Converting a Subaru STI 6 speed for Mid-Engine use

[@subarugears]

Thanks for your review and comments, we've taken them on board. Double checked that all lockout holes are reemed to 13mm. We will include the shift rod seal and nice hardware bolts with future kits.

[@zwickauracingworks]

That would resolve almost all of the issues I had to be sure. I ended up buying flange headed bolts from McMaster that make it look almost stock. The shift rod seal did come out very easily tho with no damage so not much of a problem to be sure. Thanks for reaching out with an update tho, much appreciated!

[@pirateradio1926]

Bro I have watched all of 26 seconds of this video and am already subscribed with all notifications. I know immediately several facets of your character, from the line "I am building an Auto union type C replica." Clearly you have substantial skill, or Interest and willingness to learn. You understand that all of these machines regardless of how exotic were built by man, and as you have the same human capacity they do are able to solve any problem through research and resourcefulness. And you have an appreciation of the historic significance of this vehicle. You haven't even pitched the "like, share, subscribe" line and I have done all three. Please keep the project updates coming!

[@zwickauracingworks]

Thank you so much for the extremely kind words, I will definitely try my best to live up to the praise!! The subscribe pitch is always at the end, if someone makes it that far in the video I feel it's more appropriate to ask than just saying "trust me, you'll want to subscribe because this is awesome" before you've actually decided if it was your cup of tea.

[@joshuaszeto]

You sir, are a God send. I occasionally do work at the Porsche dealership and there is an all but abandoned 986 Boxster that I have been really contemplating about buying but that 5 speed would grenade the moment I swap anything more powerful than the 2.7 in there. I even looked up a few years ago if this could be done but nobody could give me a straight answer. You may have solved all my questions. Subbed!

[@zwickauracingworks]

Fantastic to hear that it has useful info for you! A large portion of why I make any videos is to try and help spread information and knowledge, both sending it out and getting it back via comments here.

[@seanhiggins704]

Awesome. Ive got a jdm automatic sti tranny that i want to do this to. Hope the back and center diff section is the same.

[@zwickauracingworks]

I honestly don't know enough in depth stuff about Subaru stuff to know. I'd look for an old forum post somewhere, if it's been in a Subaru someone's tried it!

[@andrewstuckey7736]

I live in Australia we do have 1/2inch drill bits

[@zwickauracingworks]

I thought so because I love watching Cutting Edge Engineering and you see him using US fasteners and such when necessary on repairs.

[@sandymilne224]

You have to do a follow-up video of the mid engine car when running.

[@zwickauracingworks]

It will definitely be recorded, been working with the guys at Haltech on setting up a standalone ECU.

[@xxZigxx]

wow that Mr. Sark shirt is a blast from the past! love this build too! cant beat a v12 and a 6 speed proper trans!

[@zwickauracingworks]

It sucks he doesn't upload to KZbin anymore but I still love his content!

[@xxZigxx]

@@zwickauracingworks yeah for sure! After I saw this I had to look up a best of Respawn Mailbag with Sark and APL.

[@zwickauracingworks]

every once in awhile I will go back and watch "The Legend of Mr Sark Part 2" which is mostly Respawn with APL and it's still hilarious today. I have timestamped some of the my favorite clips there so I can go back to those specifically lol

[@JimBrodie]

Props for the Elbonia shirt. =]

[@zwickauracingworks]

Everyone's favorite unluckiest/most corrupt country ;)

[@DatBoiOrly]

Personally what i thinks happened with that hole is they used an old reamer bit to drill it since they eventually wear down and become smaller diameter especially when working with aluminium since aluminium oxide is used as an abrasive so it kills them quicker

[@zwickauracingworks]

That's definitely possible, I didn't get much info back from them to know for sure. I will have an addendum video coming soon to show the finishing work to the tailhousing though.

[@bobolulu7615]

Considering where the output shafts are on the front diff, the crownwheel must be farking small!

[@zwickauracingworks]

Is crownwheel what is known as the ring gear in US parlance? It is fairly tiny even with the bulge below the rest of the case to be sure!

[@bobolulu7615]

@@zwickauracingworks Yup, ring gear

[@Dreadz530]

I had never really thought about it the drivetrain was any different but I guess being that they are AWD instead of 4wd they don’t have regular differential setups. I guess I had just figured they had a front rear different up at the axels. I hadn’t ever imagined that the differentials were basically integrated into the transmission package. Guess it makes sense for rally driving where you’d want as much clearance as possible and saves the headache of trying to shoehorn a differential under the motor and between the bulkhead for the independent suspension setup. I’ve been seeing the guys taking the square body Chevy trucks and running them 4wd with a LS engine and they obviously hook up amazing on some of those shitty streets. I was thinking about how you’d go about getting the front gears and all that and the ground clearance on the lower cars but if they were able to be located into or near the transmission setup that would make a much better install. I’ve been debating on trying out a AWD/4wd 99’-04’ mustang with twin 70mm snails and a newer L8T engine swapped. That’s the new bigger gas engine from the Chevy 2500s it’s an Iron block LT based engine that’s also a 6.6L and like all the engines in that family all the Corvette/Camaro stuff is interchangeable so you are getting a nice little jump up from the 6.2L aluminum based blocks

[@zwickauracingworks]

a lot of awd longitudinal engine cars integrate the front diff into the engine oil pan with one axle traveling through the pan for better ground clearance and the differential nestled up under one bank of the engine(one side of a V8 in Mercedes and under the leaned over inline 6 for BMW are good examples. Trucks with IFS also have a similar setup, the front diff is usually just a more compact axle housing though that bolts into the front of the frame(look up the GMC Syclone for a great example!)

[@jodyjohnstein]

Every fwd trans is a transaxle lol

[@ronnelson7828]

Great video. Will be paying close attention to this project. What year/model vehicle does this transaxle come from? Instead of reaming out the hole, it would be possible to turn down the part in a lathe to fit the new back cover.

[@manxman8008]

it's hardened steel

[@zwickauracingworks]

I don't remember the exact year but it is from a Legacy Spec B, very similar to the STI unit except open diff and slightly different gear ratios. As manxman said, the pin is hardened so turning it would be extremely difficult without a very rigid machine and carbide tooling. A reamer is much cheaper and the aluminum is very soft and will not be nearly as much work to alter. Thanks for the questions!

[@jeremysarver5094]

Great job so far! What’s the latest on your project?

[@zwickauracingworks]

Been absolutely slammed with work and other stuff but I have new videos coming soon! Thanks for being so patient!!!

[@ScottBerger-b1q]

Could you have just modified the original rear cover?

[@kurtbilinski1723]

Curious how this holds up. Transmission gears are rated by how much torque they can handle, not horsepower. Did you confirm with independent sources that the STi transmission will hold up to the much higher torque? Of course, it's the torque through the transaxle, meaning that if you use skinny tires, it'll hold up fine. OTOH, using sticky slicks and it'll probably grenade at the first clutch drop. I highly suggest talking to people who don't have their hand in your wallet regarding transaxle selection. There's a reason why transaxles rated for V8s and such are well over $10K.

[@zwickauracingworks]

I am also curious, I plan on hopefully going to some of the drag n drive events like Drag Week or Rocky Mountain Race Week which would really benefit from some slicks hooking up. That will definitely stress the trans more even with the extreme low weight. The V12 will also make a substantial torque figure but I don't think it will be that bad considering it's only 5.5L iirc. We'll both have to wait and see, unfortunately.

[@joshmanwaring3848]

It makes me wonder if you could take a fwd transaxle and convert it to a rear engine rwd

[@ranjitsian5481]

Good work 👍

[@zwickauracingworks]

Thank you! Cheers!

[@Popes_Projects]

$1100usd is a lot considering you could buy a tig welder for less and simply use parts you already had like I did. Nevertheless good work and a good video 👍

[@zwickauracingworks]

I did that on my first conversion of the WRX trans. I was hoping this would turn out nicer, shorter, and more reliable. I feel like the differential eliminator is much better being made as a single piece vs welding up a factory diff, especially given the power output the V12 should make. It's just a shame it was so shoddily manufactured.

[@Popes_Projects]

@@zwickauracingworks I guess we'll find out, my setup should have more power but I'll know soon enough. Mine just uses two pieces welded together from the center diff.

[@manxman8008]

great video thx for this

[@zwickauracingworks]

Glad you liked it!

[@timothymarshall2722]

Have you ever done a automatic transmission out of a 2005 outback before. Or know anyone who has?

[@zwickauracingworks]

I haven't, never heard anything good about Subaru automatics honestly

[@stuart207]

Nothing like the smell of gearbox oil, on your clothes, shoes and under your nose where you wiped your face 😂

[@zwickauracingworks]

It's only surpassed by the differential friction modifier stuff in the tiny bottle, the smell of that stuff was designed by satan himself haha!!

[@5150TJT]

Few companys doing this in Australia, these guys are not the first to design this, price is bs,...

[@zwickauracingworks]

Didn't know that when I ordered this, it was the only one I had seen offered. Agree the price is way high especially considering the quality(or lack thereof tbh)

[@ylwgtr]

Which ones are they mate? The only one I could find was for the earlier gearbox not the sti 6 speed

[@beckers1330]

Pretty sure this is a legacy gearbox, more or less the same as the STI box

[@zwickauracingworks]

Excellent eye or great guess, this is a Legacy Spec B box. Only difference I'm aware of for this year is it having an open front differential which is supposed to be stronger than the LSD in the STIs(I am not a Subaru expert tho, so there could definitely be more)

[@beckers1330]

The gear ratios are also different.

[@veganbutcher3448]

How much hp can it handle after this conversation.

[@zwickauracingworks]

I do not know for certain, but I would guess very similar to the stock unit. These STI 6 speeds are renowned for being basically indestructible and thats in a full weight Subaru. This car should be well under 2000lb when complete so the trans is basically the strongest link in the powertrain currently(less vehicle weight = less stress on the trans).

[@schorantayuen8851]

can it be used with 2jz?

[@zwickauracingworks]

with an appropriate adapter, absolutely!

[@bluejayfabrications2216]

1100usd gees thats steep

[@zwickauracingworks]

definitely would not do it again lol!

[@JorgeRodriguez-xv9vo]

And No instructions

[@zwickauracingworks]

Definitely would've been nice to have even a minor insight on assembly!