1991 ACURA NSX Service Repair Manual

System Description

Suspension Composition

Outline

Double wishbone independent suspension has been selected for each of the four wheels. This eliminates damper friction

along the steering axis, and permits suspension geometry that takes full advantage of the performance potential of the

wide, low aspect ratio tires. The double wishbone design also allows the use of aerodynamically-efficient and

aesthetically pleasing low fender lines.

The knuckles and the suspension arms are manufactured from lightweight, high-strength aluminum alloys. This gives a

notable reduction in unsprung weight which results in increased traction and improved ride. It also allows the individual

suspension components to be designed in detail for maximum strength and rigidity.

FRONT

UPPER

CONTROL

ARM
KNUCKLE

STABILIZER
REAR

UPPER

CONTROL

ARM
STABILIZER

KNUCKLE

LOWER CONTROL ARM

LOWER CONTROL ARM

To further increase suspension link rigidity, and to obtain optimum knuckle geometry, the knuckles and ball joints are

contained within the wheel profile. At each corner of the car, the individual suspension system is attached to the alumi-

num stressed skin chassis by a cast aluminum sub-frame. This design further reduces overall weight, and ensures that

suspension loads are fed into the chassis at the most efficient points, and in the most efficient directions.

A large front caster angle combined with small trail distance improves straight-line stability and response without caus-

ing heavy steering effort.

FRONT
REAR

SUB-FRAME

SUB-FRAMEProCarManuals.com

(Front Compliance Mechanism)

To avoid the usual compromise between ride quality and handling characteristics, a pivot-type "compliance mechanism"

has been designed as an integral part of the front suspension. When one of the front wheels is subjected to a rearward

movement by an uneven road surface or by heavy braking, the load produced has two separate effects. As with any

suspension system, the load acts in the vertical direction to compress the suspension spring and reduce the ride height.

On the NSX/NSX-T the load also acts through both the upper and lower control arms to twist the compliance pivot. This

allows the wheel to move rearward by a controlled amount, thus absorbing energy. The result is an outstanding ride

quality with only minimal changes to track width and wheel geometry. In cornering, the compliance pivot does not come

into play, and the lateral suspension stiffness required for maximum roadholding and optimum control response is main-

tained.

COMPLIANCE

PIVOT

TOP VIEW

(Rear Toe Control Arm)

Many conventional passenger-car independent rear suspension systems are subject to undesirable changes in toe-in

angle with wheel movement. This results in instability both in cornering and in acceleration. In the NSX/NSX-T, the de-

sign and pivot locations of the rear toe control arm produce a slight controlled increase in toe-in during bump travel. As

a result, the NSX/NSX-T is extremely stable under heavy cornering loads and over bumpy road surfaces.

TOP VIEW

TOE CONTROL ARM
COMPLIANCE

PIVOTProCarManuals.com

Wheel Alignment

Height

NSX/NSX-T four wheel alignment requires the use of equipment designed specifically for four wheel independent

suspensions and capable of immediate feedback.

NOTE: For proper inspection/adjustment of the wheel alignment, check and adjust the following before checking

the alignment.

• Check that the suspension is not modified.

• Check the tire size and tire pressure.

• Check the runout of the wheels and tires.

• Check the suspension ball joints. (Hold a wheel with your hands, then move the wheel up and down and right

and left to check for wobbling.)

• Check the height of each suspension (see below).

Standard value

Front:

Ground clearance to the center of the lower

control arm bolt
Rear:

Ground clearance to the center of the toe con-

trol arm bolt

Height inspection:

• Before checking for the height, bounce the car up and down several times before measuring.

• Check the height with the car empty, parked on a level surface, with properly inflated tires (tread wear indicators must

not be showing). If the height is out of specification, load or unload the car as necessary.ProCarManuals.com

Front Wheel Alignment Adjusting Procedure

Adjustment

NOTE: NSX/NSX-T four wheel alignment requires the use of equipment designed specifically for four wheel independent

suspensions and capable of immediate feedback.

The NSX/NSX-T suspension can be adjusted for camber, caster (front only), and toe. However, because each of them

relates to the other, the camber changes when the toe is adjusted for example. Therefore, the total adjustment of the

front/rear wheel alignment is required whenever one of the elements (camber, caster, or toe) is adjusted.

Front wheel alignment adjusting procedure

Check tire pressure on both sides.

Check the ride height on both sides.

Measure and adjust both camber and toe of the

left side.

Measure and adjust both camber and toe of the

right side.

Adjust caster on both sides.

Measure and readjust both camber and toe of

the left side.

Measure and readjust both camber and toe of

the right side.
CASTER

TOP VIEW
CAMBERProCarManuals.com

Wheel Alignmen t
Front Whee l Alignmen t Adjustmen t Procedur e
NOTE:
• NSX/NSX- T fou r whee l alignmen t require s th e us e o f
equipmen t designe d specificall y fo r fou r whee l in -
dependen t suspension s an d capabl e o f immediat e
feedback.
• Th e rid e heigh t i s ver y importan t fo r settin g th e align -
ment . Fo r ever y 1 0 m m (0. 4 in ) o f chang e i n th e
fron t rid e height , th e cambe r wil l chang e approx -
imatel y 1 0 minutes .
• Th e fron t alignmen t setting s o n th e NS X ar e
interactive .
• A sligh t chang e i n to e wil l dramaticall y chang e th e
camber .
• Alway s inspec t an d adjus t th e fron t whee l alignmen t
with th e steerin g whee l i n th e straigh t ahea d
position .
1 . Driv e th e ca r o n th e alignmen t rack .
2 . Chec k th e tir e pressur e an d rid e heigh t (se e pag e
18-6 ).
3 . Cente r th e steerin g whee l i n th e straigh t ahea d
position , an d loc k it i n plac e wit h th e steerin g lock .
4 . Se t th e alignmen t equipmen t followin g th e
manufacturer' s instructions .
5 . Measur e an d adjus t th e cambe r an d to e o n th e lef t
side , the n measur e an d adjus t th e righ t side .
Toe:
— Loose n th e locknut , an d tur n th e righ t an d lef t
tie-rod s t o adjus t th e fron t toe .
LOCKNU T44 N- m(4.4 kg-m , 3 2 Ib-ft )TIE-RO D
Camber :
— Loose n th e self-lockin g nu t o n th e fron t lowe r
contro l ar m adjustin g point , an d adjus t th e
cambe r b y turnin g th e adjustin g cam .
SELF-LOCKIN G NU TReplace .125 N- m(12. 5 kg-m , 9 0 Ib-ft )
Corrosio n resistan t bolt/nu t
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6. Measure the caster on the both sides, and adjust the

caster to specifications.

Caster:

• Loosen the pivot adjuster mounting nuts (self-

locking nuts) under the compliance pivot, and

adjust the caster by turning the adjusting cam.

SELF-LOCKING

NUT

Replace.

85 N-m

(8.5 kg-m, 61 Ib-ft)
ADJUSTING CAM

Corrosion resistant bolt/nut

7. Remeasure and, if necessary, adjust the camber and

toe on the left side first, then the right side.

Front Specifications

Toe-out: 3.5 ± 1.0 mm (0.14 ± 0.04 in)

Camber: -0° 20' ± 30'

Caster: 8° 00' ± 45'ProCarManuals.com

Wheel Alignmen t
Front Turnin g Angl e Inspectio n
NOTE:
• Plac e a ca r o n a leve l surfac e befor e inspection .
• Releas e th e parkin g brak e an d b e sur e tha t th e ca r i s
empty .
• Chec k tha t th e suspension s ar e a t th e standar d
heigh t (se e pag e 18-6 ).
1 . Tur n th e steerin g whee l full y t o th e righ t an d lef t
whil e applyin g th e brake , an d measur e th e turnin g
angl e o f bot h wheels .
Turnin g angle : Inward : 33°0 6 ± 2°
Outward : 26°3 4 (Referenc e value )
2 . I f th e measurement s ar e no t withi n th e specifica -
tions o r i f th e inwar d turnin g angle s diffe r betwee n
the righ t an d left , chec k th e to e an d adjus t accor -
dingl y (se e pag e 18-8 ).
3 . I f th e to e adjustmen t i s withi n specifications , an d
turnin g angl e i s stil l off , chec k fo r ben t o r damage d
suspensio n components .
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Rear Whee l Alignmen t Adjustin g Procedur e
Rear whee l alignmen t adjustin g procedur e
Chec k tir e pressur e o n bot h sides .
Chec k th e rid e heigh t o n bot h sides .
Adjus t bot h cambe r an d to e o f th e lef t side .
Adjus t bot h cambe r an d to e o f th e righ t side .
TOP VIE W
CAMBE R
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