Porsche 928 1982 Operating and installation instructions

LIST OF CONTENTS
Q
Engine
Crankshaft Bearings. .
Pulleys .
Alternator .
Check Valve . .
Tensioning Roller Carrier
Oil Pump.
Oil Pressure Valve
Power Transmission - Tranraxla System
Vibration Damper
Differential : : : : : :
Reverse Gear Lock-out ..
a
Running Gear
Rear Axle Shafts
Brakes .
Electrical System
Start Relay
Fuel Consumption Indicator
Miscellaneous
Equipment
e Air Conditioner
Survey of Number Ranges
Chassis Numbers
Engine Numbers .
Transmission Numbers
.
Specifications, Adjusting Values, Equipment Survey
Wiring diagrams
Page
2
4
5
6
7
a
10
12
14
16
19
20
26
28
30
31
32
33
34
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42

Porsche 928 - 1982 Models
For 1982, the 928 will have only minor modifications.
Survey of the most important changes:
Engine
0
One piece front main bearing
l
Check valve in cylinder head
0 Modified pressure relief valve
. Modified oil return flow (from shaft seal of oil pump)
. Improved mounting of toothed belt tensioning roller
. Alternator and pulleys
Transmission/Shift/Central Tube
0
Stronger differential shafts
. Reverse gear deflector
0 Vibration damper in central tube
Running Gear
.
Friction welded rear axle shafts
. Floating (fist) caliper brakes for US cars
Equipment
l
Fuel consumption indicator
0 Battery 88 Ah - Standard
l
EC0 Av switch position for climate control system
l
Luggage compartment light
l
Electric seats; automatic forward motion of seat when operating backrest omitted
1

ENGINE - Crankshaft
Crankshaft Bearings
The former split main bearing no. I (pulley end) is replaced by a one piece bearing. The bearing
has a lubrication groove on the inside as well as 4 slots. A heavy dowel pin, located in the crank-
case upper section, prevents turning.
2

ENGINE - Crankshaft
Tightening torque for crankcase studs (third step)
New 1 Old
Studs M 10 50+5Nmor 39.3 + 4.9 Nm or
36 4 ft. Ibs.+ 28.4 + 3.5 ft. Ibs.
Studs M 12 75+5Nmor 58.9 + 4.9 Nm or
54 + 4 ft. Ibs. 42.6 + 3.5 ft. Ibs.
All engines, which have been assembled with the higher tightening torque values, are identified
with an “X” near the case number (matching number for upper and lower case sections).
The tightening torque values 50 + 5 Nm (36 + 4 ft. Ibs.) and 75 + 5 Nm (54 + 4 ft. Ibs.) are
applicable to crankcases, which are marked with “X” and/or those with a one piece front main
bearing.
3

- r
ENGINE - Crankshaft
Pulleys
l
Beginning with 1982 models the alternator will be driven by a “polyrib” belt. Consequently
changes are made on the crankshaft and alternator pulleys. At the same time the alternator ratio was
changed from 1 : 2.15 to 1 : 2.3.
Note the following combinations.
-
UP to and
including 1981
Pulley
Crankshaft Alternator Alternator Drive Belt
I
928.102.116.05 928.603.131 .oo 928.603.113.03 999.192.135.50
92a.io2.i30.02 928.603.131 .oo 928.603.113.03 999.192.135.50
From 1982 92a.io2i39.02 928.603.145.02 928.603.114.00 999.192.214.50
92a.io2.i39.03 928.603.145.02 928.603.114.00 999.192.214.50
0
4

ENGINE - Electrical
Alternator
The 928 has a new alternator, rated at - 14 V - 90 A.
The cover and wire harness have also been changed.
5

ENGINE - Oil Supply, Tappets
Check Valve
A spring-loaded ball check valve (arrow) is installed in the oil supply bore to the cylinder heads.
The valve prevents return flow of the oil
(on a stopped engine) from the supply bore
for the hydraulic tappets.
This feature prevents the development of
tappet noise when engine is stopped for a
long time.
The valve cannot be installed in older cylinder
heads.

ENGINE - Timina
0
Tensioning Roller Carrier
The mounting of the tensioning roller carrier on the water pump housing is stronger.
The diameter of the bearing pin and bushing have been increased from 10 to 12 mm (0.394 to
0.472”); at the same time the width of the bearing eye was increased from 23 to 25 mm
(0.905 to 0.984”).
It is possible to retrofit older engines with the modified tensioning roller carrier.
0
Old
New
0
7

ENGINE - Lubrication
Oil Pump
Up to now the oil return bore from the shaft
seal led into the intake end of the pump.
Because of this led, it had been possible for
the pump to take in air through the shaft
seal.
-. -
TO prevent this, the return flow bore in the pump body has been modified in such a manner
that oil can flow directly
into the oil sump.
The crankcase lower section
has a return bore in the
area of the suction bore for
the oil oumo.

ENGINE - Lubrication
Oil pump body with modified oil return bore
I
i
Crankcase lower section with return bore
Note: Oil pumps of former version (oil return bore to pump intake) can be used on the “new”
crankcase, however, the new pump cannot be used on a “old” style crankcase.
9

ENGINE - Lubrication
Oil Pressure Valve
When casting tolerances in the suction bore for the pressure relief valve piston were unfavorable,
it had been possible for the oil pump to take in air through vent bore (5) and relief bore (2).
1 - Crankcase lower section
2 - Relief or return flow bore
3 - Case mating surface
4 - Crankcase upper section
5 - Vent bore
6 - Pressure relief valve piston
7 - Overflow bore
T - Supply to thermostat
P - Oil pressure from oil pump
R- Return flow to intake bore of oil pump
To prevent this, the relief bore (2) has been shortened in the area of the vent bore - see detail “A”.
At the same time the overflow bore (7) has been moved forward far enough to cover the vent
bore.
0
10

ENGINE - Lubrication
The crankcase with modified casting is marked with the Cast No. 928.202.209.0R
(formerly 928.202.203.8R) on the flywheel end.
When “rattling tappets” are reported as a complaint, an installation of pressure relief valve piston
with a sealing ring, will help rectify the problem.
The sealing ring will prevent taking in air via the vent bore.
Only available as spare part.
I(D
11

POWER TRANSMISSION - Transaxle System
Transaxle System with Vibration Dampar
In central tube (1) there is a vibration damper (2), which by way of its elastic mount (3) counter-
acts the twisting oscillation of the entire transaxle system.
Bending oscillation is caused by unbalanced rotating parts of the drive train.
Although the crankshaft, flywheel, clutch and starter gear ring as well as the torque converter
are balanced in the plant prior to assembly, residual unbalance can produce vibration, which will
be noticed on cars with manual transmission at approx. 4200 rpm and with automatic transmission
at 3300 rpm.
The cast iron vibration damper with rubber spring elements designed for the bending resonance
makes the transaxle system insensitive to residual unbalance and permits the replacement of
separate components, e. g. during repair, without “assembly balancing” (balancing of flywheel +
clutch + starter gear ring together).
For cars with manual the transmission the vibration damper is located in the central tube between
the 2nd and 3rd guide bearings (5).
For cars with automatic transmission the vibration damper is installed in the central tube behind
the 2nd guide bearing.
Central tube with vibration damper for manual transmission:
1 -Central tube
2 - Vibration damper
3 - Rubber spring element
4 - Central shaft
5 - Guide bearing
12
0 I

POWER TRANSMISSION - Transmission
Tightening Torque of Lock Nut
The tightening torque of lock nut (1) has
been increased from 150, 180 Nm
(108.. 130 ft. Ibs.) to280 Nm
(230 ft. Ibs.).
The higher tightening torque value can
also be applied on older transmissions
during repairs.
Introduction date of the higher tightening
torque in standard production was
October 31, 1980.
1 - Lock nut
2 - Reverse gear
3 - Bearing assembly
@ Steel Pipe Layshaft
The layshaft fixed in the transmission case
is made of steel pipe to save weight.
The end of the pipe visible on the outside of
the transmission is sealed with a light alloy
dug (A).
13

POWER TRANSMISSION - Transmission
c
Differential
The shaft for the small differential gears is stronger.
The former shaft with lubricating grooves in the area of the differential gears had a diameter of
18 mm (0.709”).
The new shaft’s diameter is 21 mm (0.827”) and it has no lubricating grooves.
Because of the shaft modifications, the following parts also had to be changed:
Small differential gears (2)
Threaded parts (1)
Differential ’
14

POWER TRANSMISSION - Transmission
Friction Plates in Limited Slip Differential
A ZF limited slip differential with 40 % locking effect is available as optional equipment for
manual transmission type G 28.05 as well as for automatic transmissions A 22.02 and A 22.04.
The arrangement of friction plates has been changed; only one molybdenum-coated inner plate is
installed per side.
New order of plates per side:
1. Trust ring, case hardened steel
2. Outer plate, case hardened steel
3. Inner plate, molybdenum-coated
steel
4. Outer plate, steel, variable
thickness
5. Outer plate, steel,
2 mm (0.079”) thick
6. Diaphragm spring steel*
7. Thrust washer
* The installation position of the diaphragm spring will influence the operating noise of the
limited slip differential!
The grinding noise can be reduced considerably by installing diaphragm spring (6) with its small
diameter pressing against outer plate (5).
This installation position is standard since March 28, 1980.

POWER TRANSMISSION - Transmission, Shift
Reverse Gear Lock-out
The five forward speeds and reverse gear are shifted in
3 planes. The 1st gear and reverse gear are.located on
the first plane.
To prevent grinding or even engaging reverse gear when
upshifting quickly from 1st to 2nd gear, a mechanical
lock, (A), is now employed.
In addition to a pawl mechanism, a positioning spring
(B) is mounted on the inner selector rod so that the
shift lever can always be moved easily into the 4th -
5th gear plane.
16

POWER TRANSMISSION - Transmission, Shift
Figure 1 shows the inner selector lever in neutral position of 4th and 5th gear plane.
All gears can be engaged from this position without difficulty.
Fig. 2
If 1st gear or reverse gear is engaged, paw1 (a) will be lifted by selector arm (E).
In so doing the weak leak spring (D) must also be lifted. Both gears, 1st gear and reverse gear,
are easy to engage from neutral position.
Fig. 3
If 1st gear is engaged, the locking pawl will spring back to its original position (Fig. 1).
If the selector arm would now be moved from 1st gear toward 2nd gear (or reverse gear!), the
locking pawl would prevent engaging reverse gear. The selector arm will be deflected by the pawl
and guided to 2nd gear.
It is possible to shift from reverse gear directly into 1st gear, e. g. when parking, since when
reverse gear is engaged the pawl is only lifted, and cannot move to the locking position.
17

POWER TRANSMISSION - Transmission, Shift
Inner selector rod (C) with
positioning spring (B) and
double selector arm (E).
Also visible is the selector shaft
for 2nd and 3rd gears.
The pawl mechanism (A and D)
is bolted in the upper transmission
case cover.
View in Transmission from
Above:
Visible is the selector rod for
4th and 5th gears, the inner
selector rod (Cl, the double
selector arm (E) as well as
positioning spring (B), the free
end of which is mounted under-
neath the selector rod for 4th
and 5th gears.
c
I
18