122-L5E2R-04

911 (964)
Technical Information
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Brake Booster/Brake Master Cylinder
Vehicle Type:
911 Carrera 2 (964)/911 Targa (964)/911 Speedster (964)
Model Year:
As of 1990 up to 1994
Subject:
Replacing brake booster during repairs
Information:
If the brake booster on the 911 Carrera 2/Targa/Speedster (964) needs to be replaced, the replacment
brake booster will be a 911 (993) version.
During conversion, the brake master cylinder, mounting saddle and (push rod) joint screw must be
replaced ( Figure 1). The power steering pressure and return lines may also have to be replaced.
Figure 1
Parts Info:
PCG.355.182.01
 Brake booster, set
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Parts list:
Figure 2
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993.355.163.04
1x
Brake master cylinder holder  Figure 2 -1-
993.355.495.02
1x
Mounting saddle  Figure 2 -2-
993.355.023.10
1x
Brake booster  Figure 2 -3-
964.355.287.06
1x
Push rod  Figure 2 -4-
993.355.301.00
1x
Seal  Figure 2 -5-
993.355.910.00
1x
Brake master cylinder  Figure 2 -6-
993.347.449.01
1x
Return line  Figure 2 -7-
PCG.355.910.00
2x
Brake line adapter  Figure 2 -8-
———
1x
964.356.555.00
1x
Damping element comprising  Figure 2 -9-:
1 x hexagon-head bolt, M8 x 55 (900.074.139.03)
2 x washer (900.151.008.02)
2 x washer (999.025.903.00)
2 x damping piece (964.355.485.00)
1 x lock nut (900.910.003.04)
1 x sleeve (964.355.483.00)
Clamp for pressure and return lines  Figure 2 -10-
999.166.076.01
1x
Safety clip, small  Figure 2 -11-
999.507.396.40
1x
Brake line holder  Figure 2 -12-
993.347.448.11
1x
Pressure line Figure 2 -13-
993.355.212.00
1x
900.025.007.03
5x
Seal between brake master cylinder and brake booster (not
shown)
Washer (not shown)
999.084.425.02
2x
Lock nut securing mounting saddle to brake booster
900.910.003.04
3x
Lock nut
999.025.903.00
2x
Washer (not shown)
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911 (964)
Technical Information
Materials:
Tools:
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964.356.557.00
1x
Rubber mounting for pressure and return lines (not shown)
900.123.026.20
4x
Sealing ring, 12 x 16 (not shown)
944.347.467.00
2x
Cable clip (not shown)
999.512.346.00
1x
Hose clamp for return hose (not shown)
999.166.077.02
1x
Safety clips
993.555.545.00
1x
Felt strips (not shown)
999.591.880.40
1x
Brake line holder (not shown)
900.075.085.02
3x
Hexagon-head bolt, M8 x 20 (not shown)
993.347.473.00
1x
Line bracket (not shown)
———
x
Brake fluid
———
x
Hydraulic oil
4
9718 PIWIS Tester I "The Hammer"
9900 PIWIS Tester III "PT3G"
VAS 6860 or Locally Available Brake Bleeder/Filler
Work Procedure: 1
Preparatory work:
1.1
Extract brake fluid from reservoir.
1.2
Remove wheels.
1.3
Loosen push rod on the reversing lever.
1.3.1
Pull bellows  Figure 3 -1- off the
cover  Figure 3 -2- ( Figure 3
-a-).
3
– Steering gear
Figure 3
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1.3.2
Remove safety clip  Figure 4 -1-.
Pull out bolt  Figure 4 -2-.
Guide the push rod  Figure 4 -3out of the reversing lever  Figure
4 -4-.
Figure 4
1.4
Remove underbody panelling  Figure 5 -1,
2, 3-.
1
2
3
2
– Front axle
– Center tunnel
– Fuel pump
Remove brake master cylinder.
Figure 5
2.1
Remove brake master cylinder holder.
2.1.1
Unscrew nut  Figure 6 -1-.
2.1.2
Unscrew hexagon-head bolts 
Figure 6 -2-.
2.1.3
Remove brake master cylinder
holder  Figure 6 -3-.
Figure 6
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Technical Information
2.2
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4
Unscrew cap screws  Figure 7 -1- on the
brake master cylinder.
Figure 7
2.3
Unscrew hexagon nuts  Figure 3 -1- from
brake master cylinder.
Remove brake fluid feed lines  Figure 8 -2from brake master cylinder.
3
Remove mounting saddle.
Figure 8
3.1
3.2
Loosen mounting saddle.
3.1.1
Pull vacuum hose  Figure 9 -1out of the brake booster  Figure 9
-a-.
3.1.2
Unscrew hexagon-head bolts 
Figure 9 -2-.
Remove power steering pressure and return
lines.
Figure 9
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3.2.1
Loosen hose clamp  Figure 10
-3-.
1
2
– Pressure line
– Return line
Pull off return line  Figure 10 -a-.
Disconnect threaded connection 
Figure 10 -4- from pressure line.
Close off openings using suitable
stoppers or use a collecting
container.
Figure 10
3.2.2
Unscrew hexagon nut  Figure 10 -5- and remove holding clamp  Figure 10 -6-.
3.2.3
Move the mounting saddle  Figure
11 -a- so that the banjo bolts 
Figure 11 -1- on the steering gear
are accessible.
Unscrew banjo bolts.
3.2.4
Unclip and remove pressure and
return lines from the holder on the
steering gear.
Figure 11
3.2.5
4
Swivel mounting saddle with brake
booster downwards  Figure 12
-a- and remove it  Figure 12 -b-.
Assemble new mounting saddle.
4.1
Remove reversing lever from standard
mounting saddle.
Figure 12
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4.1.1
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4
Unscrew hose clamp  Figure 13
-1-.
Pull cover  Figure 13 -2- off the
mounting saddle  Figure 13 -3-.
Figure 13
4.1.2
Remove safety clip  Figure 14 -1and pull out the bolt.
Remove safety clip  Figure 14 -2and pull out the bolt.
Remove reversing lever  Figure
14 -3-.
Figure 14
4.2
Position standard reversing lever  Figure
15 -1- on the fork of the mounting saddle 
Figure 15 -2-.
Insert standard bolt  Figure 15 -3- through
the clevis bracket and reversing lever.
Fit new safety clip (999.166.077.02) 
Figure 15 -4-.
Figure 15
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4.3
Technical Information
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Join mounting saddle  Figure 16 -1- and
brake booster  Figure 16 -3- using a new
seal  Figure 16 -2-.
Figure 16
4.4
Tighten new hexagon nuts (999.084.425.02)
 Figure 17 -2-.
Tightening torque 23 Nm (17 ftlb.)
Use new washers (900.025.007.03).
Figure 17
4.5
Insert standard bolt  Figure 18 -3- through
the clevis bracket on the push rod  Figure
18 -2- and reversing lever  Figure 18 -1-.
Fit new safety clip (999.166.076.01) 
Figure 18 -4-.
Figure 18
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4.6
5
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Affix felt tape in the marked area (widest
circumference of the brake booster).
Remove tucker stud.
Figure 19
6
5.1
Pull brake line holder  Figure 20 -1- off the
tucker stud.
5.2
Cut tucker stud using side cutters.
5.3
Apply corrosion protection on bare surfaces.
Replace line bracket on the steering gear.
Figure 20
6.1
Unscrew hexagon socket head bolt  Figure
21 -1-. Remove line bracket  Figure 21 -2-.
Figure 21
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6.2
Technical Information
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Remove cable clip  Figure 22 -1(944.347.467.00) from the old line bracket
and fit it in the new line bracket  Figure 22
-2-.
Secure new line bracket with a hexagon
socket head bolt  Figure 22 -3-.
7
Install mounting saddle.
Figure 22
7.1
Insert mounting saddle with brake booster 
Figure 23 -1- ( Figure 23 -a-) and swivel it
up  Figure 23 -b-.
Figure 23
7.2
Position mounting saddle  Figure 24 -1so that the connections on the steering gear
 Figure 24 -2- are accessible. Secure it to
prevent it from falling down, if necessary.
7.3
Install power steering pressure and return
lines.
Figure 24
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7.3.1
Clip cable clip (944.347.467.00) 
Figure 25 -1- into the holder on the
pressure line.
7.3.2
Screw pressure and return lines
onto the steering gear using banjo
bolts  Figure 25 -2- and new
sealing rings (900.123.026.00).
Only tighten banjo bolts slightly.
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Figure 25
7.3.3
Clip pressure and return lines 
Figure 26 -1- into the new holder 
Figure 26 -2-.
Figure 26
7.3.4
Screw pressure line  Figure 27
-1- together in the centre tunnel.
Tightening torque 25 Nm
(19 ftlb.)
Push on return line  Figure 27 -2and secure with a new hose clamp
(999.512.346.00).
7.3.5
7.3.6
Secure pressure and return lines
to the threaded bolt using a new
rubber mounting (964.356.557.00)
and a new clamp (964.356.555.00
 Figure 27 -3-.
Figure 27
Tighten banjo bolts on the steering gear.
Tightening torque 20 Nm (15 ftlb.)
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7.4
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Fit cover  Figure 28 -1- over the wheel
arch access point on the mounting saddle
 Figure 28 -2-.
Tighten hose clamp  Figure 28 -3-.
Figure 28
7.5
Secure mounting saddle  Figure 29 -1- to
the front axle housing  Figure 29 -2-.
Tightening torque 23 Nm (17 ftlb.)
Figure 29
7.6
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Replace push rod.
7.6.1
Disengage tension spring  Figure
30 -1-.
7.6.2
Remove safety clip  Figure 30
-2-.
7.6.3
Loosen lock nut  Figure 30 -3- on
the brake pushrod.
7.6.4
Remove joint screw  Figure 30
-4- from brake pedal.
7.6.5
Pull out push rod  Figure 30 -5-.
7.6.6
The new push rod is installed in reverse order to removal.
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Figure 30
911 (964)
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7.7
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Secure push rod on the reversing lever.
7.7.1
Insert bolt  Figure 31 -2- through
the swivel head on the reversing
lever  Figure 31 -4- and push rod
 Figure 31 -3-.
7.7.2
Tighten safety clip  Figure 31 -1-.
Figure 31
7.7.3
7.8
8
Fit bellows  Figure 32 -1- on the
cover  Figure 32 -2-.
Fit vacuum hose into the brake booster.
Install brake master cylinder.
8.1
Assemble brake master cylinder.
Figure 32
8.1.1
Unscrew and remove screw plugs
 Figure 33 -2-.
Screw brake line adapter  Figure
33 -3- securely into the brake
master cylinder.
Tightening torque 12 Nm
(9 ftlb.) +4 Nm (+3 ftlb.)
8.1.2
Tighten screw plugs  Figure 33
-1-.
Tightening torque 12 Nm
(9 ftlb.) +4 Nm (+3 ftlb.)
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Figure 33
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8.2
Insert brake master cylinder and secure with
new washers  Figure 34 -1- and M8 lock
nuts  Figure 34 -2-.
Tightening torque 23 Nm (17 ftlb.)
8.3
Carefully bend the brake line until the cap
screw in the brake line adapter can be
screwed in by hand. Tighten cap screw.
Tightening torque 13 Nm (9.5 ftlb.)
+/-1 Nm (+/-0.5 ftlb.)
8.4
Fit brake fluid feed lines into the brake master
cylinder.
8.5
Install brake master cylinder holder.
8.5.1
Figure 34
Screw brake master cylinder
holder  Figure 35 -1- onto the
front axle housing using new
washers (900.025.007.03)
and new hexagon-head bolts (N
010.240.11)  Figure 35 -2-. Only
tighten hexagon-head bolts slightly.
Figure 35
8.5.2
Connect brake master cylinder
holder and brake master cylinder
as shown.
1
2
3
4
5
6
8.5.3
8.6
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– Hexagon-head bolt, M8 x
55 (900.074.139.03)
– Washer (900.151.008.02)
– Washer (999.025.903.00)
– Damping piece
(964.355.485.00)
– Lock nut
(900.910.003.04)
– Sleeve (964.355.483.00)
Figure 36
Secure brake master cylinder holder to the front axle housing.
Tightening torque 23 Nm (17 ftlb.)
Secure brake lines with two holders.
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8.6.1
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Secure brake lines in the area where
the tucker stud was removed 
Figure 37 -arrow- using a holder
(999.591.880.40)  Figure 37
-1-.
Figure 37
8.6.2
9
Secure brake lines in the mounting
saddle area  Figure 38 -2- using a
holder (999.507.396.40)  Figure
38 -1-.
Concluding work:
9.1
Bleed the brake system.
9.2
Fit wheels.
Tightening torque 130 Nm (96 ftlb.)
9.3
Bleed the steering and check for leaks.
Figure 38
9.4
Install underbody panelling  Figure 39 -1,
2, 3-.
1
2
3
9.5
– Front axle
– Center tunnel
– Fuel pump
Check the brake pushrod (brake pedal)
and brake light switch setting and make
adjustments if necessary.  PIWIS Information system/Document title 4602
Figure 39
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Technical Information
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47013100:
Converting brake system
Includes:
Removing and installing front and rear wheels, underbody
covers (3 x), brake master cylinder, mounting saddle with
brake booster, and push rod, replacing pressure and return
lines on steering gear, bleeding the steering system
Without:
Bleeding the brake system
Labor time: 332 TU
47010750:
Bleeding the brake system
Without:
Removing and installing wheels
Labor time: 110 TU
Important Notice: Technical Bulletins issued by Porsche Cars North America, Inc. are intended only for use by professional automotive technicians who have attended Porsche service training
courses. They are written to inform those technicians of conditions that may occur on some Porsche vehicles, or to provide information that could assist in the proper servicing of a vehicle. Porsche special
tools may be necessary in order to perform certain operations identified in these bulletins. Use of tools and procedures other than those Porsche recommends in these bulletins may be detrimental to the
safe operation of your vehicle, and may endanger the people working on it. Properly trained Porsche technicians have the equipment, tools, safety instructions, and know-how to do the job properly and
safely. Part numbers listed in these bulletins are for reference only. The work procedures updated electronically in the Porsche PIWIS diagnostic and testing device take precedence and, in the event of a
discrepancy, the work procedures in the PIWIS Tester are the ones that must be followed.
© 2018 Porsche Cars North America, Inc.
Mar 1, 2018
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