Cylinder identification

The following identifiers are stamped on the side opposite to the mounting casting (knock sensor bridge):

Cylinder diameter tolerance group, e.g. group 0

and cylinder height tolerance group e.g. height /s\


Each cylinder height tolerance group (5 or 6) is subdivided further into the cylinder diameter tolerance group.

Height dimension H - 0.020

Cylinder diameter + 0.007

Group stampings

82.750 82.750 82.750 82.750

82.770 82.770 82.770 82.770

100.000 100.007 100.014 100.021

100.000 100.007 100.014 100.021

Only cylinders belonging to the same height group (5 or 6) may be fitted on one and the same cylinder bank.

911 Carrera 4 Engine, Crankshaft, Pistons

Installing Piston Pin Circlips with Special Tool 9500 and 9500/1 Pre-assembling Note

Pre-assembling the circlip in the tapered assembly sleeve should always be performed on a solid surface and only immediately before installation in the piston pin boss.

1. Place circlip in the tapered assembly sleeve that its opening is opposite the opening (window) in the tool and press forward with the pressure pad until the ring snaps in the groove of the tool.

The pressure pad may only be guided into the sleeve again after it has been applied on the piston pin boss.

Incorrect handling of the pressure pad could cause the circlip to spring out of the tapered sleeve. Danger of injury!

Installation on Piston

Apply the assembly sleeve on the piston pin boss and knock or press circlip into groove of the piston with the pressure pad. The small diameter end of the pressure pad serves as a guide in the piston pin.



For weight reasons, piston pins with a smaller diameter (12 mm) are fitted on request. In this case, the pressure plunger (Special Tool 9500/1) must be used in conjunction with the sleeve of Special Tool 9500.

Installing Piston Pin Circlips with Special Tool 9500 and 9500/1

Printed in Germany - XI, 1991

911 Carrera 4

Due to a modification to the wrist pin area, the aperture (window) of the Special Tool may require reworking by approx. 1.5 to 2 mm.


911 Carrera 4 Engine, crankshaft, pistons

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