Category Archives: AWD

2004 – 2007 USDM STi breakdown

2004 – 2007 USDM STi breakdown:

A Stock 2005 USDM STi
A Stock 2005 USDM STi

Rev. D (2004)

In 2004, Subaru of America announced it would sell the WRX STi. Subaru Tecnica International’s president said in an interview with Road & Track magazine that he wished to beat the Mitsubishi Lancer Evolution in the US. Thus, each iteration of the US-spec WRX STi is essentially the same as the respective J-spec STi Spec C. All part numbers matched up, including the part-numbers for the glass windows and dampeners.

However, instead of the EJ207, the USA receives the first EJ257, a 2.5 liter version of the EJ207. Unlike the EJ207, it features hypereutectic cast pistons as opposed to the forged pistons in the EJ207. The steering rack is the standard STi’s 15.2:1 instead of the Spec C’s 13:1

2004 – 2007 USDM STi breakdown:

Rev. E (2005)
As with the Japanese-spec C models, US-spec STis received additional rear fender flaring in order to allow an increase in wheel size. The wheel size went from 17″ x 7.5″ to 17″ x 8″. In accordance with the increased wheel width, steering lock-to-lock turns have been reduced. Wheel hub strength was improved. The P.C.D. was changed from 5 x 100 to 5 x 114.3. The Suretrac front LSD in the 04 model was replaced with a helical unit, the rear differential remains the same clutch type unit. Torque split is set at 35/65. In the interior, the Stereo became standard. The badging has been revised and different look was given to the steering wheel, shift knob, HVAC controls, and center console.

2004 – 2007 USDM STi breakdown:

Rev. F (2006)
The US-spec STIs receive the same face lift as the Japanese-spec STIs. Mechanically speaking, the DCCD (Driver Controlled Center Differential) and the engine mounts have been changed. Like the Japanese-spec STIs engine mounts were changed from metal to liquid-filled plastic mounts to reduce vibrations into the car’s cabin. On the largest Impreza forum, North American Subaru Impreza Owners Club (NASIOC), 2006 owners have had issues with these plastic engine mounts.

The manufacturer will replace them, under warranty, if broken, with the 2005 rubber and metal mounts. Later 2006 vehicles were equipped from the factory with 2005 mounts. The center differential is updated with the addition of a mechanical limited slip mechanism to supplement the electromagnetic DCCD. The torque split is changed to 41/59. The 2006 STI weighs approximately 3,350 lb (1,520 kg).


Impreza WRX STi
Third generation STi

Third generation (2008-present)
Third generation (GR)
Production 2008-present
Body style(s) 5-door hatchback
4-door sedan(2011-)
Engine(s) 2.0L 304 hp (227 kW) H4
2.5L 305 hp (227 kW) H4
Transmission(s) 6-speed manual
5-speed automatic (w/SPORTSHIFT manual mode) (Japan, Hong Kong, Singapore, Indonesia, and Australia only)
Wheelbase 103.3 in (2,624 mm)
Length 173.8 in (4,415 mm)
Width 70.7 in (1,796 mm)
Height 58.1 in (1,476 mm)
Curb weight 3,373 lb (1,530 kg)
Related Subaru Forester
Subaru Impreza
Subaru Impreza WRX

Subaru Impreza WRX STI 2008The 2008 STI has received a higher degree of parts to differentiate it from its Impreza WRX brethren. Unlike the Impreza WRX, the STI uses aluminum suspension components, is only available as a 5-door hatchback, and has different fenders that are 2.2 in (56 mm) wider. It adopted “Subaru Intelligent Chassis Design” and “Dynamic Chassis Control Concept”. The turbo forces air through a larger top-mount-intercooler which has lost the red “STI” that was on previous generations. It is the first generation of this model with an automatic transmission which is able to import to outside Japan.

Like other 2008 Impreza models, the 2008 STI benefits from a lower polar moment of inertia due to smaller overhangs, and also features a double wishbone rear suspension.[16] The car also borrows new intake and exhaust components from the Legacy GT platform.

The latest Impreza WRX STI features Multi-mode Vehicle Dynamics Control (VDC) with “Normal”, “Traction”, and “Off” modes, Subaru Intelligent-Drive (SI-Drive) with 3 modes: Intelligent, Sport, and Sport Sharp (S#), and Multi-mode Driver’s Controlled Centre Differential (DCCD). The DCCD enables driver to select the manual or auto: “auto”, “auto+”, and “auto-” mode in order to distribute the torque based on driving preference or conditions.

Subaru Impreza WRX STI (Japan)The JDM version has a 2.0L 308 PS (227 kW; 304 bhp) EJ207 engine with a Twin scroll turbocharger, while other versions of the car have a 2.5L 300 PS (221 kW; 296 bhp) EJ257 engine with a single-scroll VF48 turbocharger.

The second generation Subaru Impreza WRX STi

Subaru Impreza WRX STi winter driving.
Subaru Impreza WRX STi winter driving.

Second generation (2001 – 2007)
Second generation (GDB-F)
Production 2001-2007
Body style(s) 4-door sedan
4-door station wagon
Engine(s) 2.0L H4
2.5L H4
Transmission(s) 6-speed manual
5-speed semi-automatic
Wheelbase 2004-05: 100.0 in (2540 mm)
2006-08: 99.4 in (2525 mm)
Length 2004-05: 173.8 in (4415 mm)
2006-08: 175.8 in (4465 mm)
Width 68.5 in (1740 mm)
Height 56.3 in (1430 mm)
Curb weight 3,296 lb (1,495 kg)
Related Subaru Impreza
Subaru Forester
Subaru Impreza WRX
Saab 9-2X
In 2001, the Impreza line received a complete update. The chassis was stiffened so that it had 120% torsional stiffness increase. The WRX STi gained 17″ x 7.5″ alloy wheels over the previous 16″ x 7″ wheels. The 5 speed manual transmission (reputed to be one of the car’s weakpoints) was changed to an STi engineered 6 speed manual transmission. The engine was retained from the Version 6 STi and still retains the semi-closed deck block and is still labeled as the EJ207, However, the turbochargers are IHI models. The interior was updated with a STi logo on the gauge. The STi’s tachometer also has a red shift light. The STi’s and optioned Type RA STi have received Brembo 4 piston front and 2 piston rear brakes while the bare-bones Type RA STi still carried the Subaru 4 piston front and 2 piston rear brakes. Externally, the STis had larger hood scoops and had foglight covers with STi embossed on them. The DCCD was updated so it can work with anti-lock brakes. During braking, when the ABS is on, the DCCD will set itself to open-mode (no locking).

The version nomenclature was dropped from the name. Japanese and other auto-enthusiasts often refer to the chassis as GDB/GDF (the STi has a ‘B’ or ‘F'(for USDM models) where as the regular WRX had an ‘A’). The fourth character of the VIN gives the revision (A to F where G is the 2007 version).

For quick and easy reference to the different exteriors, Subaru Impreza owners use nicknames based on the headlights. Each relates to a creature that has similar looking eyes: 2002-2003 are ‘bug eyes’ / 2004-2005 are ‘Tear Drop’ or ‘blob eyes’ / 2006-2007 are ‘hawk eyes’.

GC8 the first generation Subaru Impreza WRX STi

GC8 the first generation Subaru Impreza WRX STi:

Photo Credit: Barry DufekPhoto Credit: Barry Dufek
Photo Credit: Barry Dufek /

One common misconception is that every Impreza between 92-01 were “GC8’s“. The code breakdown is as follows; G – stands for Impreza, C – sedan, M – coupe, F – station wagon, The 8 stands for the 2.0 L turbo motor.

First generation (GC8)
Production 1992-2001
Body style(s) 2-door coupé
4-door sedan
5-door station wagon
Engine(s) 2.0 L H4
Wheelbase 99.2 in (2520 mm)

There were six versions of the GC8 STi. The different versions were marketed with consecutive numbers. Another way to tell the version of a WRX STi was to look at the chassis code. Sedan STi Model Codes were GC8, Coupes were GM8 and Station Wagons were GF8, followed by a letter from A to G. There was a GC chassis version of the RS released in 2001 as well in the United States.

One common misconception is that every Impreza between 92-01 were “GC8’s“. The code breakdown is as follows; G – stands for Impreza, C – sedan, M – coupe, F – station wagon, The 8 stands for the 2.0 L turbo motor. So really, there are many combinations. A coupe STi would be GM8, sedan GC8, wagon GF8. Also, the code for the coupe American 2.5RS’s were GM6 (6 standing for the 2.5 L N/A motor)

A JDM Sti Coupe has the code GC8. For example, a version 4 STi coupe has the code GC8 2DD, with the 2 representing 2-doors.

Version I (10/92 – 08/94) – GC8 A/B
The first STi was known simply as WRX STi (there was no “version” moniker added to the name until the version II). 100 Imprezas per month were produced starting from February 1994. In March, production was stabilized to 100 STis a month. It had 250 PS (184 kW; 247 bhp) at 6500 rpm and 31.5 kgf·m (309 N·m, 228 ft·lbs) at 3500 rpm and weighed 1230 kg (2,710 lb). Before the STi, the highest trim line of the Impreza was the WRX and the WRX RA, first manufactured in November 1992. This version of the STi was the only version where the standard cars were taken at the end of the assembly line and replaced by STi parts. After this version, the standard STi was built alongside the WRX on the production lines.

The WRX STi Type RA (marketing has made usage of the RA acronym in various ways; Record Attempt[6] is the current usage. “R = Racing, A = Group A, FIA the racing class the WRC Impreza competes in” has also been confirmed by Subaru of Japan; the correspondence can be seen on the discussion board for this article) produced 275 PS (202 kW; 271 bhp) and 32.5 kgf·m (319 N·m, 235 ft·lbs) of torque. This version of the WRX STi was a stripped out car that had no sound-deadening, radio or air-conditioning. It came sparsely equipped as it was to be sold to racing teams that would throw out the racing parts. This version of the WRX came with a Driver Controlled Center Differential (DCCD). This device was an electromechanical differential that could lock the differential. The DCCD would be beneficial to people who used it in various rally conditions.

5spd Subaru WRX five speed manual tips and tricks

5spd Subaru WRX five speed manual tips and tricks:

So you’ve got this noise coming from your 5spd transmission. It is starting to whine when you’re on/off the throttle. The sound seems to come right from below like around the shifter area. You may be a victim of the infamous falling apart center differential!

Don’t be too worried, transmissions are a dime a dozen! You still have the option to go 6spd or another 5spd transmission with different gear ratios if you choose.

 5spd: The damage. Most times the rear cover will back out minor like this photo. Other times it will completely come off. You can see the circlip survived this incident.
5Spd: The damage. Most times the rear cover will back out minor like this photo. Other times it will completely come off. You can see the circlip survived this incident on this WRX

How to not tow a Subaru like a idiot

If there is one thing you never do with a manual all wheel drive Subaru is tow it with car dollies without removing  the drive shaft. Really the preferred way of towing a Subaru is putting the Subaru on a flatbed or a car trailer.


Kind of a bad idea.
Kind of a bad idea.


Having the Subaru towed on the two rear wheels is asking for the all wheel drive system to die a horrible death and to leave a trail of parts and tears on the road. It’s a great way to need to install if you are lucky a new center differential or if you are unlucky your transmission will need a complete replacement.


Let me blind you with my Subaru Forester

Nothing quite like getting the attention of every cop in your city with your blue tinted headlights with your Subaru Forester.  If a cop doesn’t pull this clown over he is going to blind and piss off every motorist this clown drives by. Someone needs to tell this guy its illegal to have blue and red lights on your vehicle.  I’m sure that this Forester is a rally champion and needs all the light it can get for those dangerous night time rally stages at the Rally America events.




Oh are is that a LED light bar in his hood scoop? Talk about obnoxious.

How to wreck your AWD on a Subaru 101

The easiest way to destroy your differentials in your Subaru is to drive around on different sized tires. Most people recommend around 2/32 maximum tread difference between all four tires. A great way to have to replace all 3 differentials is to just 100+ miles on a tire that isn’t the same height as the rest of your tires.




This is why you carry a full spare or if you have to have a AAA membership.  I would be weary of driving 30 miles on a spare that I know is the correct size for the rest of the drives never mind 100+ miles.