1991 ACURA NSX Service Repair Manual

Front Calipe r
Disassembl y
• Neve r us e a n ai r hos e o r dr y brus h t o clea n brak e
assemblies .
• Us e a n OSHA-approve d vacuu m cleane r t o avoi d
breathin g brak e dust .
CAUTION :
• D o no t spil l brak e flui d o n th e car ; i t ma y damag e th e
paint ; i f brak e flui d doe s contac t th e paint , was h i t
of f immediatel y wit h water .
• T o preven t spills , cove r th e hos e joint s wit h rag s o r
sho p towels .
• Clea n al l part s i n brak e flui d an d ai r dry ; blo w ou t al l
passage s wit h compresse d air .
1 . Remov e th e banj o bolt , an d disconnec t th e brak e
hos e fro m th e caliper .
2. Remov e th e calipe r mountin g bolts , the n remov e
the caliper .
3 . Remov e th e pa d sprin g fro m th e calipe r body . 4
. I f necessary , appl y compresse d ai r t o th e calipe r
fluid inle t t o ge t th e piston s out . Plac e a sho p ra g o r
woode n bloc k a s show n t o cushio n th e piston s
when ther e ar e expelled . Us e lo w pressur e ai r i n shor t
spurts .
• D o no t plac e you r finger s i n fron t o f th e piston .
• D o no t us e hig h ai r pressure ; us e a n OSHA -
approve d 3 0 PS I nozzle .
5 . Remov e th e pisto n boot s an d pisto n seals .
CAUTION : Tak e car e no t t o damag e th e cylinders .
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Reassembly
CAUTION:
• Befor e reassembling , chec k tha t al l part s ar e fre e o f
dus t an d othe r foreig n particles .
• Replac e part s wit h ne w one s wheneve r specifie d t o
do so .
• Us e onl y clea n DOT 3 o r 4 brak e fluid .
• Mak e sur e n o dir t o r othe r foreig n matte r i s allowe d
t o contaminat e th e brak e fluid .
• D o no t spil l brak e flui d o n th e car ; i t ma y damag e th e
paint ; i f brak e flui d doe s contac t th e paint , was h i t
of f immediatel y wit h water .
1. Clea n th e piston s an d calipe r bore s wit h brak e fluid ,
and inspec t fo r wea r an d damage .
2. Appl y silicon e greas e t o ne w pisto n seals , the n in -
stal l th e pisto n seal s i n th e cylinde r grooves .
3. Appl y silicon e greas e t o ne w pisto n boots , the n in -
stal l th e pisto n boot s in th e cylinde r grooves .
4. Lubricat e th e calipe r cylinder s an d piston s wit h
brak e fluid , the n instal l th e piston s i n th e cylinder s
with th e dishe d en d facin g in .
5. Reinstal l th e calipe r i n th e revers e orde r o f removal .
6 . Fil l th e brak e reservoi r up , an d blee d th e brak e
system (se e pag e 19-10 ).
NOTE : A ne w dis c shoul d b e refinishe d i f it s
runou t i s greate r tha n 0.1 0 m m (0.00 4 in) .
Fron t Brak e Dis c
Run-Ou t Inspectio n
1. Rais e eac h sid e o f th e car , an d suppor t i t o n safet y
stand (se e pag e 1-9 throug h 1-11 ). Remov e th e fron t
wheels .
2. Remov e th e brak e dis c pad s (se e pag e 19-6 ).
3 . Inspec t th e dis c surfac e fo r crack s an d rust . Clea n
the dis c thoroughly , an d remov e al l rust .
4. Us e suitabl e nut s (1 2 x 1. 5 mm ) an d plai n washer s
to hol d th e dis c securel y agains t th e hub , the n
moun t a dia l indicato r a s shown .
Brake Dis c Runout :
Service Limit : 0.1 0 m m (0.00 4 in )
5. I f th e dis c i s beyon d th e servic e limit , refinis h it .
Max . Refinishin g Limit : 26. 0 m m (1.0 2 in )
Front Caliper
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Front Brak e Dis c
Thicknes s an d Parallelis m
Inspectio n
1. Rais e eac h sid e o f th e car , an d suppor t i t o n safet y
stands (se e pag e 1-9 throug h 1-11 ). Remov e th e fron t
wheels .
2 . Remov e th e brak e dis c pad s (se e pag e 19-6 ).
3 . Usin g a micrometer , measur e dis c thicknes s a t
eigh t points , approximatel y 45 ° apar t an d 1 0 m m
(0. 4 in ) i n fro m th e oute r edg e o f th e disc .
Brak e dis c thickness :
Standard : 28. 0 m m (1.1 0 in ) max .
Servic e Limit : 26. 0 m m (1.0 2 in )
Brak e Dis c Parallelism :
Th e differenc e betwee n an y thicknes s mea -
surement s shoul d no t b e mor e tha n 0.01 5 m m
(0.000 6 in) .
4. I f th e dis c i s beyon d th e limit s fo r parallelism ,
refinis h it .
Max . Refinishin g Limit : 26.0 mm (1.0 2 in )
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Master Cylinde r an d Brak e Booste r
Index/Torqu e
BRAKE BOOSTE R
D o no t disassemble .
Tests , pag e 19-1 4
Pushro d Clearanc e Adjustment , pag e 19-1 5
MASTE R CYLINDE R
Inspection, pag e 19-1 3
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Master Cylinder

Inspection

CAUTION:

• Be careful not to bend or damage the brake pipes when removing the master cylinder.

• Do not spill brake fluid on the car; it may damage the paint; if brake fluid does contact the paint, wash it off immediate-

ly with water.

• To prevent spills, cover the hose joints with rags or shop towels.

• Before reassembling, check that all parts are free of dust and other foreign particles.

• Do not try to disassemble the master cylinder assembly. Replace the master cylinder assembly with a new part if

necessary.

• Make sure no dirt or other foreign matter is allowed to contaminate the brake fluid.

• Do not reuse the drained fluid. Use only clean DOT3 or 4 brake fluid.

• When connecting the brake pipes, make sure that there is no interference between the brake pipes and other parts.ProCarManuals.com

Brake Booste r
Tests
Functiona l Tes t
1. Wit h th e engin e stopped , depres s th e brak e peda l
severa l time s t o deplet e th e vacuu m reservoir , the n
depres s th e peda l har d an d hol d i t fo r 1 5 seconds .
I f th e peda l sinks , eithe r th e maste r cylinde r i s
bypassin g internally , o r th e brak e syste m (maste r
cylinder , lines , modulator , proportionin g valve , o r
calipers ) ar e leaking .
2 . Star t th e engin e wit h th e peda l depressed . I f th e pe -
da l sink s slightly , th e vacuu m booste r i s operatin g
normally , i f th e peda l heigh t doe s no t vary , th e
booste r o r chec k valv e i s faulty .
3 . Wit h th e engin e running , depres s th e brak e peda l
lightly . Appl y jus t enoug h pressur e t o hol d bac k au -
tomati c transmissio n creep . I f th e brak e peda l sink s
mor e tha n 2 5 m m (1. 0 in. ) i n thre e minutes , th e
maste r cylinde r i s faulty . A sligh t chang e i n peda l
heigh t whe n th e A/ C compresso r cycle s o n an d of f
i f normal . (Th e A/ C compresso r loa d change s th e
vacuu m availabl e t o th e booster. )
Leak Tes t
1. Depres s th e brak e peda l wit h th e engin e running ,
the n sto p th e engine . I f th e peda l heigh t doe s no t
var y whil e depresse d fo r 3 0 seconds , th e vacuu m
booste r i s OK . I f th e peda l rises , th e booste r i s faulty .
2 . Wit h th e engin e stopped , depres s th e brak e peda l
severa l time s usin g norma l pressure . Whe n th e pe -
da l i s firs t depressed , i t shoul d b e low . O n consecu -
tiv e applications , th e peda l heigh t shoul d graduall y
rise . I f th e peda l positio n doe s no t vary , chec k th e
booste r chec k valve .
Booste r Chec k Valv e Tes t
1. Disconnec t th e brak e booste r vacuu m hos e a t th e
booste r o r a t th e booste r sid e o f th e valve .
2 . Star t th e engin e an d le t i t idle . Ther e shoul d b e vacu -
um . I f n o vacuu m is available , th e chec k valv e is no t
workin g properly . Replac e th e chec k valv e an d
retest .
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Pushrod Clearanc e Adjustmen t
NOTE: Maste r cylinde r pushrod-to-pisto n clearanc e
mus t b e checke d an d adjustment s made , i f necessary ,
befor e installin g maste r cylinder .
1 . Se t th e specia l too l o n th e maste r cylinde r body ;
pus h i n th e cente r shaf t unti l th e to p o f i t contact s
wit h th e en d o f th e secondar y pisto n b y turnin g th e
adjustin g nut .
07JAG-SD4010 0
2. Withou t disturbin g th e cente r shaft' s position , in -
stal l th e specia l too l upsid e dow n o n th e brak e
booster .
3 . Instal l th e maste r cylinde r nut s an d tighte n t o th e
specifie d torque .
4 . Connec t th e brak e booste r in-lin e wit h a vacuu m
gaug e 0-76 0 m m H g ( 0 -3 0 i n Hg ) t o th e
booster' s engin e vacuu m supply , an d maintai n a
engin e spee d tha t wil l delive r 50 0 m m H g (2 0 i n
Hg ) vacuum .
5 . Wit h a feele r gauge , measur e th e clearanc e be -
twee n th e gaug e bod y an d th e adjustin g nu t a s
shown . NOTE
: I f th e clearanc e betwee n th e gaug e bod y
an d adjustin g nu t i s 0. 4 m m (0.0 2 in) , th e pushrod -
to-pisto n clearanc e i s 0 mm . However , i f th e
clearanc e betwee n th e gaug e bod y an d adjustin g
nu t i s O mm , th e pushrod-to-pisto n clearanc e is 0. 4
m m (0.0 2 in ) o r more . Therefore , i t mus t b e ad -
juste d an d rechecked .
6 . I f clearanc e is incorrect , loose n th e sta r locknu t an d
turn th e adjuste r i n o r ou t t o adjust .
NOTE:
• Adjus t th e clearanc e whil e th e specifie d vacuu m
i s applie d t o th e brak e booster .
• Hol d th e clevi s whil e adjusting .
7 . Tighte n th e sta r locknu t securely .
8 . Remov e th e specia l tool , an d instal l a ne w maste r
cylinde r ro d sea l i n th e brak e booster .
07JAG-SD40100
9. Adjus t th e pushro d lengt h a s show n i f th e booste r
i s removed .
10 . Instal l th e maste r cylinde r (se e pag e 19-12 ).
11 . Afte r installation , perfor m th e followin g inspec -
tion s an d adjus t i f necessary .
• Brak e peda l heigh t (se e pag e 19-4 ).
• Brak e peda l fre e pla y (se e pag e 19-4 ).
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Rear Brakes

Torque/Inspection

• Never use an air hose or dry brush to clean brake

assemblies.

• Use an OSHA-approved vacuum cleaner to avoid

breathing brake dust.

• Contaminated brake discs or pads reduce stopping

ability.
CAUTION:

• Do not spill brake fluid on the car; it may damage

the paint; if brake fluid does contact the paint,

wash it off immediately with water.

• To prevent spills, cover the hose joints with rags

or shop towels.

• Clean all parts in brake fluid and air dry; blow out

all passages with compressed air.

• Before reassembling, check that all parts are

free of dust and other foreign particles.

• Replace parts with new ones whenever

specified to do so.

• Make sure no dirt or other foreign matter is

allowed to contaminate the brake fluid.

• Do not reuse the drained fluid. Use only clean

DOT3 or 4 brake fluid.

NOTE:

• Coat piston, piston seal, and caliper bore with

clean brake fluid.

• Replace all rubber parts with new ones

whenever disassembled.ProCarManuals.com