Tightening torques for brake hydraulics

Location

Thread

Tightening Torque Nm (ftlb)

Booster circuit (brake pressure booster and differential lock control)

Steel pressure pipe at pressure reservoir, brake booster, valve block and pump assembly

10x1

14-16(10-12) (steel pipes)

Copper pressure pipe at valve block, hose and lock cylinder

10x1

12 -14 (9 -10) (copper pipes)

Return line at valve block (hollow screw)

M 10 x 1

16(12)

Threaded coupling (miniature measuring union) at pressure reservoir

M 10 x 1

14-16(10-12)

Master cylinder circuits

Brake pressure pipe at master cylinder, brake hose, brake pressure regulator, distributor, brake caliper and hydraulic unit

M 10 x 1

12 - 14 (9 - 10) (copper pipes)

Brake power controller to angle bracket

M 10 x 1

14(10)

Brake caliper

Connecting pipe at brake caliper

M 10 x 1

12(9)

Bleed valve at brake caliper

M 10 x 1

8-12(6-9)

Location

Thread

Tightening Torque Nm (ftlb)

Pump assembly

Pump assembly mount

M 6

10-13(7-10)

Pressure warning switch on pump assembly

M 25

26 (19)

Brake booster

Screw plug in master cylinder

M 10x1

12 - 16 (9 - 12)

Brake pressure regulator to bulkhead

M 8

23 (17)

Master cylinder to adapter* on brake booster

M 8

23 (17)

* Do not dismantle this adapter

Master Cylinder Piston Adapter

11582

86/937

Information About Four Piston Fixed Calipers

Installation Notes

Brake caliper sections must never be separated.

Piston seals, dirt scraper rings and spring plates can be replaced on an assembled fixed caliper.

Heat mounting screws to about 150° C (300° F) with a hot air blower to remove the spring plates, since the screws are installed with a cement. Use new screws for installation. Coat screw threads lightly with Loctite No. 270. Brake cylinder paste Unisilikon TK 44 N 2 must be used for the installation of brake pistons.

(This is also applicable retroactively for other brake calipers when repairing.) Unisilikon paste is available from Parts (Part No. 000.043.117.00).

In order to be able to check the installed position of brake calipers with installed brake pads, fixed calipers have an arrow indicating the brake disc's direction of rotation above the Porsche trademark.

11582

86/937

X = Screws - never loosen or tighten

Information About Four Piston Fixed Calipers 47 - 03

Printed in Germany - III, 1989

Replacing Brake Fluid / Bleeding Brakes and Lock Control General Information

Since brake master cylinder circuits, consisting of the push rod circuit (for front axle) and intermediate piston circuit (for rear axle) with the ABS hydraulic control unit, are completely independent of the booster circuit (brake booster and lock control), brake fluid replacing and bleeding procedures are divided into different jobs (see next page).

Hydraulic Brake Booster Schematic Symbol
709//1

Brake master cylinder circuits (exception 3) Booster circuit (brake booster and lock control)

1+2 To axial and lateral lock cylinders (Q and L)

3 Feed to clutch master cylinder

4 Pump assembly

5 Pressure reservoir

6 Valve assembly (solenoids for axial and lateral locks)

7 Brake booster

8 ABS hydraulic control unit

Information

Use only new brake fluid DOT 4.

Total brake fluid change quantity approx. 1.6 I.

- Brake fluid change interval and fluid grade have been modified as of MY '93. For details, refer to page 47-101 (911 Carrera 2).

The brake fluid reservoir is subdivided into chambers approx. as from the middle section downwards.

Procedure/subdivision

1. Brake fluid change (brake, lock control and clutch) / Bleed brake master-cylinder circuits*.

2. Bleed lock cylinders and pressure lines insofar as the hydraulic system was opened after the valve block for lock actuation.

3. Bleed the lock or brake booster circuit insofar as parts of the booster circuit were replaced or if the system (also suction side of the pump assembly) was opened.

Further to 1: (Brake fluid change)*

The brake fluid change is subdivided into two steps.

1 st step: Change brake fluid of the brake master-cylinder circuits and clutch hydraulics (conventional). Also valid for bleeding of the brake master-cylinder circuits and clutch hydraulics.

2nd step: Change the brake fluid of the booster circuit (brake booster and lock control).

Operate the lock solenoid valve with system tester 9288 and remove brake fluid at each lock cylinder.

* Bleeding the brake master-cylinder circuit and the clutch hydraulics: Same procedure as for 1st step for the brake fluid change.

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