1999 BMW 525i Workshop Manual

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Driveshaft
4 Driveshaft center slide nut spanner
(Tool No. BMW
26 1 040)
7, 25 1 Ho 4 cv joint removal tool
(Tool No. BMW 26 1 11 0)
support assembly
Driveshaft description
4 The two-piece driveshaft is connected to the transmission by
a rubber flex-disc and to the rear final drive by a constant ve-
locity (CV) joint.
A universal joint is used at the center of the driveshaft and
the shaft is supported in the middle by a center support
bearing. The bearing is mounted in rubber to isolate vibra-
tion.
- The rear constant velocity joint compensates for fore and
aft movement of the drive line.
Troubleshooting
The source of driveline vibrations and noise can be difficultto pin-
point. Engine, transmission, rear axle, or wheel vibrations can be
transmitted through thedriveshaftto the car body. Noises from
thecar may be caused by final drive problems, or by faulty wheel
bearings, drive axles, or even
wom or improperly inflated tires.
NOTE-
For drive axle repair information, see 331 Final Drive
Driveshaft noise or vibration may be caused by worn
ordam-
aged components. Check the universal joint for play. With the
driveshaft installed, pull and twist the driveshaft while watch-
ing the joint. The
BMW specification for play is very small, so
almost any noticeable play could indicate a problem.
Check the torque of the fasteners at the flange connections.
Check the rubber of the flex-disc and center bearing for dete-
rioration or tearing. Check the driveshaft for broken or miss-
ing balance weights. The weights are welded tabs on the
driveshaft tubes. In addition to inspecting for faulty driveshaft
parts, the installed angles of the driveshaft should also be
considered.

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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
Driveshaft problems and causes
Symptom Probable cause Corrective action
Vibration when starting off Center bearing rubber deteriorated. Inspect center bearing and rubber. Replace if necessary.
(forward or reverse)
Flex-disc damaged or worn.
Inspect flex-disc. Replace
if necessary.
Engine or transmission mounts
faulty. Inspect engine and transmission mounts. Align or
replace, if necessary.
Front centering guide worn, or driveshaft
Checic front centering guide and replace
if necessary.
mounting flanges out of round.
Check
runout of driveshaft flanges.
Universal joint worn or seized.
Check universal joint play and movement. Replace
driveshaft if necessary.
Driveshaft misaligned. Check driveshaft alignment.
Noise during onloff throttle Final
drive components worn or damaged
Remove final drive and repair. 331 Final Drive
or when engaging clutch. (excessive pinion-to-ring-gear clearance).
Drive axle or CV joint faulty.
Inspect drive axles and CV joints. Repair or replace as
necessary.
331 Final Drive
Vibration at 25 to
30 mph
Front centering guide worn, or driveshaft
Check front centering guide and replace if necessary.
(40 to 50
kmlh). mounting flanges out of round or damaged.
Check runout of driveshaft mounting flanges.
Universal joint worn or seized.
Check universal joint play and movement. Replace
driveshaft if necessary.
Flex-disc damaged or worn.
Inspect flex-disc. Replace if necessary.
Center bearing rubber deteriorated.
Inspect center bearing. Replace if necessary.
Misaligned installed position. Check driveshaft alignment.
Vibration, audible rumble Front centering guide worn, or driveshaft
Check front centering guide and replace
if necessary.
over
35 mph (60 kmlh). mounting flanges out of rouncl or damaged.
Check runout of driveshaft mounting flanges. - -
Mounting flange bolts loose or holes worn.
Remove driveshaft and check transmission output flange
and final drive input flange. Replace if necessary.
Driveshaft unbalanced. Check driveshaft for loose or missing balance weights.
Have driveshaft rebalanced or replace if necessary.
Universal ioint worn or seized.
Check universal ioint
~lav and movement. Reolace ' .. driveshaft if necessary.
Center bearing faulty.
Replace center bearing.
.
Final drive rubber mount faulty.
Inspect final drive rubber mount and repiace if necessary.
Driveshaft misaligned.
Check driveshaft alignment.

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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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4 Remove nuts (arrows) from constant velocity joint mounting
bolts at final drive. Pry constant velocity joint free from final
drive input flange at groove
(A).
- Hang driveshaft rear section from body using stiff wire.
< Do not let driveshaft hang unsupported, as rear CV joint rub-
ber boot (arrow) may be damaged.
4 Remove center support bearing mounting nuts (arrows)
- Remove driveshaft. Pull down on center of driveshaft to
facilitate removal.
CAUTIOI\C
Protect CVjoint with plastic cover.

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260-1 0
/ Driveshaft
Driveshaft, installing
- Prepare CV joint for reinstallation:
Extend joint to limit.
Clean off old grease and fill with fresh grease
Install new seal.
- Bend driveshaft slightly at center universal joint to install
CAUTION-
Do not allow CVjoint seal to become displaced.
- Align matchmarlts on driveshaft to matchmarks on final drive
and transmission flanges.
- Fit constant velocity joint to final drive input flange. Alternate-
ly tighten two opposite nuts to draw constant velocity joint
evenly into the final drive input flange. Once seated, tighten
down remaining nuts.
I CAUTION-
I Do not reuse self-locking nuts. These nuts are designed to be /
I used onlv once. 1
- Insert bolts in front of driveshafl to transmission output
flange. Counterhold each bolt while tightening nut.
CAUTION-
. Do not reuse self-locking nuts. These nuts are designed to
be used only once.
Avoid stressing the flex-disc when torquing the bolts.
Do this by counterholding the bolts and turning the nuts
on the flange side.
- Position center support bearing and install mounting nuts.
Use new self-locking nuts.
- Install heat shields.
- Install rear transmission support crossmember.
- Install exhaust system. See 180 Exhaust System.
Reconnect oxygen sensor wiring harnesses and reattach
wiring harness retainers to rear transmission support
crossrnernber.