1991 BMW 5 SERIES Settings

9Remove the screws securing the throttle
housing to the main body (see illustration).
10Prise out the intermediate throttle link. If
this proves difficult, unscrew the nut and
disconnect the lever from the primary throttle
spindle, taking care not to disturb the return
spring (see illustration).
11Separate the throttle housing from the
main body, and remove the gasket (see
illustrations).
12With the cover inverted, tap out the float
pivot pins, remove the floats, and lift out the
two needle valves - keeping all the
components identified side for side (see
illustrations).
13Unscrew the bypass fuel jet from the
secondary float chamber, then similarly
remove the jets from the cover - keeping them
all identified for location (see illustrations).
14Clean all the components, and blow all
the internal channels clear using low air
pressure.
15Reassembly is a reversal of dismantling,
but note the following points:
a) Fit the new gaskets and seals supplied in
the repair kit.
b) Before refitting the cover, check that the
choke linkage arm is correctly located in
the lever (see illustration).
c) Check and if necessary adjust the float
settings. Invert the cover, and check thedistance from the contact face (without
gasket) to the top of the float, making sure
that the needle valve spring-tensioned
ball is not depressed (see illustration).
Note that the dimension is different for
the primary and secondary floats (see
Specifications). If adjustment is
necessary, bend the float arm as required.
d) Make sure that the seal is fitted to the top
of the accelerator pump (see
illustration).
Adjustment
Note:Idle speed and mixture adjustments are
covered in Chapter 1.
Automatic choke (2B4)16Check that the automatic choke cover
and housing alignment marks are clearly
visible; if not, make new marks.
17Remove the three screws and withdraw
the metal ring (see illustration).
18Remove the plastic cover, at the same
time disengaging the bi-metal spring from the
control lever (see illustration).
19Fit a rubber band to the bottom of the
control lever. Push the pulldown lever to the
right and use a 4.2 mm diameter drill to check
the distance between the lower edge of the
choke valve and the wall of the carburettor(see illustration). Alternatively apply vacuum
to the pulldown unit to move the lever.
20If adjustment is necessary, turn the screw
on the end of the pulldown unit (see
illustration).
21Refit the cover in reverse order, making
sure that the alignment marks are in line.
Throttle positioner (2B4)
22With the throttle in the idle position, check
that the length of the spring on the throttle
positioner is 23.0 ± 1.0 mm. If not, adjust the
nut as required.
23With no vacuum applied (engine stopped)
check that the control travel, measured
between the stop screw and lever, is 5.0 ±
0.5 mm. If necessary, loosen the locknut and
turn the diaphragm rod as required. Tighten
the locknut on completion.
Fuel and exhaust systems 4•13
12.15b To check the float level, measure
the distance between the contact face and
the top of the float12.15a Choke linkage arm located in the
automatic choke lever
12.20 If adjustment is necessary, turn the
screw (arrowed) on the end of the
pulldown unit
12.19 Fit a rubber band (2) to the bottom
of the control lever, then push the
pulldown lever to the right, and use a
4.2 mm diameter drill (1) to check the
distance between the lower edge of the
choke valve and the wall of the carburettor
12.17 Remove the three screws and
withdraw the metal ring
12.15c Accelerator pump seal (arrowed)
12.18 Remove the automatic choke cover,
at the same time disengaging the bi-metal
spring from the control lever
4

Torque wrench settingsNm
Front disc brake caliper
Caliper guide (mounting) bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 to 35
Caliper bracket-to-strut housing bolts
3-Series, E30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
5-Series, E28 (“old-shape”) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
5-Series, E34 (“new-shape”) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Rear disc brake caliper
Caliper guide (mounting) bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 to 35
Carrier-to-trailing arm bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Brake hose-to-caliper fitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 to 17
Master cylinder-to-brake servo nuts
3-Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
5-Series . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 to 29
Brake servo mounting nuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 to 24
Hydraulic line-to-hydraulic brake servo threaded
fittings - 5-Series, E28 (“old-shape”) . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Wheel bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Chapter 1
9•2 Braking system
1 General information
All 3-Series models, and 5-Series E28 (“old-
shape”) models, are equipped with front disc
brakes and either rear drum or rear disc
brakes. 5-Series E34 (“new-shape”) models
have disc brakes front and rear. Front and
rear brakes are self-adjusting on all models.
Some later models are equipped with an Anti-
lock Braking System (ABS); this is described
in Section 2.
Hydraulic system
The hydraulic system consists of two
separate circuits. The master cylinder has
separate reservoirs for the two circuits; in the
event of a leak or failure in one hydraulic
circuit, the other circuit will remain operative.
Brake servo
The vacuum brake servo, utilising engine
manifold vacuum and atmospheric pressure
to provide assistance to the hydraulically
operated brakes, is mounted on the bulkhead
in the engine compartment.
A hydraulic brake servo system is used on
5-Series E28 models. This system uses
hydraulic pressure from the power steering
pump to assist braking.
Handbrake
The handbrake operates the rear brakes,
and is cable-operated via a lever mounted in
the centre console. The handbrake assembly
on rear drum brake models is part of the rear
drum brake assembly, and is self-adjusting.
On rear disc brake models, the handbrake
uses a pair of brake shoes located inside the
centre portion of the rear brake disc, and is
manually-adjusted.
Brake pad wear warning system
The brake pad wear warning system is
linked to a red warning light in the instrumentcluster, which comes on when the brake pads
have worn down to the point at which they
require renewal. DO NOT ignore this reminder.
If you don’t renew the pads shortly after the
brake pad wear warning light comes on, the
brake discs will be damaged.
On some models, the brake pad wear
warning system also includes an early
warning light that comes on only when the
brake pedal is depressed, letting you know in
advance that the pads need to be renewed.
The wear sensor is attached to the brake
pads. The sensor is located at the left front
wheel; on some models, there is another
sensor at the right rear wheel. The wear
sensor is part of a closed circuit. Once the
pads wear down to the point at which they’re
flush with the sensor, the disc grinds away the
side of the sensor facing the disc. Thus, the
wire inside the sensor is broken, and the red
light on the instrument panel comes on.
Always check the sensor(s) when renewing
the pads. If you change the pads before the
warning light comes on, the sensor(s) may still
be good; once the light has come on, renew
the sensor.
Service
After completing any operation involving
dismantling of any part of the brake system,
always test drive the vehicle to check for
proper braking performance before resuming
normal driving. When testing the brakes, try to
select a clean, dry, road with no camber (ie as
flat as possible) and with no other traffic.
Conditions other than these can lead to
inaccurate test results.
Test the brakes at various speeds with both
light and heavy pedal pressure. The vehicle
should stop evenly, without pulling to one side
or the other. Avoid locking the brakes,
because this slides the tyres and diminishes
braking efficiency and control of the vehicle.
Tyres, vehicle load and wheel alignment are
factors which also affect braking
performance.
2 Anti-lock Braking system
(ABS)- general information
The Anti-lock Braking System is designed
to maintain vehicle control, directional stability
and optimum deceleration under severe
braking conditions on most road surfaces. It
does so by monitoring the rotational speed of
each wheel and controlling the brake line
pressure to each wheel during braking. This
prevents the wheels from locking up.
The ABS system has three main
components - the wheel speed sensors, the
electronic control unit, and the hydraulic
control unit. The sensors - one at each wheel
since 1985, but at both front wheels and one
at the rear differential on earlier models - send
a variable voltage signal to the control unit,
which monitors these signals, compares them
to its program information, and determines
whether a wheel is about to lock up. When a
wheel is about to lock up, the control unit
signals the hydraulic unit to reduce hydraulic
pressure (or not increase it further) at that
wheel’s brake caliper. Pressure modulation is
handled by electrically-operated solenoid
valves.
If a problem develops within the system, an
“ABS” warning light will glow on the
dashboard. Sometimes, a visual inspection of
the ABS system can help you locate the
problem. Carefully inspect the ABS wiring
harness. Pay particularly close attention to the
harness and connections near each wheel.
Look for signs of chafing and other damage
caused by incorrectly-routed wires. If a wheel
sensor harness is damaged, the sensor
should be renewed (the harness and sensor
are integral).
Warning: DO NOT try to repair an
ABS wiring harness. The ABS
system is sensitive to even the
smallest changes in resistance. Repairing
the harness could alter resistance values

Torque wrench settingsNm
Front suspension
Strut damper rod nut
Rod with external hexagon . . . . . . . . . . . . . . . . . . . . . . 65
Rod with internal hexagon . . . . . . . . . . . . . . . . . . . . . . 44
Strut cartridge threaded collar . . . . . . . . . . . . . . . . . . . . . . . 130
Strut upper mounting nuts . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Front control arm (3-Series)
Control arm-to-steering knuckle balljoint nut . . . . . . . . . . 64
Control arm-to-subframe balljoint nut . . . . . . . . . . . . . . . 83
Control arm bush bracket bolts . . . . . . . . . . . . . . . . . . . . 41
Lower control arm (5-Series)
Control arm-to-steering arm balljoint stud nut . . . . . . . . . 85
Control arm pivot bolt . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Thrust arm (5-Series)
Thrust arm-to-steering arm balljoint stud nut . . . . . . . . . . 85
Thrust arm through-bolt . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Front hub (wheel bearing) nut . . . . . . . . . . . . . . . . . . . . . . . . 290
Steering arm-to-strut bolts (5-Series) . . . . . . . . . . . . . . . . . . 65
Anti-roll bar (3-Series)
Anti-roll bar-to-connecting link bolt . . . . . . . . . . . . . . . . . 41
Anti-roll bar mounting brackets-to-subframe . . . . . . . . . . 22
Connecting link-to-bracket . . . . . . . . . . . . . . . . . . . . . . . . 22
Connecting link bracket-to-control arm . . . . . . . . . . . . . . 41
Anti-roll bar (5-Series)
Anti-roll bar mounting brackets . . . . . . . . . . . . . . . . . . . . 22
Anti-roll bar link-to-strut housing locknut
Yellow chrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
White chrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Yellow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
10•2 Suspension and steering systems
Torque wrench settingsNm
Rear suspension
Rear shock absorber (3-Series)
Shock absorber-to-upper mounting bracket . . . . . . . . . . 12 to 15
Shock absorber-to-trailing arm . . . . . . . . . . . . . . . . . . . . 71 to 85
Rear shock absorber (5-Series)
Lower mounting bolt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 to 142
Upper mounting nut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 to 24
Upper spring mounting-to-shock absorber locknut . . . . . 22 to 24
Trailing arms (3-Series)
Trailing arm-to-lower mounting . . . . . . . . . . . . . . . . . . . . 71 to 85
Trailing arm-to-anti-roll bar . . . . . . . . . . . . . . . . . . . . . . . . 22 to 23
Trailing arms (5-Series)
Trailing arm-to-rear axle carrier (rubber bush
through-bolt and nut) . . . . . . . . . . . . . . . . . . . . . . . . . . 66
Trailing arm-to-axle carrier connecting link (1983-on) . . . 126
Rear wheel bearing drive flange axle nut (5-Series)
M22 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 to 210
M27 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 to 260
Steering system
Steering wheel retaining nut . . . . . . . . . . . . . . . . . . . . . . . . . 79
Steering column universal joint pinch-bolt . . . . . . . . . . . . . . 22
Steering gear-to-subframe mounting bolts (3-Series) . . . . . 41
Steering box-to-front suspension subframe bolts (5-Series) 42
Track rod end-to-steering arm nut . . . . . . . . . . . . . . . . . . . . 37
Track rod end clamping bolt . . . . . . . . . . . . . . . . . . . . . . . . . 14
Pitman arm-to-steering box (5-Series) . . . . . . . . . . . . . . . . . 140
Steering linkage balljoints (all) . . . . . . . . . . . . . . . . . . . . . . . 37
1 General information
Warning: Whenever any of the
suspension or steering fasteners
are loosened or removed, they
must be inspected and if
necessary, new ones fitted, of the same
part number or of original-equipment
quality and design. Torque specifications
must be followed for proper reassembly
and component retention. Never attempt
to heat, straighten or weld any suspension
or steering component. Any bent or
damaged parts must be renewed.
The front suspension (see illustrations)is a
MacPherson strut design. The struts are
secured at the upper ends to reinforced areas
at the top of the wheel arches, and at the
lower ends to the steering arms/control arms.
An anti-roll bar is attached to the control arms
via connecting links, and to the suspension
subframe (3-Series models) or the underbody
(5-Series models).
The independent rear suspension system
on 3-Series models (see illustration)features
coil springs and telescopic shock absorbers.
The upper ends of the shock absorbers are
attached to the body; the lower ends are
connected to trailing arms. An anti-roll bar is
attached to the trailing arms via links, and to
the body with clamps.
The independent rear suspension system on
5-Series models (see illustration)uses coil-over shock absorber units instead of separate
shock absorbers and coil springs. The upper
ends are attached to the body; the lower ends
are connected to the trailing arms. The rear
suspension of 5-Series models is otherwise
similar to that of 3-Series models: two trailing
arms connected by an anti-roll bar.
The steering system consists of the
steering wheel, a steering column, a universal
joint shaft, the steering gear, the powersteering pump (where fitted) and the steering
linkage, which connects the steering gear to
the steering arms. On 3-Series models, a
rack-and-pinion steering gear is attached
directly to the steering arms via the track rods
and track rod ends. On 5-Series models, a
recirculating-ball steering box is connected to
the steering arms via a Pitman arm, a centre
track rod, the outer track rods and the track
rod ends.
1.1a Front suspension and steering components (3-Series models)
1 Subframe 3 Anti-roll bar link 5 Strut 7 Steering gear
2 Anti-roll bar 4 Control arm 6 Track rod end

REF•8General Repair Procedures
Whenever servicing, repair or overhaul work
is carried out on the car or its components,
observe the following procedures and
instructions. This will assist in carrying out the
operation efficiently and to a professional
standard of workmanship.
Joint mating faces and gaskets
When separating components at their
mating faces, never insert screwdrivers or
similar implements into the joint between the
faces in order to prise them apart. This can
cause severe damage which results in oil
leaks, coolant leaks, etc upon reassembly.
Separation is usually achieved by tapping
along the joint with a soft-faced hammer in
order to break the seal. However, note that
this method may not be suitable where
dowels are used for component location.
Where a gasket is used between the mating
faces of two components, a new one must be
fitted on reassembly; fit it dry unless otherwise
stated in the repair procedure. Make sure that
the mating faces are clean and dry, with all
traces of old gasket removed. When cleaning a
joint face, use a tool which is unlikely to score
or damage the face, and remove any burrs or
nicks with an oilstone or fine file.
Make sure that tapped holes are cleaned
with a pipe cleaner, and keep them free of
jointing compound, if this is being used,
unless specifically instructed otherwise.
Ensure that all orifices, channels or pipes
are clear, and blow through them, preferably
using compressed air.
Oil seals
Oil seals can be removed by levering them
out with a wide flat-bladed screwdriver or
similar implement. Alternatively, a number of
self-tapping screws may be screwed into the
seal, and these used as a purchase for pliers or
some similar device in order to pull the seal free.
Whenever an oil seal is removed from its
working location, either individually or as part
of an assembly, it should be renewed.
The very fine sealing lip of the seal is easily
damaged, and will not seal if the surface it
contacts is not completely clean and free from
scratches, nicks or grooves. If the original
sealing surface of the component cannot be
restored, and the manufacturer has not made
provision for slight relocation of the seal
relative to the sealing surface, the component
should be renewed.
Protect the lips of the seal from any surface
which may damage them in the course of
fitting. Use tape or a conical sleeve where
possible. Lubricate the seal lips with oil before
fitting and, on dual-lipped seals, fill the space
between the lips with grease.
Unless otherwise stated, oil seals must be
fitted with their sealing lips toward the
lubricant to be sealed.
Use a tubular drift or block of wood of the
appropriate size to install the seal and, if the
seal housing is shouldered, drive the seal
down to the shoulder. If the seal housing isunshouldered, the seal should be fitted with
its face flush with the housing top face (unless
otherwise instructed).
Screw threads and fastenings
Seized nuts, bolts and screws are quite a
common occurrence where corrosion has set
in, and the use of penetrating oil or releasing
fluid will often overcome this problem if the
offending item is soaked for a while before
attempting to release it. The use of an impact
driver may also provide a means of releasing
such stubborn fastening devices, when used
in conjunction with the appropriate
screwdriver bit or socket. If none of these
methods works, it may be necessary to resort
to the careful application of heat, or the use of
a hacksaw or nut splitter device.
Studs are usually removed by locking two
nuts together on the threaded part, and then
using a spanner on the lower nut to unscrew
the stud. Studs or bolts which have broken off
below the surface of the component in which
they are mounted can sometimes be removed
using a stud extractor. Always ensure that a
blind tapped hole is completely free from oil,
grease, water or other fluid before installing
the bolt or stud. Failure to do this could cause
the housing to crack due to the hydraulic
action of the bolt or stud as it is screwed in.
When tightening a castellated nut to accept
a split pin, tighten the nut to the specified
torque, where applicable, and then tighten
further to the next split pin hole. Never slacken
the nut to align the split pin hole, unless stated
in the repair procedure.
When checking or retightening a nut or bolt
to a specified torque setting, slacken the nut
or bolt by a quarter of a turn, and then
retighten to the specified setting. However,
this should not be attempted where angular
tightening has been used.
For some screw fastenings, notably
cylinder head bolts or nuts, torque wrench
settings are no longer specified for the latter
stages of tightening, “angle-tightening” being
called up instead. Typically, a fairly low torque
wrench setting will be applied to the
bolts/nuts in the correct sequence, followed
by one or more stages of tightening through
specified angles.
Locknuts, locktabs and washers
Any fastening which will rotate against a
component or housing during tightening
should always have a washer between it and
the relevant component or housing.
Spring or split washers should always be
renewed when they are used to lock a critical
component such as a big-end bearing
retaining bolt or nut. Locktabs which are
folded over to retain a nut or bolt should
always be renewed.
Self-locking nuts can be re-used in non-
critical areas, providing resistance can be felt
when the locking portion passes over the bolt
or stud thread. However, it should be noted
that self-locking stiffnuts tend to lose theireffectiveness after long periods of use, and
should then be renewed as a matter of course.
Split pins must always be replaced with
new ones of the correct size for the hole.
When thread-locking compound is found
on the threads of a fastener which is to be re-
used, it should be cleaned off with a wire
brush and solvent, and fresh compound
applied on reassembly.
Special tools
Some repair procedures in this manual
entail the use of special tools such as a press,
two or three-legged pullers, spring com-
pressors, etc. Wherever possible, suitable
readily-available alternatives to the manu-
facturer’s special tools are described, and are
shown in use. In some instances, where no
alternative is possible, it has been necessary
to resort to the use of a manufacturer’s tool,
and this has been done for reasons of safety
as well as the efficient completion of the repair
operation. Unless you are highly-skilled and
have a thorough understanding of the
procedures described, never attempt to
bypass the use of any special tool when the
procedure described specifies its use. Not
only is there a very great risk of personal
injury, but expensive damage could be
caused to the components involved.
Environmental considerations
When disposing of used engine oil, brake
fluid, antifreeze, etc, give due consideration to
any detrimental environmental effects. Do not,
for instance, pour any of the above liquids
down drains into the general sewage system,
or onto the ground to soak away. Many local
council refuse tips provide a facility for waste
oil disposal, as do some garages. If none of
these facilities are available, consult your local
Environmental Health Department, or the
National Rivers Authority, for further advice.
With the universal tightening-up of legis-
lation regarding the emission of environmen-
tally-harmful substances from motor vehicles,
most vehicles have tamperproof devices fitted
to the main adjustment points of the fuel
system. These devices are primarily designed
to prevent unqualified persons from adjusting
the fuel/air mixture, with the chance of a
consequent increase in toxic emissions. If
such devices are found during servicing or
overhaul, they should, wherever possible, be
renewed or refitted in accordance with the
manufacturer’s requirements or current
legislation.
Note: It is
antisocial and
illegal to dump
oil down the
drain. To find
the location of
your local oil
recycling
bank, call this
number free.