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2000 Impreza 2.5RS BRP
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I figured I'd start this thread to catalog the different six speed swaps and configurations available to the GC8. I'll list a few common configurations and parts lists.

To answer the usual newbie question: Any EJ motor (any Impreza motor) will bolt up to any EJ transmission, and the six speed is no exception.

1. Full STi driveline swap
STi 6 speed clutch
STi 6 speed flywheel
STi 6 speed pressure plate
STi 6 speed clutch slave cylinder
STi 6 speed transmission
STi 6 speed transmission mount
STi 6 speed shift linkage
STi 6 speed drive shaft
STi front axles
STi front hubs
STi R180 rear differential (final drive matching that of the transmission)
STi R180 rear axles
STi R180 rear hubs
STi front and rear Brembos
STi Brembo rotors front and rear
(If using '05-'07 hubs, custom coil overs are recommended to maintain proper suspension geometry to mate from the 5x114.3 bolt pattern to the GC top hat bolt patterns. These custom coil overs would be GC top hats with a '05-'07 STI bottom sleeve to mount to the hub)

2. Version 6 style driveline swap (maintains 5x100 bolt pattern, allows for use of 16" wheels over 4/2 pot brakes while keeping R180)
STi 6 speed clutch
STi 6 speed flywheel
STi 6 speed pressure plate
STi 6 speed clutch slave cylinder
STi 6 speed transmission*
STi 6 speed transmission mount
STi 6 speed shift linkage
STi 6 speed drive shaft
Stock GC front axles
Stock GC front hubs
STi R180 rear differential (final drive matching that of the transmission)
STi R180 rear axles
2004 STi R180 rear hubs
STi / WRX 4/2 pot brake calipers
WRX 4 pot front brake rotors
DBA Group N rear gravel rotors or later model JDM GC8 R180 2 pot brake rotors


3. STi/WRX hybrid driveline swap (cheaper than the previous two setups, many WRX drivers choose this because they already have the matching rear end)
STi 6 speed clutch
STi 6 speed flywheel
STi 6 speed pressure plate
STi 6 speed clutch slave cylinder
STi 6 speed transmission*
STi 6 speed transmission mount
STi 6 speed shift linkage
Impreza 4EAT automatic transmission drive shaft
Stock GC8 front axles
Stock GC8 front hubs
WRX R160 rear differential (final drive matching that of the transmission)
Stock GC R160 rear axles
Stock GC R160 rear hubs
Stock GC brake calipers
Stock GC front and rear brake rotors


4. STi/WRX hybrid axle swap (cheaper than the previous three setups, you get the stronger R180, but the weak link is the axles)
STi 6 speed clutch
STi 6 speed flywheel
STi 6 speed pressure plate
STi 6 speed clutch slave cylinder
STi 6 speed transmission*
STi 6 speed transmission mount
STi 6 speed shift linkage
STi 6 speed drive shaft
Stock GC front axles
Stock GC front hubs
STi R180 rear differential (final drive matching that of the transmission)
STi R180 rear axles
Stock GC R160 rear axles - Use the four rear axles and a custom race by suberdave of NASIOC to make a hybrid axle to use your stock hubs
Stock GC R160 rear hubs
Stock GC brake calipers
Stock GC front and rear brake rotors

*Note: Depending on the transmission you are swapping in, you may need to purchase axle stubs, seals, and circlips to mate your female axles to your female transmission. This essentially converts your '05-'07 female transmission to a male transmission that will mate to GC female front axles. Additionally, it is possible to obtain an '04 STi transmission that has had these parts removed. The following part numbers are here:
Early 2004 Axle Seal Part Numbers (to be used with axle stubs / female axles):
Left: 806730041
Right: 806730042
Circlips (You need two of these): 805329010
Axle Stubs (You need two of these): 38415AA110

Clutch/Flywheel/Pressure Plate/Slave cylinder notes:
It is possible to use an '02-05 WRX pull style slave cylinder, clutch, flywheel, and pressure plate with a six speed swap, but since the RS is a push style system, you would have to source these parts anyway, as none of it could be reused.

Final Drives:
'02-'05 USDM WRX 5MT: 3.54
'04-'05 USDM STI 6MT: 3.90
'06-'07 USDM STI 6MT: 3.54
Based on these final drives, it is possible to use an '02-'05 WRX 3.54 final drive R160 rear differential with an '06-'07 STI 3.54 final drive 6MT transmission. Other combinations of trans and rear diff will require the ring and pinion on the rear differential to be swapped to the proper final drive.

Six speed transmission codes and details (this helps immensely when picking a transmission based on features):
Master 6 Speed Transmission Decoder Ring - NASIOC

'08+ STI 6 speed transmissions:
08+ STI transmissions are slightly different to swap into an older model (GD's included) because they don't have vehicle speed sensors for the older ECU's and speedometers, and the newer ECU's and speedometers instead rely on the CANBUS system to relay a speed signal from the ABS sensors. To remedy this, you can use one of the two solutions:
VSSPro: A device built to read the ABS ring sensors and convert that to a speedo signal found here.

Earlier 6MT bell housing swap:
You need the following parts to swap to a pre-08 6MT bell housing that includes a VSS (thanks to seangfy).
32001AA210 GASKET & SEAL KIT-MANUAL TRANSMISSION FIG-111 3232001 1

30400AA040 HOUSING ASSEMBLY-CLUTCH FIG-112 3030400 1

32024AA011 GAUGE ASSEMBLY-OIL LEVEL FIG-112 3232024 1

806912140 O RING FIG-112 G9G9121 1

031512000 SNAP RING-OUTER FIG-117 1

32714AA360 GEAR-SPEEDOMETER DRIVEN FIG-117 3232714 1

32713AA050 SHAFT-SPEEDOMETER FIG-117 3232713 1

803012060 WASHER FIG-117 D0D0120 1

805012020 SNAP RING-OUTER FIG-117 F0F0120 1

806712100 OIL SEAL FIG-117 G7G7121 1

32715AA050 GEAR-SPEEDOMETER DRIVE FIG-190 3232715 1

38415AA110 SHAFT-AXLE DRIVE FIG-190 3838415 2

805329010 CIRCLIP-INNER FIG-190 F3F3290 2

806730042 OIL SEAL FIG-190 G7G7300 1

806730041 OIL SEAL FIG-190 G7G7300 1

I believe that's about it, I'll add information I as I deem it to be necessary.
 

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ALL THE STI PARTS
01 RSTI w/07 EJ257, Brembos
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1,813 Posts
Fuuuuu read it 3 times too and still missed it! Don't mind me then! :D

Can you also use the 4EAT GC driveshaft? I thought they were the same length?
 

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2.0L Turbo
1998 2.5RS Black EJ205
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3,870 Posts
And that's what I plan on running. It will probably end up being sooner rather then later. Haha

Nice write up!
 

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IwannadrivelikeBunta
'98 RSTi, '10 LGT, '17 FXT
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3,607 Posts
*Note: Depending on the transmission you are swapping in, you may need to purchase axle stubs, seals, and circlips to mate your female axles to your female transmission. This essentially converts your '05-'07 female transmission to a male transmission that will mate to GC female front axles. The following part numbers are here:
Early 2004 Axle Seal Part Numbers (to be used with axle stubs / female axles):
Left: 806730041
Right: 806730042
Circlips (You need two of these): 805329010
Axle Stubs (You need two of these): 38415AA110
Since the axle stubs are removeable, it is possible to purchase an 04 STi transmission and have the axle stubs missing as was my case.
 

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1999 2.5RS RBP
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18 Posts
THANK YOU!!! Awesome source of good info. I've been reading stuff scattered around various threads for a few days now. PLEASE, make this sticky.


I don't suppose you could add the info for the "custom" coil-over setup for using 05-07 hubs?
 

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White '99 Impreza RSTi
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27 Posts
VERY Well put!!
I'm doing the 3rd Option - STi/WRX Hybrid driveline swap

So here's my dilemma; I have an 05 STi transmission (female) and since those axles (male) don't work in my stock RS hubs, I want to go with my stock RS axles (female). East Coast Swappers was one of the places that told me to purchase the axle stubs, seals, and circlips. Like I mentioned in my post, I just tried swapping the STi stubs to the RS stubs. no such luck.

I got the impression that these stubs would go on to the female axles themselves. But it seems like your write up here is implying to add them to the transmission side. Am I reading that correctly?
 

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2000 Impreza 2.5RS BRP
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3,543 Posts
Discussion Starter #13
Yes, the axle stubs, seals, and circlips actually go into the transmission to allow you to use the female axles. They replace the existing axle seals that are in the female transmission.
 

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Discussion Starter #15
The stubs only come standard with the '04 STI trans. For a different year, you'll have to order the provided part numbers from a Subaru dealer.
 

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White '99 Impreza RSTi
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Yes, the axle stubs, seals, and circlips actually go into the transmission to allow you to use the female axles. They replace the existing axle seals that are in the female transmission.
Gotcha! Ok I understand. I tried calling a couple subie dealerships this morning. Both had the seals, but would have to order the circlips and stubs. Stubs being around $50 each (woah).

This morning I also pulled apart my old front LSD and put the stubs on my female RS axles, but the circlip position/thickness is a lot different than the STi stub (yet another fail).

I found a local guy who is willing to sell me his '06 WRX Axles (male). Question to you is, would they fit my RS?

It looks like they would, but I'm a little nervous since nothing else I've done is working.



Here is a comparison I found of an '06 WRX Axle (top) and I'm assuming '06 STi axle (bottom). Can you verify if it'll work or if they are too big/too long for my RS hubs?

Thanks!!
 

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2000 Impreza 2.5RS BRP
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Discussion Starter #17
The 5MT axle stubs are different from the 6MT stubs.

As far as the axles go, the WRX axles will likely fit, but I can't say for certain. However,the sedan WRX axles are longer than the GC axles, and might wear faster due to the CV joints being constantly at harder angles. I would recommend going the route of the stubs.
 

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97 STi
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Clutch/Flywheel/Pressure Plate/Slave cylinder notes:
It is possible to use an '02-05 WRX pull style slave cylinder, clutch, flywheel, and pressure plate with a six speed swap, but since the RS is a push style system, you would have to source these parts anyway, as none of it could be reused.
So basically if you're switching from a jdm 5spd all you need is the trans/mount/linkage, 4eat shaft, matching diff ratio, and maybe stubs?

This would be too easy for me to pass on. Thanks for the awesome writeup, sticky for sure. Here are all the six speed codes;

Master 6 Speed Transmission Decoder Ring - NASIOC
 

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2000 Impreza 2.5RS BRP
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Discussion Starter #19
Provided your JDM 5 speed trans is a pull type clutch, you're correct. And thanks for the trans code link, I added that to the post :)
 
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