1997 ACURA NSX steering wheel

Steering Gearbox

Motor and Power Assist Mechanism

A motor is housed inside the gearbox housing. It consists of a yoke with a permanent magnet fixed in it, a rotor with a

field coil, and brushes which pass electricity to rotor commutators. The motor is on the rack shaft of the steering gearbox.

The drive current from the control unit flows through the power relay and fail-safe relay to the brushes of the motor.

The drive current flows to rotor commutators through brushes, exciting the field coil of the rotor and rotates the rotor with

the magnetic action of the permanent magnet inside the yoke. The rotor rotates in the opposite direction when the direc-

tion of drive current is reversed.

The rotation torque of the motor is transmitted to the ball screw throught the helical gear. The rotation torque on the ball

screw is converted into assist thrust in the direction of steering rack by the recirculating ball screw. The mechanical advan-

tage of the recirculating ball screw, compaired to a conventional rack and pinion, acts to reduce the steering force to the

steering rack through the joint, to lessen the steering effort required at the steering wheel.

Recirculating Ball Screw

The recirculating ball screw is constructed so that steel balls roll between the screw shaft and the nut, and those coming

out of the screw face enter the screw groove again through a tube for recirculation. The rotation torque on the shaft is

converted into thrust in an axial direction as the slope of the screw shaft presses against the nut through the steel balls.

Since the torque conversion is made in this method through the screw shaft and the steel balls, the friction is small, high

transmission efficiency is obtained for both the forward and backward directions, and the steering feels identical to the

ordinary manual steering.

Furthermore, since the force from the backward direction (force pressing the steering rack) is converted into the rotation

torque of the screw shaft, instantaneous kick-back from the road surface will rapidly rotate the motor. In such a rapid rota-

tion, the inertia of the motor increases, which acts to reduce the kick-back. Any great kick-back will be transmitted from the

steering rack to the torque sensor on the pinion, which acts to twist the pinion shaft in the same direction as the input

direction of kick-back. As a result, the motor operates the kick-back to reduce assist force.ProCarManuals.com

Inspection
Steering Whee l Rotationa l Pla y
1. Plac e th e fron t wheel s i n a straigh t ahea d position ,
an d measur e th e distanc e th e steerin g whee l ca n b e
turne d withou t movin g th e fron t wheels .
2 . I f th e pla y exceed s th e servic e limit , chec k al l steer -
ing components .
Power Assis t Chec k Wit h Vehicl e
Parked
Turn th e steerin g whee l wit h a sprin g scale . Rea d th e
measuremen t whe n th e fron t wheel s o r steerin g whee l
start t o move .
Steerin g Gearbo x Adjustmen t
1. Loose n th e rac k guid e scre w locknut .
Seriou
s burn s ma y resul t i f yo u touc h an y
coolin g component s whe n th e coolin g syste m is hot .
2. Tighten , loose n an d retighte n th e rac k guid e scre w
two time s t o 4 N- m (0. 4 kgf-m , 2. 9 Ibf-ft) , the n bac k i t
of f
3. Tighte n th e locknu t o n th e rac k guid e scre w wit h
th e specia l tool .
4 . Chec k fo r tigh t o r loos e steerin g throug h th e com -
plete turnin g travel .
5. Rechec k steerin g assist .
LOCKNU T WRENCH , 4 0 m m
0791 6-SA5000 1
ProCarManuals.com

Steering Whee l
Remova l
Airbag Remova l
Stor e a remove d airba g assembl y wit h th e
pa d surfac e up . I f th e airba g i s improperl y store d fac e
down , accidenta l deploymen t coul d prope l th e uni t wit h
enoug h forc e to caus e seriou s injury .
NOTE : Befor e removin g th e steerin g wheel , mak e sur e
th e fron t wheel s ar e straigh t ahead .
SR S component s ar e locate d i n thi s area . Revie w th e
SR S componen t locations , precautions , an d procedure s
i n th e SR S ( sectio n 24 ) befor e performin g repair s o r ser -
vice .
1. Disconnec t bot h th e negativ e cabl e an d positiv e
cabl e fro m th e battery .
2 . Remov e th e acces s pane l fro m th e steerin g whee l
lowe r cover , the n remov e th e shor t connector .
3 . Disconnec t th e connecto r betwee n th e airba g an d
cabl e reel .
4 . Connec t th e shor t connecto r t o th e airba g 3 P con -
nector .
5. Remov e th e Tor x bolt s usin g a Tor x T3 0 bit , the n
remov e th e driver' s airba g assembly .
ProCarManuals.com

Steering Wheel

Removal (cont'd)

7. Disconnect the connectors from the horn and cruise

control set/resume switches, then remove the cable

reel 3P connector from its clips.
8. Remove the steering wheel nut.

9. Remove the steering wheel by rocking it slightly

from side-to-side as you pull steadily with both

hands.ProCarManuals.com

4. Connect the horn connector.
Installation

NOTE: Before installing the steering wheel, make sure

the front wheels are straight ahead.

CAUTION:

• Be sure to install the harness wires so that they are

not pinched or interfering with other car parts.

• Do not replace the original steering wheel with any

other design, since it will make it impossible to prop-

erly install the airbag. (Use only genuine Honda

replacement parts.)

• After reassembly, confirm that the wheels are still

straight ahead and that steering wheel spoke angle

is correct. If minor spoke angle adjustment is neces-

sary, adjust the tie-rods only. Do not remove and

reposition the steering wheel.

Confirm that the driver's airbag assembly

is securely attached to the steering wheel; otherwise,

severe personal injury could result during later airbag

deployment.

1. Before installing the steering wheel, center the

cable reel.

Do this by first rotating the cable reel clockwise

until it stops.

Then rotate it counterclockwise (approximately two

turns) until:

— The yellow gear tooth lines up with the mark on

the cover.

— The arrow on the cable reel label points straight

up.
2. Install the steering wheel.

NOTE: Be sure the steering wheel shaft engages

the cable reel.

3. Attach the cruise control set/resume switches 4P

connector to the steering wheel clips.ProCarManuals.com

Steering Gearbo x
Removal/Installatio n
NOTE: Befor e removin g th e steerin g gearbox , mak e
sur e th e fron t wheel s ar e straigh t ahead .
1 . Remov e th e steerin g join t cover .
2 . Remov e th e steerin g join t bolts , an d disconnec t th e
steerin g join t b y movin g th e join t towar d th e col -
umn .
3. Loc k th e steerin g shaf t wit h ignitio n ke y t o kee p th e
steerin g shaf t position .
4 . Rais e th e fron t o f th e vehicle , an d plac e safet y
stand s in th e prope r location s (se e sectio n 1 ).
5 . Remov e th e fron t wheels .
6 . Remov e th e cotte r pi n fro m th e castl e nut , an d remov e
the nut .
7. Instal l th e 1 0 m m he x nu t o n th e bal l joint . B e sur e
tha t th e 1 0 m m he x nu t i s flus h wit h th e bal l join t
pi n end , o r th e threade d sectio n o f th e bal l join t pi n
migh t b e damage d b y th e bal l join t remover .
NOTE : Remov e th e bal l join t usin g th e bal l join t
remover , 2 8 mm . Refe r t o pag e 18-2 1 fo r ho w to us e
th e bal l join t remover .
BALL JOIN T REMOVER , 2 8 m m07MA C-SL0020 0
8. Separat e th e tie-ro d bal l join t an d knuckl e usin g th e
specia l tool .
CAUTION : Avoi d damagin g th e bal l join t boot .
NOTE : I f necessary , appl y penetratin g typ e lubri -
can t t o loose n th e bal l joint .
9 . Remov e th e foldin g spar e tir e an d spar e tir e holde r
plate .
10 . Disconnec t th e batter y negativ e terminal , the n dis -
connec t th e positiv e termina l an d remov e th e bat -
tery .
11 . Remov e th e spar e tir e holde r an d floo r unde r cover .
ProCarManuals.com

Outline
System Description

Role of System

The NSX/NSX-T traction control is a variable system designed to enhance traction during acceleration and cornering. It

does so by determining the optimum amount of wheel spin for any given driving situation, then suppressing surplus

engine power accordingly.

This version of TCS has a lateral acceleration (Lg) sensor and a deceleration control function to improve traction control

during acceleration and deceleration while cornering. When downshifting quickly to a very low gear on a slippery surface,

the driving wheels tend to slip because of engine braking, resulting in lower directional stability. To counteract this, the

deceleration control function controls engine braking with the TCS control unit.

Construction and Function

The TCS control unit gets signals about the vehicle's speed, direction, and road conditions from sensors at the wheels and

the steering column. Based on these signals, the control unit will determine the optimum amount of wheel spin. Because

the system is variable, the control unit may determine, depending on the driving conditions, that some wheel spin is bene-

ficial (thus enhancing straight-line acceleration), or that no wheel spin is beneficial (thus enhancing cornering). For any

given driving situation, the control unit will determine the amount of wheel spin best suited to the driver's needs and, if

necessary, will then signal the throttle actuator and Engine Control Module (ECM) to reduce engine power.

The system is automatically "ready" whenever the engine is started, but can be manually canceled with the TCS switch.

However, once activated, the system cannot be canceled until it is once again in the ready state.

Components:

• Wheel sensors: The TCS "shares" the wheel sensors with the ABS. The wheel sensors transmit wheel speed signals to

the TCS through the ABS control unit.

• Steering angle sensor: The steering angle sensor signals the TCS control unit about the amount of steering angle.

• Lateral acceleration (Lg) sensor: The Lg sensor detects the lateral acceleration of the vehicle and signals the TCS con-

trol unit.

• TCS control unit: The TCS control unit detects the driving condition signals from the sensors and, if necessary, signals

the throttle actuator and the Engine Control Module (ECM). This version has a lateral acceleration (Lg) sensor, which

improves the traction control performance during cornering.

• Throttle actuator: The throttle actuator opens and closes the throttle valve according to the traction control signal from

the Engine Control Module (ECM).ProCarManuals.com

Construction and Function

TCS Control unit

Acceleration Control

When the drive wheel speed exceeds the vehicle speed by a given amount, the TCS control unit judges that the drive

wheels are slipping, and it outputs the traction control signal to reduce engine power.

Deceleration Control

When the drive wheel speed drops below the vehicle speed by a given amount, the TCS control unit judges that the drive

wheels are slipping, and it outputs the traction control signal to control engine braking properly.

Handling Control

Based on signals about driving wheel and driven wheel rotational speeds, the control unit calculates the car's "yaw" rate

(the turn rate of the car's body). Based on signals from the steering angle sensor, the control unit also calculates the yaw

rate expected by the driver. If the difference between actual and expected yaw rates is substantial —that is, if the direction

of the car's body will exceed the driver's expected line — the control unit signals the throttle actuator, which closes the

throttle valve, thus reducing engine power and maintaining the expected line.

Rough Road Control

Based on signals from the wheel sensors, the control unit detects a rough road based on frequency of wheel rotational

vibration. The control unit then signals the throttle actuator to relax engine power, thus improving acceleration efficiency.

Grip Control

Based on signals about wheel speed and lateral acceleration, the control unit determines the efficiency of the grip of the

tires on the road and signals the throttle actuator to relax engine power if necessary, thus improving grip.ProCarManuals.com