Subaru AWD Transmissions

Subaru has fitted 2 main transmission types into the Impreza and Liberty/Legacy AWD models, both a 5 speed (TY75) and 6 speed (TY85) models.

5MT (TY75)

Fitted to vehicles since 1989 onwards, the TY75 is a 5 speed transmission incorporating both the vehicles front and center differentials within the single unit. Front differentials are a combination of open and helical LSD and center differentials fitted with either a viscous coupling or DCCD (Driver Controlled Center Differential) consisting of a computer controlled electromagnetic clutch pack.

Throughout the years, Subaru have made a number of running changes and revisions to improve the durability and shift feel of the TY75. These changes include the widening of 1st, 2nd and 3rd gears, the introduction of dual cone sychronizers to various gears and the change of synchronizer teeth length and engagement angles to minimise gear pop-out and shift baulking.

The TY75 is often referred to as the "Glass Transmission" in Japan and other parts of the world due do it's low torque capacity and it's tendancy to break gears in lightly and even standard unmodfied vehicles.

A particularly troublesome point in the 5MT TY75 shift mechanism is the 3rd gear synchroniser cone. The shock load exerted from hard shifting, especially if the clutch has not been fully engaged often breaks the legs off or breaks the cone. This can affect shift quality and in extreme cases damage the gears in the transmission if metal fragments are ingested into meshing gears.

6MT (TY85)

Predomininantly fitted to STI vehicles, the TY-85 was developed to help extract maximum power from the WRX STi’s powerful, albeit more peaky engines. This transmission is similar in layout to the 5MT TY75 with the front and center differentials incorporated within the single unit.

The TY85 is lubricated internally by an oil pump mounted at the rear of the unit which gear driven by the center differential. The lubricant flow rate is governed by both the center differential's speed and built in regulator/pressure relief valve system.

Even though the TY85 transmission's superior torque capacity and extra features are much sought after by owners of 5MT vehicles, the close ratios fitted to earlier models tends to make it unsuitable for modified vehicles with built up engines that have wide power and torque curves. The cost of retrofitting acilliaries is also prohibitive for many vehicle owners.

Subaru 5MT Transmission Solutions

PAR designs and manufactures both synchromesh and dog engagement gearsets for the Subaru AWD 5 speed transmission. There are currently 4 gearset models manufactured to fit the TY75(5MT) including 2 synchromesh engagement (option of helical and straight cut) and 2 dog engagement options and a wide ratio gearset for the TY85(6MT) transmissions. Details of each option follow below.