1999 BMW 540i Oul

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1 Driveshaft
Further inspection requires removal of the driveshaft. Checlc
the front centering guide on the transmission output flange for
damage or
misalignment. Also check runout at the transmis-
sion output fiange and output shaft, and at the final drive input
fiange. Check the bolt hole bores in the flange for wear and
elongation.
Driveshaft flange
runout (max. allowable)
Transmission
flange
- Axial play 0.10 mm (0.004 in.)
Radial play 0.07
mm (0.003 in.)
Spin the driveshaft center bearing and
check ior smooth op-
eration without play. Check the constant velocity joint
forwear
or play. Checlc the universal joint for wear or binding. If it is
difficult to move or binds, the driveshaft section should be
replaced.
Universal joint
play
Maximum allowable 0.15
mm (0.006 in.)
NOTE-
With the driveshaft installed, the actual amount that the drive-
shaftjoint pivots is limited. For the most accurate test, check
joint
in its normal range of movement.
If inspection reveals nothing wrong with the driveshaft, it may
need to be rebalanced. This can be done by a speciality drive-
shaft repair shop. Also,
checlc driveshaft alignment as de-
scribed below.
NOTE-
Minor driveshaft vibrations can often be corrected simply by
disconnecting the driveshaft at the final drive and reposition-
ing it go", 180" or 270" in relation to the final drive input
flange.
The troubleshooting table below lists symptoms
oi driveshaft
problems and their probable causes. Most of the repair infor-
mation is contained within this repair group. There are refer-
ences to other repair groups, where applicable.

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Driveshaft
Repair kits for the universal joint are not available for BMW
driveshafts.
A worn or damaged universal joint usually require
replacement of the driveshaft.
The driveshaft is balanced to close tolerances. Whenever it is
to be removed or disassembled, the mounting flanges and
driveshaft sections should be marked with paint or a punch
before proceeding with work. This will ensure that the
drive-
shaft can be reassembled and installed in exactly the original
orientation.
1. Rear section of drive shaft
2. Hex bolt, MI2 x 1.5 x 25
3. Knurled bolt
4. Clamp
5. Reinforcement
6. Seal
7. Constant velocity joint
8. Circlip
9. Hex nut
10. Hex bolt, M12x 1.5~58
11. Centering sleeve
12. Flexible disk
13. Self-locking hex nut
14. Front section of driveshaft
15. Center bearing
16. Dust cover (some models)
17. Spacer (some models) -

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Driveshaft, aligning
The alignment of the driveshaft does not normally need to be
checked unless the engineltransmission or the final drive
have been removed and installed. if ail other parts of the
driveshaft have been inspected and found to be okay, but
there is still noise or vibration, driveshaft alignment should be
checked.
There are two important driveshaft alignment checks. The
first is to make sure that the driveshaft runs straight from the
transmission to the final drive, without any variation from
side-
to-side caused by misalignment of the engineltransmission in
its mounts. Make a basic check by sighting along the
drive-
shaft from back to front. Any misalignment should be appar-
ent from the center bearing forward.
To adjust the side-to-side alignment, loosen transmission or
engine mounts to reposition them, then retighten mounts.
The driveshaft should be exactly centered in driveshaft tun-
nel.
The second important driveshaft alignment check is more
complicated. It checlts the amount the driveshaft is angled
vertically at the joints. This angle is
lknown as driveshaft
deflection.
In general, there should be little deflection in the driveshaft
between the engine, the center bearing, and the final drive.
Precise checks require the use of a large protractor or some
other means of measuring the angle of the engine and the fi-
nal drive and comparing these angles to the angle of the
. . driveshaft sections.
- To change the deflection angle, shims can be placed be-
tween the center bearing and the body or between the trans-
mission and its rear support. When using shims to change a
deflection angle, keep in mind that the angle of adjacent
joints will also change. Deflection angles should be as small
as
oossible.

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-.- .
/ Driveshaft Driveshaft, removing
CAUTION-
. Be sure the wheels are off the ground before removing the
driveshak Set the parl(ing brake before removing the
driveshaft.
Once the driveshaft has been removed, the vehicle can
roll regardless of whether the transmission is in gear or
not.
The driveshaft is mounted to the transmission and final
drive
with self-locliing nuts. These nuts are designed to
be used only once and should be replaced during reas-
sembly.
Remove complete exhaust system. See
180 Exhaust
System.
- Remove exhaust heat shields.
- Support transmission with transmission jack.
< Loosen transmission mount nuts (arrows) on real
transmission support crossmember.
- Release wiring harness retainers from rear transmission
support crossmember.
< Remove mounting bolts (arrows) for rear transmission sup-
port crossmember. Slide crossmember rearward to remove.
- Matchmark front and rear driveshaft halves to corresponding
transmission output and final drive input flanges.
4 Remove nuts securing driveshaft mounting bolts at transmis-
sion output flange. Counterhold bolts (arrows) at transmis-
sion flex-disc. Discard old nuts.
- Hang driveshaft front section from body using stiff wire.

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260-1 2
1 Driveshaft
Install new flex-disc using new self-locking nuts. Molded ar-
rows (arrows) on coupling should point towards flange arms.
4 On vehicles with aluminum driveshaft, use coated washers to
prevent contact corrosion.
- Counterhold bolts while tightening nuts.
Tightening torque
Aluminum driveshaft to flex-disc
M12 (use coated washers) 90
Nm (66 ft-lb)
Steel driveshaft to flex-disc
MI0 (8.8 grade) 48
Nm (35 ft-lb)
- MI0 (10.9 grade) 60 Nm (44 ft-lb)
Coated washers - MI2 (8.8 grade) 5027500 . Mi2 (10.9 grade)
M14 81
Nm (60 ft-lb) 100 Nm (74 ft-lb)
140 Nm (103 ft-lb)
- Install driveshaft as described earlier
Center bearing assembly, replacing
The center bearing assembly consists of a grooved ball bear-
ing in a rubber mount. The bearing assembly is pressed
the driveshaft.
- Remove driveshaft. See Driveshaft, removing
- Matchmark front and rear driveshaft sections before
separating.
Remove bolt (arrow) securing front and rear halves of
driveshaft and pull driveshaft apart.
- Remove shim and dust shield, where fitted
- Use puller to remove center bearing assembly from
driveshaft. onto

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- On installation, drive new center bearing firmly to stop.
Reassemble driveshaft using matchmarks made prior to
disassembly.
- Clean threads and install bolt securing driveshaft halves.
Use thread locking compound
LoctiteO or equivalent.
Tightening torque Driveshaft front half to rear half
(use thread locking compound) 97
Nm (72 fl-lb)
- Install driveshaft as described earlier.
Front centering guide, replacing
The front centering guide centers the driveshafl in relation to
the transmission. The guide is press-fit into a cavity in the
front of the driveshafl and slides onto the transmission output
shaft.
No specifications are given
forwear of the guide, but general-
ly the guide should fit snugly on the transmission output shafl.
NOTE-
Some driveshafts have a dust cap installed on the end of the
driveshaft, over the centering guide. The dust cap may be-
come bent or distorted when the driveshaft is removed or
in-
stalled. Damage to the dust cap should not affect the
centering guide and should not be mistaken for guide wear.
- Remove driveshafl as described earlier
- Pack cavity behind centering guide with heavy grease until
grease is flush with bottom edge of guide.
- Insert 14 mm (approximately 9/16 in.) diameter mandrel or
metal rod into guide. Strike guide with hammer to force cen-
tering guide out.
NOTE-
Tlie mandrel should fit snugly in the centering guide so that
the grease cannot escape around the sides of the mandrel.
- Remove old grease from driveshaft, lubricate new centering
guide with molybdenum disulfide grease
(MolykoteO, Long-
term8 2 or equivalent) and drive it into driveshaft.
4 When installing new driveshafl centering guide, be sure seal-
ing lip of guide faces outward. Drive guide into driveshaft to
a protrusion depth of
4 - 6mm (0.16 - 0.24 in.).
- Install driveshaft as described earlier.

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Suspension, Steering and Brakes - ~enerail
The main components of the system are the wheel speed
(pulse) sensors, the
ABSIASC or ABSIDSC control module,
and the hydraulic control unit.
Traction control also comes into operation during decelera-
tion. Decelerating on snowy or icy road surfaces can lead to
rear wheel slip. If a rear wheel starts to drag or lock up, the
ASC system can limit the problem by adjusting throttle, fuel
injection and ignition timing.
4 A switch (arrow) on the center console is used to toggle the
ASC on or off.
NOJE-
Even with the ASC system turned off, if the ASC control mod-
ule senses a difference in wheel speed (one wheel spinning)
the
ASC system applies modulated braling force to the slip-
ping wheel until traction is regained. There is no override of
fuelinjection function.
The ASC system is designed to be maintenance free. There
are no adjustments that can be made. Repair and trouble-
shooting of the ASC system requires special test equipment
and knowledge and should be performed only by an autho-
rized
BMW dealer.
ABSIASC traction
I 1.
control system
Wheel speed sensor
Wheel speed pulse wheel
Brake disk
Brake caliper
ABSIASC hydraulic unit
Brake master cylinder
Pedal operated throttle valve
ASC controlled throttle valve
Engine control module (ECM)
Accelerator pedal
ABSlASC control module

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31 0-8
Front Suspension
Slide strut assembly out of steering lknucltle pinch collar. If
necessary use pry bar.
CA UTIOI\C
Do notpullstrut out of steering knuckle with twisting motion.
This can scratch and damage the strut.
Disassemble and reassemble strut assembly as described
later.
When installing new strut, be sure to align locator letter (A)
on strut body with slot in steering
lknuckle pinch collar (6).
Struts are marked with L for left and R for right.
Remainder of installation is reverse of removal.
Make sure strut shoulder (below locator letter) bottoms out
in steering knuckle pinch collar.
Use new self-locking nuts and bolts.
When attaching stabilizer
lrnk to strut, use a thin wrench to
counterhold
link ball joint while t~ghtening nut.
- Have car professionally al~gned when job IS complete.
Tightening torques
Brake caliper to steering knuckle
110 Nm (81 ft-ib)
Road wheel to hub 120 ti0 Nm (89 t7 ft-lb)
Stabilizer bar
link to strut 65 Nm (48 It-lb)
Steering knucltle pinch bolt at strut 81 Nm (60 It-lb) - mountlng collar
Steering tle rod to steerlng knuckle 65 Nm (48 it-lb)
Strut assembly top to strut tower 24 Nm (18 it-lb)
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