Body:
In appearance from the front the Z3 coupe is identical to the roadster.
-- The passenger compartment is now enclosed with a metal roof.
-- A rear hatch attached to the roof with hinges allows access to the rear cargo area.
-- The third brake light is integrated into a rear window wind deflector.
-- The rear hatch window has an electric defogger as well as a rear window wiper. It cannot be
opened separately.
-- The frameless side door windows are different in shape from the roadster and include
BMW's "drop down" function for sealing. Please note that the side windows have
approximately 15mm of glass showing when they are fully lowered. Do not attempt
adjustment.
-- A power tilting glass moonroof is optional as well as a range of roof rack accessories.
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-- The radio antenna is a 17 inch rubber aerial, raked back and mounted at the rear of the roof.
Engine:
The Z3 coupe 2.8 utilizes the new M52TU B28 engine with 193Hp (see TRI 11 75 98). The M
coupe utilizes the S52 B32 engine with 240Hp.
Transmission:
The Z3 coupe 2.8 is available with both the S5D 310Z 5-speed manual or the A4S 270R
automatic. The M coupe is only available with the ZF 5-speed manual (see 97 new model update
hand-out part A).
Differential/Rear Axle:
The Torsen Differential is used by BMW for the first time in the Z3 coupe. It is a limited-slip
differential that operates without a multi-disc system.
The name Torsen comes from the words Torque Sensing.
This limited-slip differential was developed by the American engineer Vernon Gleasmann and is
manufactured by Zexel in Belgium.
The Torsen differential has a 25% locking value.
Scope of service/repair
The differential's internal components are not serviceable individually. Replace with an exchange
unit if repairs are necessary. Parts that remain serviceable include:
-- Drive flange seals, pinion seal, speed pulse generator, and rubber mounting.
The fluid used is a lifetime fill of BMW synthetic SAF-XJ final drive oil (see SIB 33 01 92 ).
This is the only gear oil approved for top-up or refill. The oil fill capacity for this differential is 1.5
qts. (note:Tightening torque for fill/drain plug is 70Nm).
Design/function
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The Torsen differential consists of the following components:
-- Differential cage, 4 pairs of planetary gears, 1 pair of sun gears and a thrust washer.
As in a conventional differential, the drive pinion still drives the ring gear which is bolted to the
differential cage. The differential cage transmits the power to the planetary gears which now
assume the function of the previous differential pinions. The planetary gears are fitted in pairs
horizontally in the differential cage.
The differential cage has openings (1) for the purpose of lubricating the internal parts. In order
for the planetary gears (3) to fit, the differential cage (2) is machined on the inside so that each
pair has its own pocket.
The pair of gears are engaged on both sides when located in the pocket.
During slip-free straight ahead driving the planetary gears are carried by the differential cage and
do not rotate themselves.
Four pairs of planetary gears are housed in the differential cage.
(1) Differential cage lubrication holes
(2) Differential cage
(3) Planetary gear pairs
A pair of sun gears (1) is installed in the center of the differential cage (3).
The sun gears assume the function of the previous side axle gears and are engaged with the
planetary gears.
The two sun gears are separated from each other with a thrust washer (2).
(1) Sun gears
(2) Thrust washer
(3) Differential cage
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Each planetary gear is engaged on both sides with the corresponding second planetary gear but
is engaged only on one side with the sun gear. This arrangement provides the necessary speed
compensation between the right and left axle when cornering.
The principle of the Torsen differential is based on internal friction produced between the contact
surfaces of the planetaries and sun gears. The pitch of the helical cut planetary gears and the
contact surface of the sun gears determine the amount of slip allowed.
Advantages of the Torsen differential include a smoother torque distribution than an on-off clutch
type differential and a good compatibility with traction control systems.
The Torsen also has a low noise level and less internal wear due to the absence of clutches, and
the use of a planetary gear set.
Suspension:
Suspension systems for the Z3 coupe 2.8 and the M coupe will be virtually the same as the
roadster models, with single pivot Macpherson strut front axle and semi-trailing arm rear axle.
The biggest changes will come to the M coupe with specially calibrated shocks, increased front
caster, firmer spring rates, and the rear anti-roll bar which has been increased from 18.5mm to
19.0mm.
Brakes:
The brake system for the coupes will be the same as the roadsters.
With the introduction of the M coupe, ASC will be available on both models.
Wheels/Tires:
Standard wheels on the Z3 coupe 2.8 will be the same 16in. double-spoke wheels as the
roadster. Tires will be 225/50ZR 16 performance radials.
The new optional 17in. radial spoke wheels are 7.5 in. wide at the front and 8.5 in. at the rear.
Tire sizes are 225/45ZR-17 and 245/40ZR-17 respectively.
The M coupe has as standard equipment the 17 in. M roadster 5 spoke wheels, 7.5 in. wide and
225/45ZR-17 tires in the front. Rears are 9.0 in. wide with 245/40ZR-17 tires.
Interior:
The Z3 coupe and the M coupe have the same instrument panel as the Z3 2.8 and the M
roadster respectively.
The instrument cluster for the 2.8 has the
finish in black with black rings and "coupe"
script nameplate. As an option an
aluminum finish cluster with black trim
rings will be available.
The M coupe (illustration) has the same
instrument cluster as the M roadster,
black with chrome rings, and the "M
coupe" script nameplate below the
tachometer.
Sport seats are standard on both models.
Interior color schemes are the same as the roadsters; solid colors for the 2.8 and two-tone color
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coordinated leather interior for the M coupe. Both feature the higher grade Nappa leather over
the roadsters "Oregon" grade.
The partition between the rear seats and
the cargo area has a forward facing
storage box (1).
In the cargo area a carrier box (1) for the
CD player is located on the right side
behind the seat partition.
A cargo net (2) and luggage cover (3) are
also included.
The rear speakers (1) are located in the
headliner above the cargo area.
Refer to repair manual section
65 13 100 for removal and installation
instructions.
The battery location in the trunk floor along with tool storage is the same as on the roadsters.
Specifications: General
2.8 M
Curb weight 1280 kg/2888 lb. 1370 kg/3131 lb.
Weight dist.
Front/Rear 50.4% : 49.6% manual 50.0% : 50.0%
50.1% : 49.9% auto.
Wheelbase 2446 mm/96.3 in 2459 mm/96.8 in.
Length 4025 mm/158.5 in. 4025 mm/158.5 in.
Width 1740 mm/68.5 in. 1740 mm/68.5 in.
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Height 1306 mm/51.4 in. 1280 mm/50.4 in.
Track width
Front 1413 mm/55.0 in. 1422 mm/55.6 in.
Rear 1494 mm/58.7 in. 1492 mm/58.8 in.
Trunk capacity 206 ltr./7.2 cu. ft. 206 ltr./7.2 cu. ft.
Fuel tank capacity 51 ltr/13.5 gal. 51 ltr/13.5 gal.
Rear axle ratio 3.15:1man 4.10:1auto 3.23:1
)
