Porsche 928 S4 Technical Specifications

 

 

 

4-Speed-Automatic Transmission A 28

 

Type

Equipment

installed in

Model Year

 

A 28/04

 

4 speed

 

928 S USA/Japan

 

1985

 

A 28/05

 

4 speed

 

928 S Europe/R.o.W.

rear axle transm. ratio 14:33

 

1985

 

A 28/06

 

4 speed

 

928 S Europe/R.o.W.

rear axle transm. ratio 13:33

 

1985

 

A 28/07

 

4 speed

 

928 S USA/Japan

 

1986

 

A 28/08

 

4 speed

 

928 S Europe/R.o.W.

rear axle transm. ratio 14:33

 

1986

 

A 28/09

 

4 speed

 

928 S Europe/R.o.W.

rear axle transm. ratio 13:33

 

1986

 

A 28/11

 

4 speed

 

928 S Australia,

M-298/299

 

1986

 

A 28/12

 

4 speed

 

928 S4 USA

 

1987/88

 

A 28/14

 

4 speed

 

928 S4 Europe/R.o.W.

 

1987/88

 

A 28/16

 

4 speed

 

928 S4 worldwide

 

1989

 

 

 

 

General Data

A 28.04/07/12

A 28.05/06/09/11/14/16

 

Design

 

Fully automatic 4-speed sun-and-planet transmission

 

Ratios

 

1st gear

2nd gear

3rd gear

4th gear

Reverse gear

 

A 28.04/05/06/06/08/09/11/12/14

 

3.6760

2.4120

1.4360

1.0000

5.1390

 

A 28.16

 

3.87

2.25

1.44

1.00

5.59

 

Final drive

 

Drive pinion without hypoid displacement

 

Final drive ratio

 

15:33 i = 2.200

 

14:33 i = 2.357 (A 28.05/08)

13:33 i = 2.538 (A 28.06/09/

11/14/16)

 

Stall speed

 

A 28.04/07 =

1650…2050 1/min

 

A 28.05/06/08/09/11 =

2200…2600 1/min

 

A 28.12 =

1750…2150 1/min

 

A 28.14/16 =

1750…2150 1/min

 

Capacity, rear axle final drive

 

approx. 2.7 l (’87 models onward, approx. 3.0 l hypoid transmission oil.)  API classification GL5 (MIL-L 2105 B)

SAE 90

 

Capacity, autom. unit with converter

 

Total capacity = approx. 8.0 l (’87 models onward, approx. 9.3 l).  Capacity for fluid change with converter = approx. 6.0 l (’87 models onward, approx. 7.3l)

ATF – Dexron II D

 

 

 

Pressure Values in Bar, ’87 Models Onward

 

Test pressure

Transmission Type A 28.12/14/16

Measuring Instructions

 

Modulating pressure*

 

4.2 + 0.05

 

 

ATF temp. approx. 80°C.  Selector lever in pos. “D”, driving speed approx. 140 km/h,  vacuum line disconnected at modulating pressure cell.

 

Operating pressure

 

16.0 + 1

 

 

ATF temp. approx. 80°C.  Selector lever on D, engine running at 1400 rpm, parking brake engaged and foot brake actuated.

Max. test duration 5 sec. vacuum hose disconnected at modulator unit.

 

Governor pressure

 

A 28.14/16

approx. 0.2

 

approx. 1.1

approx. 2.0

approx. 2.7

 

A 28.12

0.17

 

0.96

1.74

2.35

 

 

at 20 km/h

 

at 50 km/h

at 100 km/h

at 150 km/h

 

Selector lever in pos. “D”, vehicle rolls in partial load range, vacuum line disconnected at modulating pressure cell.

 

* N o t e

If local constraints preclude testing the car at approx. 140 km/h (88mph), measurements may be carried out at approx. 50 km/h (31 mph).

As both versions use different final drive ratios, governor pressures differ for USA/R.o.W. versions.  The USA governor rotates slower at given driving speed.

Standardized transmission used worldwide from 1989 model year.

 

 

 

Gear Shift Points in km/h

 

 

Transmission Type

A 28.04/07/12

Transmission Type

A 28.16

Accelerator pedal position

 

km/h

 

km/h

 

km/h

 

km/h

Selector lever position

Full throttle “D” 1-2-1

Full throttle “D” 2-3-2

Full throttle “D” 3-4-3

Full throttle “2” 1-2

58…64

109…125

190…211

58…64

28…24

54…47

131…115

-

41…50

102…117

169…188

53…58

30…23

49…43

144…128

-

Kick-down “D” 1-2-1

Kick-down “D” 2-3-2

Kick-down “D” 3-4-3

Kick-down “2” 1-2

62…68

126…143

207…216

69…75

45…39

122…106

203…183

-

59…61

123…125

192…195

59…61

48…43

120…105

186…167

-

 

Note: All speed specifications are approximate values.

 

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