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Old 04-03-2021, 03:15 PM   #1
VeteranNoob
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OMGHi2U Is it possible to use 02-07 STI gears with a 2019 WRX [involving transmission swap]?

To clarify, I'm wondering if there's any transmission my 2019 WRX can use which will be compatible with a 02-07 STI transmission gearset; I know I'll need to swap transmissions- I'm just wondering if any of my options support that gearset.

First, let's get this out of the way: No, I do not want to trade in for an STI- in fact, reading on, you'll see that's not even actually a solution for me.

"Why? What are you doing?"...

Right now I'm considering swapping to the STI transmission and using a CAE shifter; it's entirely possible this is where I'll stop, and this thread will never prove relevant, but I'm asking in order to potentially future-proof this swap decision...
My dream is a sequential gearbox. With the apparent tranny space restriction forcing straight-cut only though, I'm thinking the whine will be too much [for other, "normal" people who might ride in my car, like my girlfriend, lol]. So instead, I'm looking at helical dog engagement in the H pattern; this could be close enough to sequential for me with the CAE shifter transforming 2nd->3rd and 5th->4th into straight shifts, negating what's normally high-money-shift-risk, making for quite a similar experience to that of a sequential. I've found a dog engaged helical gearset for the 02-07 STI- which brings us to this thread's question.

I did find this thread which seems to suggest this is possible, but I don't want to make the mistake of assuming my 2019 is too similar to a 2015, that JDM is too similar to USDM, etc. etc.
https://forums.nasioc.com/forums/sho...highlight=fl1p
[I looked up that transmission code and unless I'm wrong, it appears to be for years 01-02]

Another sign this is possible was from the Wikipedia on Subaru transmissions:
"Pre 2008 model year WRX STi 6MT versions utilizes a self-contained oil system with a trochoidal oil pump mounted in the rear of the transmission case. This capability was removed for 2008 and later years as Subaru elected to for a simplified splash/scraper lubrication system. However, the [pre-2008] oil pump-equipped 6MT version is still listed as the transmission of choice in the STi Group N parts system, even for the 2015+ model year WRX STi..."

Last year, I didn't know how a turbo worked; now, I alone have done all the work on my car from AOS to LSD, minus my pro tune- I'm proud of this, but I know my personal limits [and the limits of my living space] (both of which were met swapping the LSD in). If I do this, the goal is to be able to go to a reputable shop with at least a solid understanding of what it is I'm asking of them (e.g. "I need this transmission replaced with this, along with X Y and Z [flywheel, driveshaft, whatever] in order to future-proof putting in this gearset.").

I'm hoping someone here can clarify so that I can make an educated request of a shop.

Please remember this thread isn't for debating my rationale and choices leading to the title's question- I'm honestly very tired of explaining to people why I picked the WRX over the STI, and why I'm confident I want silly and completely unnecessary racecar bits in my car. I do appreciate input, but I'm really only here to see if anyone can answer a specific question, not to be abused for doing "dumb" things to my car. I know that even if it "can" be done, I need to then figure out if it "should" be done- but that's on me.
For example, yes, I still need to take into account the longevity of dogs over synchros if I decide to do this silly thing- but that's a different question for a different place.
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Old 04-03-2021, 05:28 PM   #2
snow_bound26
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You need to discuss how you want to use the car to really dive into a topic like this. Just simply stating 02-07 STi gears has a lot of variables. There are JDM non-DCCD gears, JDM DCCD gears, 04-06 USDM gears, 07 USDM gears. On top of that there's variations in the rear diff being 3.54 or 3.9 as some of the transmissions were 1.1:1 and others were 1:1. There's also helical diffs, Suretrack diffs, plated diffs to consider.

So why do you really want to do this? As in, what are you going to get out of it? Rambling on about wanting a sequential trans doesn't really tell us anything other than you have money to burn and don't mind a crap load of maintenance.

Can it be done? Sure, throw enough money at anything and it can be done. But it seems like a lot of work when you could just rebuild your current trans with some PPG gears and get that fancy shifter you're talking about and be done with it.
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Old 04-03-2021, 08:43 PM   #3
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Well I definitely do want to swap to an STI trans for the front helical and the DCCD (already have a clutch rear I love, but might have to change things or ditch it during the swap), but yeah simply buying custom gears from someone like PPG would definitely be ideal- I'm just not sure I can.
I reached out to them recently (earlier in my research, partially asking them about daily-driving straight cuts, etc.) and I did mention custom gears in the email, but their conclusion was "I would keep having a hunt around and see if there is another manufacturer that can supply a kit better suited to your needs". Actually, going back over their response, I'm not sure they even really addressed my proposition of custom gears (my email was pretty long)...maybe I should clarify with them what they can and can't do.

It was after that, that I found the following "02-07" gearset from Albins:
https://www.vividracing.com/albins-s...-p-152847.html
[these ratios are why this would be suboptimal- I don't really want a 6th gear with a lower top speed than my current 5th! Lol]
It has no additional information beyond "02-07" on what transmissions the set fits in; and when I tried to ask Albins directly if they knew if this gearset fit the newer transmissions, they simply said they didn't know...maybe I should ask them for transmission codes which the gearset is confirmed to fit with?

Why do this? Because racecar.
This is what I do; I dive deep into hobbies even if I don't plan to stick with them for life, acquiring/creating some weird manifestation of the hobby subject material everyone told me I would hate, that I proceed to absolutely love, lol. If I decide on it, it'll be the right decision- but I haven't even decided yet. I definitely don't want an absurd amount of maintenance; like I said, I do still need to clarify what kind of servicing I would expect- I'm waiting on an email from PPG on that topic right now actually.

Last edited by VeteranNoob; 04-03-2021 at 08:56 PM.
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Old 04-04-2021, 04:41 AM   #4
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Default Is it possible to use 02-07 STI gears with a 2019 WRX [involving transmission swap]?

"Because race car" is not an answer to how you plan to use the car. As mentioned there are many different ways to use said "race car".

Call Andrewtech Automotive. They are one of the best when it comes to Subaru transmissions and what options you have. There's a reason why you really aren't getting any answers here. And when you do call them, give concise, real answers. "Because race car" won't get you very far.
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Old 04-04-2021, 08:08 PM   #5
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Well I consider how I plan to use my car irrelevant to the question. I'm aware of other issues to consider like gear ratios, dog engagement longevity, adjusting shifting habits, etc., but my intentions are to make my requests for input as straight-forward as possible when involving others- asking non-open-ended questions without unnecessary context.
Theoretically that's doing forums "right", you know? Breaking up an idea into multiple questions of "Is this possible?", "What are the consequences?" and researching on my own instead of posting a single lazy and vague thread... But I suppose there's no getting around people raising concerns when they lack context- after all we do live in a world where many people are dumb enough to do some pretty silly things because they didn't ask "should" after discerning "can", then go on to regret it

I suppose I could've typed up everything that might address common concerns, but there's two reasons I didn't: 1) Some questions this thread's relevance depends on aren't answered yet, and 2) I have a habit of typing waaay too much, to the point where no one reads my posts

On that note, you asked for it:
This is my "daily" driver; I work from home so I go multiple days without driving at all. My primary motivation to convert my car to sequential [or 'close', in a sense] truly comes from nowhere other than "it's cool". I will be taking my car to some casual rallycross, but it will be purely for fun, not pushing any limits / risking serious damage (if that means driving 20mph, so be it)- if I want to push, I already know what beater car I'm buying. I really love involved driving experiences and being in control of everything the car does. In racing conditions, the clutch is often more annoying than useful with no reason a human should need to control it [proven via modern sequentials tuned for down-shift blips and flat-foot up-shifts]; I'd absolutely love even just having the option to eliminate using it at my fingertips, even if I almost never do. On that note, I drive like a grandma 90% of the time- so I'm hoping dog engagement using the clutch most of the time results in viable maintenance for me. I do still want to be able to [somewhat] comfortably drive my car long distances (though, damn is the road noise already kind of nuts in this car) with solid mileage; so ideally I'd keep 5th and 6th ratios about the same as the 2019 WRX, (which is why custom gears would be great). I definitely want 1st-4th to be shorter (well, primarily 3rd and 4th) I'm already super happy with a conservative 300WHP; I think eventually I'd like to bump that up once more, but shorter "fun time gears" will already make the car faster where I want it, and I don't worry too much about HP numbers. This WRX will not become a full on project car anytime soon- that will be the rallycross car if I do end up buying one to toss around recklessly. Pretty much everyone vehemently discouraged me from putting a clutch LSD in my WRX (including the shop that tuned my car- and they are all very smart, highly respected guys)- that LSD is probably my favorite mod I've done yet.


Aaanyway thanks for the tip! I'll reach out to em.

Last edited by VeteranNoob; 04-04-2021 at 09:26 PM.
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Old 04-12-2021, 02:18 PM   #6
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https://www.facebook.com/AndrewYatesAutomotive is the Andrew you wish to contact as Andrewtech Automotive is now something different as Andrew left. Not saying Andrewtech is bad, but the Transmission brain AKA Andrew is gone and is doing his own thing now.

Your questions are all over the place which means you haven't read the post titled Transmission FAQ. https://forums.nasioc.com/forums/sho...d.php?t=665334 and you might as well read https://forums.nasioc.com/forums/sho....php?t=1126026 while you are at it.

Any 6MT will bolt into your car. Any 5MT will bolt into your car. You can swap whatever gears designed for your transmission housing into that housing. You can swap whatever front or rear differential you like though things are trickier with the center. There is no "sequential like" transmission. You have:

1. Sequential.
2. Synchro AKA normal engagement
3. Dog engagement
4. Helical AKA quiet gears
5. Straight cut gears

You need to figure out what you want. If you drive like a grandma 90% of the time, buying something with horror show drive-ability is nutty. I drive like a good Christian boy. And I have a PPG helical synchro 5MT with a PPG torsen front differential and a Cusco 1.5 way rear differential and am considering a new 12kg center differential. Any normal human can drive my car in terms of the transmission with zero instruction and zero drama.
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Old 04-15-2021, 12:51 AM   #7
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Thank you!

I mean, I only ever had one question :P though I certainly have little experience with working on cars, so it's probably pretty uninformed. I do actually know quite a lot about transmissions and diffs- just in a theory/classroom way, not in a way that would help me discern if X car part fits with Y car (just because I have no idea what kind of nuances I'm unaware of).

On that note, sure, a transmission either is sequential, or it's not, but tell that to my inner child who's driving this potential endeavor he's convinced the CAE shifter [which self-centers, allowing for straight shifts 2nd->3rd, 3rd->4th, 5th->4th, and 4th->3rd] paired with dog engagement would make for a pretty similar experience to a sequential.
And I mean...technically there are products on the market that "identify" as "sequential" conversions, when they just place an intermediary between a standard H pattern box and a "sequential" lever- which kind of muddies the water as well.

With your help, I'm quite close to figuring out what I want!
I know this would be crazy for most people, but for me I think I might love it- as mentioned, a big reason being how rarely I drive.
Honestly if I had a commute in traffic, I don't even think I'd drive a manual...


On the main topic:

Albins got back to me saying they don't have transmission codes which the gearset is compatible with- only that it "suits pre 2007 STi 6 speed".
I'm paranoid by nature, so that's concerning enough, but the site I found the product on already contradicts that, stating "02-07".
According to my service manuals, 2nd, 3rd, and 4th gears change, as does center diff (electromagnetic floating -> solenoid compression) from 2006 to 2007, so maybe that could explain the compatibility cutoff..? The 2006 gears match the Albins ratios, but only 1-4. I don't see any change in these ways from 2007 to 2008.
That said, characters 8-10 in transmission code change years 2005 to 2006 (6AA->7AA) and 2007 to 2008 (7AA->1MA), but there's little to no information on what that means (character #6 also changes, but it doesn't seem to be meaningful according to the code definitions).
Finally, I'm not even sure these manuals differ based on domestic market...

I want to believe I'm overthinking this, but Albins themselves didn't even give me a start date to go off of... It just doesn't seem like I have enough info to know what transmissions I can safely consider.

Last edited by VeteranNoob; 04-15-2021 at 01:10 AM.
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Old 04-18-2021, 05:18 PM   #8
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Oh I forgot to mention too: That Transmission FAQ list of gear sellers might prove super helpful, so thanks for that as well. Custom gears are still on the table, and I was having trouble finding sources that offer them.

Actually on that note: If anyone can speak on these guys, I'd be interested. They're the only place I've seen online [other than the Albins product] to explicitly say it's possible to put together a [at least partially-]helical dog kit for the STI transmission, but doing a bit of research, I came across some people saying they have quite a bad reputation- but it was controversial...
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Old 04-21-2021, 10:22 PM   #9
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Custom ratios will be enormous in terms of cost and lead time. Its really NOT the way to go. A better route is different gears hedged against different final drives hedged against different tire diameters and differentials to change the drive characteristics. Using the calculators in the Transmission FAQ, you can figure out what's close to what you want and make it happen.

For example, I have one size smaller diameter tires so my final drive isn't 3.9 but like 4.something (forget). Its one of the unknowns to many...smaller tires impact your final drive.

Or call Andrew and have a conversation. He's done more Subaru transmissions than everyone on the planet save for maybe 3 people.
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