2000-Subaru Impreza STi Manual Transmission Material

2000 Subaru Impreza STi Model: GDB Engine Model: EJ207 Transmission Model: TY 85

Overview of 6-speed manual transmission and operation system

In order to control the torque of STi specification DOHC high power turbo engine (maximum output 206kW-maximum torque 373Nm) to plan a running woman negative factory, a full-time 4WD 6-speed manual transmission is adopted and the operation system is improved together . In order to respond to the high power of the engine as an operation system, we are aiming to improve the startability by increasing the clutch capacity and improving the clutch oil pressure gauge.

Main features of full-time 4WD 6-speed manual transmission
  • The double cone synchromesh mechanism is adopted for 1st gear, 3rd gear, reverse, and the triple cone synchromesh mechanism is adopted for 2nd gear to improve durability and operability.
  • The main case is of the same split type to improve rigidity.
  • The reverse gear is always meshed.
  • An oil pump is placed on the main case.
  • The front differential is equipped with a torque sensitive cam type LSD, and the center differential is equipped with a driver’s control type or viscous coupling type.
  • The gear shift system employs a floor shift parallel link type, slider type reverse operation error prevention mechanism.

Clutch and operation system

The clutch disc is increased in clutch capacity from the conventional outer diameter x inner diameter: 230 mm x 150 mm to 240 mm x 160 mm. The clutch operating system is a hydraulic pull type, and an orifice is provided in the hydraulic circuit to prevent sudden clutch engagement.

Hydraulic control system

The clutch master cylinder is a conventional type, and a clutch orifice is added to the hydraulic circuit between the clutch master cylinder and the clutch operating cylinder to reduce the shock torque at the time of clutch connection, and also inside the orifice A compression spring made of shape memory alloy is provided on the to secure the hydraulic circuit so that the clutch operation delay due to the orifice does not occur at low temperature.

  • Normal temperature operation

The clutch orifice is integrally disposed in the clutch operating cylinder, and comprises an orifice retainer, an orifice valve and a compression spring. The orifice valve is normally pressed against the body by a compression spring No1.

  • Low temperature operation

When the temperature is low, the compression spring No. 1 made of shape memory alloy contracts and no spring action occurs, and the compression spring No. 2 presses the orifice retainer against the orifice retainer to secure a sufficiently wide oil passage.

About 6-speed transmission

Specification chart

Transmission mechanism

The transmission mechanism has two main transmission gears in parallel with the main shaft and drive pinion shaft, and is always engaged with six forward gears and one reverse gear, and reverse reverses the direction of rotation via the reverse idle gear. It is a method to make

All gears adopt helical gears, review gear specifications and tooth width, and increase the gap between the main shift gears to 85 mm to improve gear strength.

  • Synchromesh mechanism

The synchromesh mechanism adopts multi-cone synchro for the first to third gears and the reverse to reduce the shift operation force. The reverse synch is disposed in the reverse idle gear section.

In addition, asymmetric gear dog gear is adopted for 2nd to 6th gears to improve operability.


Synchromesh mechanism

  • Reverse gear

As the reverse gear is always meshed, a reverse idler gear No. 1 is equipped with a scissors gear to improve quietness.

The reverse idle gear is composed of a reverse idle gear N01, a scissors gear, a spring friction plate and a snap ring.

By sandwiching the drive-side gear with a spring-loaded scissors gear and an idler gear, the gear backlash is set to 0 to prevent rattling due to engagement of the gears.

Reverse gear

Shift and select mechanism

The shift pattern is a floor shift system with six forward and one reverse stages, with slide ball bearings in each rod support and friction built-in plungers in the shift and detent mechanism. Has been realized, and its operability has been improved.

The select mechanism unit realizes a short select stroke as a parallel link system. The interlock (double engagement prevention) mechanism adopts a slider pull-up type as a reverse check (reverse malfunction prevention) mechanism as a block type.

  • Shift-dident mechanism and rod support structure

The shift and dent mechanism prevents the gear from being lost by the check ball. A small ball is embedded in the back of the check ball section.

Slide rod bearings are used for each rod support.

Shift-divert mechanism

  • Select return mechanism

The select and return mechanism is composed of a shifter arm shaft, selector arms (Nos. 1 and 2), a striking rod and a set spring (neutral).

Select return mechanism

The select return force corresponds to the movement of the selector arm, and the fulcrum on the selector arm spreads the set spring (neutral) and is generated by the return force of the spring.

Selector arm movement

  • Interlock mechanism

The interlock mechanism is a block type, and the reverse is arranged independently in the layout.

Reverse check mechanism

4WD transfer device (center differential)

The 4WD transfer device is compactly housed in the center differential LSD between the drive pinion shaft for driving the front wheels and the transfer gear for driving the rear wheels. There are two types of LSD: viscous coupling method and driver’s center differential. Here, driver’s center differential is explained.

Driver’s control center differential

The basic structure is a planetary gear system in the center differential, the operation limiting device is an electromagnetic crimp variable control multi-disc clutch, and the front-rear drive distribution is 45:55. In addition, the overall length has been shortened to reduce the outer diameter of the planetary gear and multi-disc clutch in order to cope with six speeds.

Driver’s control center differential

  1. When current flows in the electromagnetic coil, a magnetic field is generated between the electromagnet, the differential case, the pilot clutch, and the armature.
  2. The pilot clutch and armature are attracted to the electromagnet by the next induction action, and the rotational torque (pilot torque) of the differential case rotates the cam NO2.
  3. When the cam NO2 rotates, the rotation is different from that of the cam NO1, so that the ball generates a rolling thrust force and slides the axially movable planetary gear to press the main clutch to generate a differential limiting torque.
  4. Since the strength of the magnetic field increases in proportion to the amount of current flowing, the differential limiting torque also increases in proportion to the amount of current. Also, the amount of current can be changed in five steps by the driver operating the control switch.

Front differential

The front differential adopts a large-sized hypoid gear (R180) to support high output. In addition, a torque sensitive cam type LSD is set as a manufacturer option for the front differential.

Torque sensitive cam type LSD

The structure is the same as that of the torque sensitive cam type LSD adopted for the rear differential, and has a feature that the selection range of the torque bias ratio is large.

Since no relative rotation occurs between the left and right face and cam during straight running, input torque from the drive gear is transmitted from the side of the cam follower to the face cam.

When relative rotation occurs on the face and the top notch due to turning or slip, the cam follower transmits torque to the face cam while reciprocating to the left and right.

Torque sensitive cam type LSD

Transmission and lubrication system

An oil pump is provided at the rear of the main case, and is pumped to lubricating passages such as the main shaft, drive pinion shaft, and transfer to forcibly lubricate each part, and an oil chamber is provided to reduce agitation resistance, I am trying to improve the efficiency.

The oil pump is a thin trochoid type, driven by a gear that is integrated with the center differential case, and a regulator valve and a relief valve are arranged on the discharge side.

Lubrication system


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