ACURA NSX 1991 Service Repair Manual

Change Holder Assembly, Shift Fork

Clearance Inspection

1. Measure the clearance between the shift piece and

shift arm.

Standard: 0.05—0.25 mm

(0.002-0.010
in)

Service Limit: 0.5 mm (0.020 in)

SHIFT ARM
SHIFT PIECE

2. If the clearance exceeds the service limit, measure

the width of the shift arm.

Standard:
12.9-13.0
mm
(0.508-0.512
in)

SHIFT ARM

If the width of the shift arm is less than the stan-

dard, replace the shift arm with a new one.

If the width of the shift arm is within the standard,

replace the shift piece with a new one.
3. Measure the clearance between the interlock and

select arm.

Standard:
0.03-0.15
mm
(0.001
-
0.006
in)

INTERLOCK

SELECT ARM

4. If the clearance exceeds the standard, measure the

width of the interlock finger.

Standard: 11.95 - 12.00 mm

(0.470-0.472 in)

INTERLOCK

If the width of the interlock is less than the stan-

dard, replace the interlock with a new one.

If the width of the interlock is within the standard,

replace the select arm with a new one.ProCarManuals.com

5. Measure the clearance between the shift fork, the

5th/reverse shift piece and shift piece.

Standard:
0.2-0.5
mm

(0.008-0.020
in)

Service Limit: 0.6 mm (0.024 in)

1ST/2ND SHIFT FORK

5TH/REVERSE

SHIFT PIECE

6. If the
clearance exceeds
the
service
limit,
measure

the width of the shift piece.

Standard: 11.9 - 12.0 mm (0.469-0.472 in)

SHIFT PIECE

If the width of the shift piece is less than the stan-

dard, replace the shift piece with a new one.

If the width of the shift piece is within the standard,

replace the 5th/reverse shift piece or shift forks

with a new one.
3RD/4TH

SHIFT FORK

SHIFT PIECEProCarManuals.com

Shift Fork, Synchro

Sleeve

Clearance Inspection

1. Measure the clearance between each shift fork and

its matching synchro sleeve.

Standard:
0.45-0.65
mm

(0.018-0.026 in)

Service Limit: 1.0 mm (0.039 in)

SYNCHRO

SLEEVE

SHIFT FORK

2. If the clearance exceeds the service limit, measure

the width of the shift fork fingers.

Standard:

1st/2nd
Shift
Fork:
8.9-9.0
mm

(0.350-0.354 in)

3rd/4th
Shift
Fork:
7.4-7.5
mm

(0.291 - 0.295 in)

5th Shift Fork: 6.4—6.5 mm

(0.252-0.256 in)

SHIFT FORK

If the width of the shift fork fingers is less than the

standard, replace the shift fork with a new one.

If the width of the shift fork fingers is within the

standard, replace the synchro sleeve with a new

one.

NOTE: The synchro sleeve and synchro hub

should be replaced as a set.ProCarManuals.com

Mainshaft Assembly

Clearance Inspection

1. Measure the clearance between 2nd and 3rd gears.

Standard: 0.06 — 0.21 mm

(0.002-0.008
in)

Service Limit: 0.3 mm (0.012 in)

2ND GEAR

3RD GEAR

2. If the clearance exceeds the service limit, measure

the thickness of 3rd gear.

Standard: 35.92 — 35.97 mm

(1.414-1.416 in)

Service Limit: 35.80 mm (1.409 in)

3RD GEAR

If the thickness of 3rd gear is less than the service

limit, replace 3rd gear with a new one.

If the thickness of 3rd gear is within the service

limit, replace the 3rd/4th synchro hub with a new

one.
3. Measure the clearance between 4th gear and the

spacer collar.

Standard: 0.06—0.21 mm

(0.002-0.008
in)

Service Limit: 0.3 mm (0.012 in)

4TH GEAR

5TH GEAR

4. If the clearance exceeds the service limit, measure

distance on the spacer collar.

Standard: 29.53 — 29.58 mm

(1.163-1.165 in)

Service Limit: 29.51 mm (1.162 in)

SPACER

COLLAR
4TH GEAR

"SIDE

5. If distance is less than the service limit, replace

the spacer collar with a new one.

If
distance
is
within
the
service
limit,
measure

the thickness of 4th gear.

Standard: 35.92-35.97 mm

(1.414-1.416 in)

Service Limit: 35.80 mm (1.409 in)

If the thickness of 4th gear is less than the service

limit,
replace
4th
gear
with
a new
one.

If the thickness of 4th gear is within the service

limit, replace the 3rd/4th synchro hub with a new

one.
4TH

GEARProCarManuals.com

6. Measure the clearance between the spacer collar

and 5th gear.

Standard: 0.06—0.21 mm

(0.002-0.008
in)

Service Limit: 0.3 mm (0.012 in)

4TH GEAR

5TH GEAR

7. If the clearance exceeds the service limit, measure

distance on the spacer collar.

Standard: 28.53—28.58 mm

(1.123-1.125 in)

Service Limit: 28.51 mm (1.122 in)

5TH GEAR

SIDE
SPACER

COLLAR

8. If distance is less than the service limit, replace

the spacer collar with a new one.

If distance is within the service limit, measure

thickness of 5th gear.

Standard: 34.92-34.97 mm

(1.375-1.377 in)

Service Limit: 34.80 mm (1.370 in)

5TH GEAR

If the thickness of 5th gear is less than the service

limit, replace 5th gear with a new one.

If the thickness of 5th gear is within the service

limit, replace the 5th synchro hub with a new one.ProCarManuals.com

Shift Fork Assembly

Disassembly/Reassembly

NOTE:

• Be careful not to lose the 5th shift fork steel ball.

• Install the spring pins so their grooves are 180° apart.

Prior to reassembling, clean all the parts in solvent, dry them, and apply lubricant to any contact surfaces.

Disassembly: Remove the 3 mm spring pin and 5 mm spring pin.

Reassembly: Install the 5 mm spring pin first, then install the 3 mm spring pin.

5TH/REVERSE SHIFT

FORK SHAFT
3RD/4TH SHIFT FORK

SHAFT COLLAR

1ST/2ND SHIFT

FORK SHAFT

5TH SHIFT FORK

SPRING WASHER

8 x 1.0 mm

SPECIAL BOLT

32 N-m (3.2 kg-m, 23 Ib-ft)
3RD/4TH SHIFT FORK

3RD/4TH SHIFT

FORK SHAFT

5 x 25 mm

SPRING PIN

Replace.
1ST/2ND SHIFT FORK

3 x 25 mm

SPRING PIN

Replace.

5 x 25 mm

SPRING PIN

Replace.

Drive to the

surface end.
5TH/REVERSE

SHIFT PIECE

3 x 25 mm

SPRING PIN

Replace.
STEEL

BALL (5/16 in)ProCarManuals.com

Mainshaft Assembl y
Index
NOTE : Th e 3rd/4t h an d 5t h synchr o hub s ar e installe d wit h a press .
Prior t o reassembling , clea n al l th e part s i n solvent , dr y them , an d appl y lubrican t t o an y contac t surfaces .
The 3rd/4t h an d 5t h synchr o hubs , however , shoul d b e installe d wit h a pres s befor e lubricatin g them .
3RD/4T H SYNCHR O HU B
SYNCHR O SPRIN G
SYNCHR O RIN G
Inspection , pag e 13-3 5
3RD GEA R
Measurement , pag e
13-24
43 x 49 x 29. 5 mmNEEDL E BEARING SInspect fo r wea r an d operatio n
MAINSHAF TInspection, pag e 13-2 6
BALL BEARIN GInspect fo r wea r an d operation .
BALL BEARIN GInspect fo r wea r an d operation .
5TH SYNCHR O SLEEV E
Inspection , pag e 13-3 6
5TH SYNCHRO HUB
SYNCHR O SPRIN G
SYNCHRO RINGInspection , pag e 13-3 5
5T H GEA R
Measurement , pag e 13-2 5
42 x 47 x 29 m mNEEDL E BEARIN GInspect fo r wea r an d operation .
SPACER COLLA R
Inspection , pag e 13-2 4
4T H GEA R
Measurement , pag e 13-2 4
SYNCHR O RIN G
Inspection , pag e 13-3 5
SYNCHR O SPRIN G
3RD/4T H SYNCHR O SLEEV E
Inspection , pag e 13-3 6
STOPPE R
ProCarManuals.com

Disassembly

1. Remove the ball bearing using a bearing puller as

shown.

Clutch housing side:

Transmission housing side:
BEARING PULLER

(Commercially

available)

BALL BEARING

BEARING

SEPARATOR,

0-4 1/2 in.

(Commercially

available)

BEARING PULLER

(Commercially

available)

BALL BEARING

BEARING

SEPARATOR,

0-4 1/2 in.

(Commercially

available)ProCarManuals.com

Mainshaft Assembly

Disassembly

CAUTION: Remove the synchro hubs using a press and

steel blocks as shown. Use of a jaw-type puller can

damage the gear teeth.

2. Support 5th gear on steel blocks as shown, and

press the shaft out of the 5th synchro hub.

ATTACHMENT
PRESS

5TH SYNCHRO HUB

5TH GEAR

3. In the same manner as above, support the 3rd gear

on steel blocks, and press the shaft out of the

3rd/4th synchro hub.

PRESS

ATTACHMENT

3RD/4TH SYNCHRO HUB

3RD GEARProCarManuals.com

Mainshaft Assembly
Inspectio n
1. Inspec t th e gea r surfac e an d bearin g surfac e fo r
wea r an d damage , the n measur e th e mainshaf t a t
point s A , B , an d C .
Standard :
A (Bal l bearin g surface) : 32.002—32.01 8 m m
(1.2599-1.260 5 in )
B (Needl e bearin g surface) : 42.984—43.00 0 m m
(1.6923-1.692 9 in )
C (Bal l bearin g surface) : 30.984-31.00 0 mm
(1.2198-1.220 5 in )
Servic e limit :
A: 31.95 0 m m (1.257 9 in )
B: 42.93 0 m m (1.690 2 in )
C: 30.93 0 m m (1.217 7 in )
Inspec t oi l passage s fo r clogging .
Inspect fo r wea r an d damage .
If an y par t o f th e mainshaf t i s les s tha n th e servic e
limit, replac e it wit h a ne w one .
ProCarManuals.com