wheel torque ACURA NSX 1997 Service Repair Manual

3-13
TDesign Specifications
(cont’d)
ITEMMETRICENGLISH
DIMENSIONSOverall length
Overall width
Overall height
Wheelbase
Track F/R
Ground clearance
Seating capacity4,425 mm 174.2 in
1,810 mm 71.3 in
1,170 mm 46.1 in
2,530 mm 99.6 in
1,510/1,540 mm 59.4/60.6 in
130 mm 5.1 in
2
WEIGHT (USA)
Single plate dry, diaphragm spring
Torque converter
239 cm
237.0 sq in
CLUTCHClutch M/T
A/T
Clutch lining area M/T
Gross Vehicle Weight Rating (GVWR)
NOTES
Gear reduction/DENSO
1.4 kW
12 V
30 seconds
Counterclockwise as viewed
from gear end
4.75 kg 10.47 lbs
ENGINEWater cooled, 4-stroke DOHC VTEC
gasoline engine
90 °V6-cylinder, transverse
93.0 x 78.0 mm 3.66 x 3.07 in
90.0 x 78.0 mm 3.54 x 3.07 in
3,179 cm
3(cc) 194 cu in
2,977 cm3(cc) 182 cu in
10.2
Belt driven DOHC
Forced and wet sump
Premium UNLEADED grade gasoline
with 91 Pump Octane Number
or higher
STARTERType/Make
Normal output
Nominal voltage
Hour rating
Direction of rotation
Weight
WEIGHT (CANADA)Gross Vehicle Weight Rating (GVWR)
Synchronized 6 speed forward 1 reverse
Electronically controlled
4-speed forward automatic 1 reverse
Direct 1 : 1Transmission M/T
A/T
Primary reduction
Manual AutomaticType
3.066 2.611
1.956 1.551
1.428 1.025
1.125 0.684
0.914—
0.717—
3.186 1.909Gear ratio 1st
2nd
3rd
4th
5th
6th
Reverse
Single helical gear
4.062 4.428
TRANSMISSION
Final reduction Gear type
Gear ratio
Type
Cylinder arrangement
Bore and strokeC32B1 engine
C30A1 engine
DisplacementC32B1 engine
C30A1 engine
Compression ratio
Valve train
Lubrication system
Fuel required
M/T 1,630 kg 3,593 lbs
A/T 1,655 kg 3,649 lbs
*04-NSX (61SW004)SEC03(01-16) 9/22/04 1:49 PM Page 3-13
ProCarManuals.com

Service Precautions

Handling of Special Nuts and Bolts

Handling of Tires

• The tires on NSX & NSX-T should not be rotated. The

front wheels are 16" in, diameter and the rear wheels

are 17" in, so they cannot be rotated front-to-rear.

The original-equipment tires on NSX & NSX-T have a

unidirectional tread pattern, so they cannot be rotat-

ed side-to-side.

• The folding spare tire cannot be repaired or removed

from the rim.

Engine Steam-cleaning

(NSX-T only)

When steam-cleaning the engine compartment, keep the

roof holder switch dry. If the roof holder switch gets wet

accidentally, dry it thoroughly with compressed air.
Because many sections on this vehicle are constructed

with aluminum alloys, use only the special "Dacro" type

nuts and bolts recommended by Acura.

NOTE:

• Dacro finish can be identified by gray plating.

• Some Dacro finish bolts have a green coating on the

thread section of the bolt for easier application. This

type of bolt is called a "Torquer" bolt.

• Use of other types of nuts and bolts may cause elec-

trolysis and corrosion, which in turn could cause the

bolt to loosen.

Gray plating: "Dacro" type

Gray plating + Green coating on the threads:

"Torquer" type

1. When replacing nuts and bolts, use only the same

type.

2. Tighten the nuts and bolts with a torque wrench to

the specifications provided in this manual.

3. Clean all thread ridges with a non-wire-type bristle

brush. Foreign matter in the threads may cause the

bolt to loosen.

4. Sections on this vehicle requiring the use of Dacro nuts

and bolts will be indicated by a in this manual.ProCarManuals.com

Description

The automatic transmission is a combination of a 3-element torque converter and a triple-shaft electronically controlled

automatic transmission which provides 4 speeds forward and 1 speed reverse. The entire unit is positioned in line with the

engine.

Torque Converter, Gears, and Clutches

The torque converter consists of a pump, turbine, and stator, assembled in a single unit.

They are connected to the engine crankshaft so they turn together as a unit as the engine turns.

Around the outside of the torque converter is a ring gear which meshes with the starter pinion when the engine is being

started. The entire torque converter assembly serves as a flywheel while transmitting power to the transmission main-

shaft. The transmission has three parallel shafts: the mainshaft, the countershaft, and the secondary shaft. The mainshaft

is in line with the engine crankshaft.

The mainshaft includes the 1st and 4th clutches, and gears for 3rd, 4th, reverse, and 1st (3rd gear is integral with the main-

shaft, while reverse gear is integral with 4th gear).

The countershaft includes the 1st-hold and 3rd clutches, and gears for 2nd, 3rd, 4th, reverse, 1st, and parking.

The secondary shaft includes the 2nd clutch and gears for 2nd and 3rd.

The 4th and reverse gears can be locked to the countershaft at its center, providing 4th gear or reverse, depending on

which way the selector is moved.

The gears on the mainshaft and secondary shaft are in constant mesh with those on the countershaft.

When certain combinations of gears in the transmission are engaged by clutches, power is transmitted from the mainshaft

to the countershaft to provide positions.

Electronic Control

The electronic control system consists of the Transmission Control Module (TCM), sensors, a linear solenoid, a shift switch,

and 4 solenoid valves. Shifting and lock-up are electronically controlled for comfortable driving under all conditions.

The TCM is located on the insulator center bulkhead, behind the driver's seat.

Hydraulic Control

The valve bodies include the main valve body, secondary valve body, servo body, regulator valve body, throttle valve

body, lock-up valve body, and the 2nd accumulator body.

They are bolted to the torque converter housing as an assembly.

The main valve body contains the manual valve, 1-2 shift valve, 2-3 shift valve, 3-4 shift valve, relief valve, one-way relief

valve, and oil pump gears.

The secondary valve body contains the 3-2 kick-down valve, clutch pressure control (CPC) valve, 2nd orifice control valve, 3rd

orifice control valve, modulator valve, 4th exhaust valve, servo control valve, 2nd exhaust valve, and 4-3 kick-down valve.

The servo body contains the accumulator pistons and servo valve. The throttle valve body includes the throttle valve B

which is bolted to the servo body.

The regulator valve body contains the pressure regulator valve, lock-up control valve, and cooler relief valve. Fluid from

the regulator passes through the manual valve to the various control valves.

The lock-up valve body contains the lock-up timing B valve and lock-up shift valve. The 2nd accumulator body contains

the accumulator pistons and limited slip differential relief valve.

The torque converter check valve is located in the torque converter housing, under the main valve body.

The 1st, 1st-hold, 3rd, and 4th clutches receive fluid from their respective feed pipes and the 2nd clutch receives fluid from

the internal hydraulic circuit.

Shift Control Mechanism

Input from various sensors located throughout the vehicle determines which shift control solenoid valve the TCM will acti-

vate. Activating a shift control solenoid valve changes modulator pressure, causing a shift valve to move. This pressurizes

a line to one of the clutches, engaging that clutch and its corresponding gear.

Lock-up Mechanism

In position and position in 2nd, 3rd, and 4th, pressurized fluid is drained from the back of the torque converter

through a fluid passage, causing the lock-up piston to be held against the torque converter cover. As this takes place, the

mainshaft rotates at the same speed as the engine crankshaft. Together with hydraulic control, the TCM optimizes the tim-

ing of the lock-up mechanism.

The lock-up valves control the range of lock-up according to lock-up control solenoid valves A and B, and throttle valve B.

When lock-up control solenoid valves A and B activate, modulator pressure changes. The lock-up control solenoid valves

A and B are mounted on the torque converter housing, and are controlled by the TCM.

(cont'd)ProCarManuals.com

• Whil e testing , b e carefu l o f th e rotatin g rea r wheels .
• Mak e sur e lift s ar e place d properl y (se e sectio n 1 ).
CAUTION :
• Befor e testing , b e sur e th e transmissio n flui d is fille d
to th e prope r level .
• War m u p th e engin e befor e testing .
1 . Rais e th e vehicl e (se e sectio n 1 ).
2 . War m u p th e engine , the n sto p th e engin e an d con -
nec t a tachometer .
3 . Connec t a pressur e gaug e t o eac h inspectio n hole .
18N-m(1.8kgf-m,13lbf-ft )
CAUTION: Connec t th e pressur e gaug e securely ;
b e sur e no t t o allo w dus t an d othe r foreig n parti -
cle s t o ente r th e inspectio n hole .
A/T OI L PRESSUR E A/ T OI L PRESSUR E
GAUG E SE T W/PANE L HOSE , 221 0 m m
07406-002040 0 07MA J - PY4011 A(4 Required )
A/ T LO W PRESSUR E A/ T OI L PRESSUR E
GAUG E W/PANE L HOS E ADAPTE R
0740 6 - 007030 0 07MA J - PY4012 0
( 4 Required )
4. Star t th e engine , an d measur e th e respectiv e pres -
sur e a s follows .
• Lin e Pressure/Clutc h Pressur e
• Clutc h Low/Hig h Pressur e
• Throttl e B Pressur e
5 . Instal l a ne w washe r an d th e sealin g bol t i n th e
inspectio n hole , an d tighte n to th e specifie d torque .
Torque : 1 8 N- m (1. 8 kgf-m , 1 3 Ibf-ft )
NOTE : D o no t reus e ol d aluminu m washers . •
Lin e Pressure/Clutc h Pressur e Measuremen t
1 . Allo w th e rea r wheel s t o rotat e freely .
2 . Ru n th e engin e a t 2,00 0 rpm .
3 . Shif t th e shif t leve r a s show n o n th e char t o n
th e nex t page .
4 . Measur e eac h clutc h pressure .
While testing , b e carefu l o f th e rotat -
in g rea r wheels .
Pressur e Testin g
ProCarManuals.com

System Description

Function and Operation

Steering Sensor

The steering sensor consists of a torque sensor, an

interface.

Torque Sensor

The torque sensor converts steering torque input and its

direction to voltage signals, in conjunction with the

interface.

A torsional force caused by steering operation is con-

verted to an axial movement of a slider core. A variable

differential transformer is installed around the slider

core.

Within the transformer are three coils, a primary coil on

the inside, and two secondary coils, one for right turns

and one for left turns.

Alternating current is passed through the primary coil

when the system is energized. The amount of mutual

induction from the primary coil to the secondary coils

changes depending on the position of the slider coil.

The input shaft and the slider are one piece. Rotation of

the shaft moves the slider in a circular direction. The

pinion is turned via the torsion bar. The slider core is

installed on the pinion shaft on grooves, and turns with

the pinion shaft.

When there is little resistance, the input shaft torsion

bar, pinion shaft, and the slider core turn together to the

same angle. The slider core does not move up/down.

When there is resistance on the input shaft (hard to steer situation), and the slider pin is turned at an angle by the steering

wheel, the torsion bar is twisted due to the resistance. Accordingly, the pinion shaft turns at a smaller angle. The differ-

ence in the turning angles changes the position of the slider pin in the groove, forcing the slider core upward or down-

ward, depending on the direction of the direction of the turn.ProCarManuals.com

Self-Diagnosis Function

The EPS control unit monitors the system inputs and outputs, and the driving current of the motor. If there is a problem in

the system, the control unit turns the system off by actuating the relay. Power assist stops and normal manual steering

operation resumes. The control unit also turns the EPS indicator light on to alert the driver, and memorizes the problem in

the form of a code. Connecting the terminals of the service check connector with the SCS service connector (special tool)

enables the EPS indicator light to blink the problem code when the ignition switch is turned on (II).

Unloader Control

If the steering wheel is turned fully and held in the full-lock position, the steering torque reaches the maximum point, and

an over-current flows to the motor. The control unit detects this and reduces the current flow to the motor.

Average Moving Current Control

The electric current flow to the motor is estimated from the current values detected by the current sensor, and the average

current is obtained at two second intervals. The motor driving current is suppressed when the average current value

exceeds a predetermined marginal value. The control unit regulates the motor current during continuous loading to sup-

press any excessive temperature rise in the motor.ProCarManuals.com

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

6. Install the new self-locking nuts on the top of the

damper assembly.

STRUT BRACE SELF-LOCKING NUT 10 x 1.25 mm

Replace.

53 N-m (5.4 kgf-m, 39 Ibf-ft)

Corrosion resistant bolt/nut

7. Tighten the damper mounting nut to the specified

torque.

8. Secure the damper assembly to the frame with the

self-locking nuts.

9. Install the strut brace (NSX-T model only).

10. Install the rear hatch glass trim.

TAPPING SCREW REAR HATCH GLASS

11. Install the engine cover support rod onto the strut

brace.

12. Install the rear wheels.ProCarManuals.com

Inspection/Replacement (cont'd )
Front Brak e Pad s
6. Clea n th e calipe r thoroughly ; remov e an y rust , an d
chec k fo r groove s an d cracks .
7 . Instal l th e pa d retainers . 11
. Pus h i n th e piston s s o tha t th e calipe r wil l fi t ove r
th e brak e pads .
12 . Se t th e calipe r dow n int o position , the n instal l th e
brak e hos e mountin g bolt s an d th e calipe r mount -
in g bolts . Tighte n th e bolt s t o th e specifie d torque .
8 . Appl y Molykot e M7 7 t o bot h side s o f calipe r bracke t
an d th e bac k o f th e pads . Wip e exces s greas e of f
the shim .
9. Instal l th e brak e pads .
• Whe n reusin g th e pads , alway s reinstal l th e
brak e pad s i n thei r origina l position s t o preven t
los s o f brakin g efficiency .
• Contaminate d brak e disc s o r pad s reduc e stop -
pin g ability . Kee p greas e of f th e brak e disc s o r
pads .
NOTE :
• Instal l th e inne r pa d wit h it s wea r indicator fac-
in g upward .
• Appl y Molykot e M7 7 t o th e shim s (se e pag e
19-6 ). Wip e exces s greas e of f th e shims .
10 . Instal l th e brak e pa d shim s correctly . 13
. Depres s th e brak e peda l severa l time s t o mak e sur e
th e brake s work , the n test-driv e th e vehicle .
NOTE: Engagemen t o f th e brak e ma y requir e a
greate r peda l strok e immediatel y afte r th e brak e
pad s hav e bee n replace d a s a set . Severa l applica -
tion s of the brak e peda l wil l restor e th e norma l
peda l stroke .
14 . Instal l th e fron t wheel s an d toqu e th e whee l nuts .
NOTE : Clea n th e matin g surfac e o f th e whee l an d
hu b befor e installin g th e wheel .
ProCarManuals.com

Inspection/Replacement (cont'd)
Rear Brake Pads

11. Install and tighten the two caliper mounting bolts.

12. Insert the cable through the arm, and connect the

cable to the lever with the clevis pin and new lock

pin. Install the new cable clip securely.

13. Install the caliper shield.

14. Depress the brake pedal several times to make sure

the brakes work, then test-drive the vehicle.

NOTE: Engagement of the brake may require a

greater pedal stroke immediately after the brake

pads have been replaced as a set. Several applica-

tions of the brake pedal will restore the normal

pedal stroke.

15. Install the rear wheels and torque the wheel nuts.

NOTE: Clean the mating surfaces of the wheel and

hub before installing the wheel.ProCarManuals.com