Porsche 928 S4 Technical Specifications

General:

Conversions

Engine types

Chassis codes

Engine data

Technical data

Testing and Adjusting Specifications

Torque Specifications

Manual Transmission

Automatic Transmission

Suspension:

Axles and Steering

Alignment Values

Braking System

Rims/Tires

Performance Data

Dimensions

Weights

Capacities

Fuses/Relays – 1987/88

Fuses/Relays - 1989

From the Porsche “Technical Specifications” booklet available from 928 Specialists.

928 S4 page

Technical Data – Front Axle, Steering and Rear Axle

Front Axle
Wheel suspension	Independent suspension, double control arm with coil spring and internal damper
Springs	1 coil spring per wheel
Dampers	Double-action dampers
Stabilizers	Ø 28 x 4 mm (tubular stabilizer)
Steering	Rack and pinion power steering with tie rods
Steering wheelØ	380 mm
Steering wheel ratio (in center position)	17.75:1
Turning circleØ	11.5 m
Track circleØ	9.6 m
No. of steering wheel turns from lock to lock	3.13
Rear Axle
Wheel suspension	Independent wheel suspension with lower diagonal suspension links and upper wishbones, coil springs and internal dampers
Springs	1 coil spring per wheel
Dampers	Double-action hydraulic dampers
Stabilizer	Ø 22.5 x 3.5 mm (tubular stabilizer)

Wheel Alignment Adjusting Values*

The following values apply to curbweight according to DIN 70020 (car with full fuel tank, spare wheel and tools)

	Adjusting Value and Tolerance	Max. Difference Left to Right
Front Axle
Height setting: From the contact surface to measuring point on rear link bearing	190 – 20 mm **	10 mm
Toe-in unpressed	+ 15’+5’
Track difference at 20° lock	-1°+20’	may only be affected by replacing steering arms
Camber	+30’+10’	10’
Caster	3°30’+30’	20’
Rear Axle
Height setting: From tire contact surface to measuring point on cross member	173 + 10 mm**	10 mm
Toe-in per wheel	+10’+5’	10’
Camber	-40’+10’	10’

*The vehicle alignment settings are applicable to the actual vehicle ride height only (see repair manual pp. 44-1 etc.)

**The height setting values apply to new vehicles. Used vehicles may be up to 10 mm lower, i.e. the tolerance may deviate by minus 10mm. This must, however, be the same for both axles.

Technical Data – Braking System

Description	From Mod. 86 Specifications/ Remarks	Wear Limit
New brake disc thickness front rear	32 mm 24 mm
Brake discs – Min. thickness** after machining front rear	30.6 mm 22.6 mm	30.3/30 mm 18.6/22 mm
Thickness tolerance for brake disc max.	0.02 mm
Lateral runout for brake discs max.	0.05 mm
Lateral runout for installed brake discs max.	0.1 mm
Max. surface finish after machining	0.006 mm
Play on brake pedal with brakes bled and engine stopped (footbrake arm without stop)	Approx. 10 mm determined by permanently set clearance at points inside braking unit
Parking brake*** (handbrake)	Drum brake applied mechanically on both rear wheels
Parking brake drum dia.	180 mm	181 mm
Brake shoe width	25 mm
Brake liner surface area per wheel	85 cm^2
Brake liner thickness	4.5 mm	1 mm

* Fixed calipers with pistons of dia. 42/36 mm were installed in some cars (USA, Canada, Australia and Arabian countries) in the 1987 model year.

The front-axle brake calipers with 44/36 mm dia. Pistons can be retrofitted in 86 models only in pairs.

** Brake disks may only be machined symmetrically, i.e. evenly on both sides.

*** 87 models onward, parking brake liners made of asbestos-free material (Energit 559). The liners can be retrofitted to vehicles earlier than the model year 87 (right-hand and left-hand sides).

Rims, Tires and Tire Pressure

Standard tires		Tires	Rims	ET**
87 mod. onward 928 S4 928 S4 Club Sport	front rear front rear	225/50 VR 16 245/45 VR 16 225/50 VR 16 245/45 VR 16 (with 17 mm washer)	7 J x 16 H 2 8 J x 16 H 2 8 J x 16 H 2 9 J x 16 H 2	65 52.3 60 60
89 mod onward 928 GT	front rear	225/50 ZR 16* 245/45 ZR 16* (with 17 mm washer)	8 J x 16 H 2 9 J x 16 H 2	60 60

* “ZR” 89 model onward

“VR” above 210 km/h, “ZR” above 240 km/h

** rim offset in mm

Tire Pressure in bar (Summer Tires)

Type	928 S4	928 S4 Club Sport 928 GT
Front axle	2.5 bar	2.5 bar
Rear axle	3.0 bar	3.0 bar

Collapsible spare tire until 85 models 2.2 bar, 86 models onward 2.5 bar

Winter tires front 2.5 bar, rear 3.0 bar

Checking wheel Rims

Refer to drawing for radial and lateral runout measuring points on inner and outer rim shoulders.

Max. permissible radial and lateral runout for light alloy rims = 1.0 mm.

Note:

Never straighten distorted wheel rims