TY856W(XXXX): An Overview of the Changes Over the Years (2004-Present)

[Alin]

STi Transmissions

TY856W(XXXX): An Overview of the Changes Over the Years
2004-Present
(USDM models)

2004 (2003 Production models):

Transmission Code: TY856WH3MA


Early 2004 WRX STi models came with axle stubs inserted in the transmission with female front axles.

​

Axle Differentials:
-Center: DCCD (Driver Controlled Center Differential) front/rear power split, 6 levels or auto mode, with indicator light
-Front: "SureTrac" Limited-slip front axle
-Rear: Mechanical Limited-slip rear axle

Transmission:
-6 speed manual with transmission cooler

Gear Ratios:
-1st: 3.636
-2nd: 2.375
-3rd: 1.761
-4th: 1.346
-5th: 0.971
-6th: 0.756
-Reverse: 3.545
-Transfer Reductions: 1.000
-Final Drive: 3.900
-Center Differential Type: DCCD (35/65)
-Front Differential Type: A. P. Suretrac
-Rear Differential Type: R180 - Plated

2004 (2004 Production models):

Transmission Code: TY856WH4MA

Late 2004 WRX STi models came without the stubs and instead had male front axles.

​

Axle Differentials:
-Center: DCCD (Driver Controlled Center Differential) front/rear power split, 6 levels or auto mode, with indicator light
-Front: "SureTrac" Limited-slip front axle
-Rear: Mechanical Limited-slip rear axle

Transmission:
-6 speed manual with transmission cooler

Gear Ratios:
-1st: 3.636
-2nd: 2.375
-3rd: 1.761
-4th: 1.346
-5th: 0.971
-6th: 0.756
-Reverse: 3.545
-Transfer Reductions: 1.000
-Final Drive: 3.900
-Center Differential Type: DCCD (35/65)
-Front Differential Type: A. P. Suretrac
-Rear Differential Type: R180 - Plated

2005:

Transmission Code: TY856WW6MA

​

Axle Differentials:
-Center: DCCD (Driver Controlled Center Differential) front/rear power split, 6 levels or auto mode, with indicator light
-Front: "Helical" Limited-slip front axle
-Rear: Mechanical Limited-slip rear axle

Transmission:
-6 speed manual with transmission cooler

Gear Ratios:
-1st: 3.636
-2nd: 2.375
-3rd: 1.761
-4th: 1.346
-5th: 0.971
-6th: 0.756
-Reverse: 3.545
-Transfer Reductions: 1.000
-Final Drive: 3.900
-Center Differential Type: DCCD (35/65)
-Front Differential Type: Helical LSD
-Rear Differential Type: R180 - Plated

2006:

Transmission Code: TY856WW7MA

This is the first year that came with the 1.1:1 reduction gear.

​

Axle Differentials:
-Center: DCCD (Driver Controlled Center Differential) front/rear power split, 6 levels or auto mode, with indicator light. Up to 41% front/ 59% rear power split. New steering wheel sensor
-Front: "Helical" Limited-slip front axle
-Rear: Mechanical Limited-slip rear axle

Transmission:
-6 speed manual with transmission cooler

Gear Ratios:
-1st: 3.636
-2nd: 2.375
-3rd: 1.761
-4th: 1.346
-5th: 0.971
-6th: 0.756
-Reverse: 3.545
-Transfer Reductions: 1.100
-Final Drive: 3.900
-Rear Final Drive: 3.545
-Center Differential Type: DCCD (41/59)
-Front Differential Type: Helical LSD
-Rear Differential Type: R180 - Plated

2007 (Early 2007 Production models):

Transmission Code: TY856WW8MA


​

Axle Differentials:
-Center: DCCD (Driver Controlled Center Differential) front/rear power split, 6 levels or auto mode, with indicator light. Up to 41% front/ 59% rear power split. New steering wheel sensor
-Front: "Helical" Limited-slip front axle
-Rear: Mechanical Limited-slip rear axle

Transmission:
-6 speed manual with transmission cooler

Gear Ratios:
-1st: 3.636
-2nd: 2.235
-3rd: 1.521
-4th: 1.137
-5th: 0.971
-6th: 0.756
-Reverse: 3.545
-Transfer Reductions: 1.100
-Final Drive: 3.900
-Rear Final Drive: 3.545
-Center Differential Type: DCCD (41/59)
-Front Differential Type: Helical LSD
-Rear Differential Type: R180 - Torsen

2007 (Late 2007 Production models):

Transmission Code: TY856WW8MD


​

Axle Differentials:
-Center: DCCD (Driver Controlled Center Differential) front/rear power split, 6 levels or auto mode, with indicator light. Up to 41% front/ 59% rear power split. New steering wheel sensor
-Front: "Helical" Limited-slip front axle
-Rear: Mechanical Limited-slip rear axle

Transmission:
-6 speed manual with transmission cooler

Gear Ratios:
-1st: 3.636
-2nd: 2.235
-3rd: 1.521
-4th: 1.137
-5th: 0.971
-6th: 0.756
-Reverse: 3.545
-Transfer Reductions: 1.100
-Final Drive: 3.900
-Rear Final Drive: 3.545
-Center Differential Type: DCCD (41/59)
-Front Differential Type: Helical LSD
-Rear Differential Type: R180 - Torsen

2008-2014:

Transmission Code: TY856UW1MA


​

Axle Differentials:
-Center: DCCD (Driver Controlled Center Differential) front/rear power split, 6 levels or auto mode, with indicator light. Up to 41% front/ 59% rear power split. New steering wheel sensor
-Front: "Helical" Limited-slip front axle
-Rear: Mechanical Limited-slip rear axle
-VDC (vehicle dynamics control) electronic stability control with normal, traction and off modes (use VDC button), Includes multi-mode DCCD Driver Controlled Center Differential with nine settings, including three auto modes and six manual ones.
-The 3 DCCD modes are 'Auto' for center differential lock-up controlled by the Transmission Control Module, The 3 auto modes are Auto, Auto Minus shifts torque to the rear for high-friction surfaces, and Auto Plus shifts torque to the front for low-friction surfaces.
-DCCD manual modes vary rear/front power up to 50/50 split.
The 6 settings are rear/front: 59/41, 57.2/42.8, 55.4/44.6, 53.6/46.4, 51.8/48.2, 50/50.
-

Transmission:
-6 speed manual with transmission cooler

Gear Ratios:
-1st: 3.636
-2nd: 2.235
-3rd: 1.521
-4th: 1.137
-5th: 0.971
-6th: 0.756
-Reverse: 3.545
-Transfer Reductions: 1.100
-Final Drive: 3.900
-Rear Final Drive: 3.545
-Center Differential Type: DCCD (41/59)
-Front Differential Type: Helical LSD
-Rear Differential Type: R180 - Torsen

2015-2018?:
​

Transmission Code: TY856UW9AA​

This is going to be a future sticky thread. This is going to be a massive and ambitious overview on the changes done of the STi transmission over the years. This will take a lot of time and thorough research until it gets completed and will constantly be edited with new information. This will be based off of the USDM transmissions from 2004 to present time.




Sources:
http://www.cars101.com/subaru/impreza/wrxsti2004.html
https://en.wikipedia.org/wiki/List_of_Subaru_transmissions#Impreza_WRX_STi_and_Legacy_spec._B
https://www.flatironstuning.com/subaru-oem-sti-transmissions-6-speed
https://forums.nasioc.com/forums/showthread.php?t=1443215
https://forums.nasioc.com/forums/showthread.php?t=181343
https://www.rallispec.com/downloads/Transmission ID Chart_Public.pdf
https://www.xcceleration.com/gear_ratios.html
http://autojunkee.com/subaru-gear-ratio-reference-guide/
http://www.gearhack.com/myink/ViewPage.php?file=docs/Subaru Transmission Chart
https://highgeartransmission.com/subaru-transmissions/
https://forums.nasioc.com/forums/showthread.php?t=2899678
https://legacygt.com/forums/showthread.php/transmission-gear-ratios-and-final-drives-229267.html​

 

[Alin]

@IGOTASTi @HolyCrapItsFast @Batmobile_Engage @Grinder34 @black bandit@Boogieman98 @Eagleye@Raven32 @War_Panda04

Hard to find information on 2015+ at the moment.

If you have any propositions, hypotheses, guidance, advocacy, ideas, exhortations, comments, theories, suggestions, opinions, philosophies, and/or recommendations as to what needs to be added, changed, or removed, please let me know. :tup: