a different thickness from the former "Gylon" disc. Following this change of the inner disc thickness, stacking adjustment and wear limit specifications have been modified.

When installing "Valeo" friction discs into transmissions manufactured before the above mentioned transmission number (first time installation), all new "Valeo" discs must be used.

IMPORTANT:
Mixing "Valeo" and "Gylon" plates is not permitted.








Modified transmissions are to be marked (to highlight different wear limits) by stamping a large "V" into the transmission housing below the hydraulic cylinder (see Figure 2). Refer to the Workshop Manual Volume 2. page 39-12a, b, c and d.

Setting adjustment before installation:
Pack thickness (new) = 37.9 ± 0.1 mm
Wear limit = 36 mm

Adjustment value and wear limit (friction pack installed):
The adjustment value and wear limit for transmissions with or without adjustable bearing pin is the same:

New adjusting value = 31 mm
Wear limit = 40 mm

Measured with special tool 9514/1. Refer to Workshop Manual Volume 2, pages 39-1 to 39-120.

Longitudinal Lock:
"Valeo" friction discs were installed in the longitudinal locks in production beginning with model year 1993. Former version Gylon and new version "Valeo" friction discs have different thicknesses. However, the total friction packet thickness has not changed.





When repairing longitudinal looks of transmissions, produced before model year 1993, all new version "Valeo" discs and the new wave disc must be installed (see Figure 3). The pack thickness must be adjusted to specified dimension of 26 mm (the same as before).

IMPORTANT:
Combining "Gylon" and "Valeo" friction discs is not permitted.

Adjustment Value and Wear Limit:
The adjustment value and wear limit for transmissions with or without adjustable bearing pin is the same:

Adjusting value = 29.5 mm
Wear limit = 32.5 mm

Measured with special tool 9514/1. Refer to the Workshop Manual Volume 2, pages 34-8c and d.