STI 6-Speed Transmission Swap FAQ's

Ever since we made our first two videos about swapping an STI 6-Speed into either the GD WRX (2002 - 2007) or the GR WRX (2008 - 2014), there are a number of common question that we have received. This is something that we have wanted to circle back to for a while now, and since we were helping Tasso Koch from OTC Racing put an STI 6-Speed transmission into his Rally car, we decided that this would be the perfect time to revisit some of these topics.

Hopefully this video with the others that we have put up will be able to answer any questions you might have, and we also go over some new solutions that are available when it comes to the wiring that is involved, etc.

The main topics covered in this video are:

00:00 - STI 6-Speed Swap FAQ Intro

00:42 - What are the wiring options to connect the STI 6-Speed to my WRX?

01:38 - Can I install a newer STI 6-Speed without a speed sensor into an older WRX?

02:15 - Neutral Position and Reverse Switch wiring between 5-speed and 6-speed

03:55 - Clutch compatibility between the 5-Speed and 6-Speed Transmissions

05:11 - Which driveshaft do you need for the swap, and which Rear Differential Flange?

06:20 - What rear differential do I need to go with the STI 6-Speed?

09:00 - What is involved to run STI Hubs on a WRX? And how are axles related?

12:35 - How can I swap an STI transmission into a narrow-body WRX? ( that is a 2008 - 2010 WRX)

Thanks for watching!

To follow OTC Racing, please check out:

Facebook: @obeythechihuahua
Instagram: @OTCracing

If you are interested, here are links to the parts that we discuss in the video:

iWire Adapter for 6-Speed conversion:

MAP Wheel Speed Sensor Signal Processors:

Differential Flanges:

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[iwiresubaruwiringsolutions]

You guys rock, such great distillation of a lot of 6 speed info!

[javiersurf]

You guys simply rock. Dispelling all the swap myths in one place....so great!!!

[Toua-Moua]

Great This is thousands upon thousands and years upon years of threads on the internet into one video. You guys are great!

[derrickquintal]

Always a plethora of information! Thank you for taking the time to make these videos!!

[thevincentpaul]

Great video! Time to start saving and buying parts and watching and rewatching and watching this video again.

[andresfritoorozco]

All the little bits of information are really helpful. I’m in the process of putting an 04STI trans in my auto 05 wrx.

[Gitzik]

Great video as always,
one note the gravel rotors came OEM on STI V6 RA(and 22B) it had 2 pots and an R180 Rear end, and can be purchased from Japan

[SpottedCow]

Thank you..this video made me realize the 08-10 narrow body rear hub is really different..was all looking the same. I shoulda know it was going to easy ;) Thanks again for the info!

[JonHowes]

Yep...your videos are awesome. Always super helpful.

[OggaDugga]

For those that are looking for simpler. Look into the TY856B1CA trans from the Version 7 STi RA. It’s the only 6 speed Subaru made that was non DCCD but has the front and matching rear lsd.

[AngelR]

i find it funny when someone says they want to do a budget build on a Subaru. do people even realize how expensive it is to make power on these cars?

[slofouru]

I have an 11 Sti 6mt in my 95, perfect fit with the og fwd braces removed from the tunnel.

[DGeorgeR]

You can also have the 2012 and later 6 speed trans machined to accept the speed transducer. It's a relative cheap and straight forward job, you just remove the front diff housing and take it to your machinist.

[kaerosfentis]

ive also noticed that the r180 rear diffs before the my06 sti that run the suretrak diffs have the smaller flange and the ones with the plated diffs run the larger flange. my06 and my07 stis had the larger flange.

[brianleggiero]

Excellent video! Can you possibly do a vid for the 08-09 LGT for swapping the STI 6-speed with DCCD?

[workingallday]

Great videos. We have a 2013 wrx. We were going to buy a 08-14 jdm 6 speed but ended up buying a wrecked 13 sti for the transmission/suspension. What are the differences between jdm and US trans? Thanks

[lucullustechnic]

Do you have any recommendation regarding the decision between the early DCCD with 35:65 torque split and the newer version with 41:59 torque split? As far as I know, the newer versions (2007+) have an additional mechanical LSD, but I'm not sure if this affects the vehicles handling in a positive or negative way. Subaru claims, that this mechanical unit makes the car more predictable to drive, but I always thought the big advantage of the DCCD would be that there's minimal load on the front tires when the controller completely unlocks the diff, resulting in optimal corner turn-in. Doesn't the mechanical LSD (even if it seems to have very low ramp angles) counteract this advantage? And what about the 6% difference in torque split, is this very noticible? I heard someone say that the 35/56 version is close to undriveable in open mode, but can it be worse than a rwd car? Sorry for this complex question, but i'm looking to do the swap in my legacy and i'm not sure which gearbox I should look for.

[Rynowhite]

So is the Neutral Safety switch the same on both the 07 STI and 02 WRX? I can't remember whether I used the WRX or STI, but now that I have everything back together, I'm having issues with my idle. I've already replaced the IACV with a new OEM one, adjusted the throttle cable and did a smoke test, but I'm still having issues. I'm suspect it might be the safety neutral switch. Thanks.

[Hunting_Party]

Having done the 08 sti swap into a narrowbody, the rear sti axle fits no problem.

[bryanthao]

I have a 14 wrx, assuming you're only talking about bolting up a 07 sti trans, my wrx front axles would work with sti trans(center diff), get 11-21 r180 rear sti axles, 08-14 r180 sti drive shaft, 07-14 r180 sti rear diff. w/ 3.545 gear ratio, 08-21 r180 sti rear diff mount crossmember, plug up speed sensor on trans, iwire plug n play harness for neutral and reverse switches. Wire in Map dccd controller. 06-21 sti clutcjlh slave cylinder, 04-21 sti clutch and flywheel. And any other essentials can be found in basic swap kit at flatironstuning. Let me know if im missing anything. Do I also need a sti starter or can I use the wrx starter ?