1991 ACURA NSX Service Repair Manual

Description

Hydraulic Control (cont'd)

Secondary Valve Body

The secondary valve body is also mounted on the main valve body with the 3-2 kick-down valve, CPC valve, 2nd orifice

control valve, 3rd orifice control valve, modulator valve, 4th exhaust valve, 2nd exhaust valve, servo control valve and

4-3 kick-down valve built in.

Primarily, it regulates shift valve operation timing and clutch pressure for shock reduction during shifting.

MODULATOR VALVE

4TH EXHAUST VALVE

SERVO CONTROL VALVE

3-2 KICK-DOWN

VALVE

SECONDARY VALVE BODY

4-3 KICK-DOWN VALVE

2ND EXHAUST VALVE
CPC VALVE
2ND ORIFICE

CONTROL VALVE
3RD ORIFICE CONTROL

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Modulator Valve

The modulator valve maintains line pressure from the regulator that is supplied to shift control solenoid valves A/B and

lock-up control solenoid valves A/B, thus maintaining accurate shift and lock-up characteristics.

MODULATOR VALVE

2nd Orifice Control Valve

For smooth shifting between the 2nd and 3rd gear, the open pressure on the 2nd gear side is relieved through a fixed

orifice. The valve also moves to equalize pressure differences between the 2nd and 3rd gear.

2nd Exhaust Valve

The 2nd exhaust valve is installed to release 2nd clutch pressure quickly when shifting from the range at which hydraulic

pressure is applied to the 2nd clutch to the position.

2ND ORIFICE CONTROL VALVE

(cont'd)
2ND EXHAUST VALVEProCarManuals.com

Description
Hydraulic Control (cont'd)
Servo Body/2nd Accumulator Body The servo body is mounted on the secondary valve body with the servo valve, 1st accumulator piston, 3rd accumulator
piston and 4th accumulator piston built in. The primary function of the servo body is forward and reverse switching and

control.

The 2nd accumulator body is mounted on the torque converter housing with the 1st-hold accumulator, 2nd accumulator
and limited slip differential relief valve built in.
1ST-HOLD ACCUMULATOR PISTON
2ND ACCUMULATOR PISTON LIMITED SLIP DIFFERENTIAL

RELIEF VALVE

2ND ACCUMULATOR BODY

SERVO VALVE
1ST ACCUMULATOR PISTON
ATF STRAINER

Limited Slip Differential Relief Valve

When the resistance of oil flow inside the limited slip differential becomes large, the limited slip differential relief valve is
opened, and oil is sent to the ATF cooler and cooled. 4TH ACCUMULATOR

PISTON

3RD ACCUMULATOR

PISTON

SERVO BODYProCarManuals.com

Lock-up Valve Body

The lock-up valve body is mounted on the regulator valve body with the lock-up shift valve and lock-up timing B valve

built in.

The capacity of the lock-up clutch is controlled by the lock-up valve body.

LOCK-UP SHIFT VALVE

LOCK-UP VALVE

BODY

LOCK-UP TIMING B VALVEProCarManuals.com

Description

Hydraulic Flow

General of Hydraulic Pressure

Oil Pump
Regulator Valve

Distribution of Hydrualic Pressure

Manual Valve

Throttle Valve B

1-2 Shift Valve

2-3 Shift Valve

3-4 Shift Valve
to select Line Pressure

Throttle B Pressure

Clutch Pressure

Servo Valve

Throttle Valve
Line PressureProCarManuals.com

As the engine turns, the oil pump also starts to operate. Automatic transmission fluid (ATF) is drawn from (99) and

discharged into (1). Then, ATF pressure is controled by the regulator valve and becomes line pressure (1). The torque

converter inlet pressure (92) enters (94) of torque converter through the orifice and discharges into (90).

The torque converter check valve prevents the torque converter pressure from rising.

Under this condition, the hydraulic pressure is not applied to the clutches.

(cont'd)
positionProCarManuals.com

Description

Hydraulic Flow (cont'd)

The line pressure (1) becomes the line pressure (4), (18), (25) as it passes through the manual valve. Also, the line pressure (1) goes to the modulator valve through the filter and becomes the modulator pressure (6). The modulator pressure (6)
is supplied to the 1-2 shift valve and 2-3 shift valve. The 1 -2 shift and 2-3 shift valves are moved to the left side because the shift control solenoid valve A is turned ON and B

is OFF by the
TCM.
The line pressure (18) is supplied to the 3-4 shift valve, and it is moved to the left side. The line pressure (4) is the 1st
clutch pressure (10), then the 1st clutch is engaged.
The line pressure (4) becomes the 1st-hold clutch pressure (16) via the 1-2 shift valve, 2-3 shift valve, 3-4 shift valve
and manual valve, then the 1st-hold clutch is engaged.

NOTE:
When used,
"left"
or
"right" indicates
direction
on the
flowchart.
PositionProCarManuals.com

The line pressure (1) becomes the line pressure (4), (25) as it passes through the manual valve.

The line pressure (1) goes to the modulator valve and becomes the modulator pressure (6). The modulator pressure (6)

is supplied to the 1-2 shift valve and 3-4 shift valve. The 1-2 shift and 3-4 shift valves are moved to the left side and

the 2-3 shift valve is moved to the right side because the shift control solenoid valve A and B are turned OFF by the

TCM.

The line pressure (4) goes through the 2nd clutch pressure (20) to the 2nd clutch, then the 2nd clutch is engaged.

The line pressure (4) passing through the orifice becomes the 1st clutch pressure (10) and flows to the 1st clutch.

However no power is transmitted by means of the one-way clutch.

NOTE: When used,
"left"
or
"right"
indicates direction
on the
flowchart.

(cont'd)
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