Jump to content
LegacyGT.com

15+ WRX 6mt into 05/09 Legacy/OB


Scottydunno

Recommended Posts

Here's the scoop. This is probably one of the easiest trans swap any of us could do to our cars and also update/upgrade them a little. Here's what you need for the swap.

 

1. 15+ WRX transmission and matching FD rear diff.

2. Shifter assembly, cables and hardware for said transmission.

 

That's it!

 

You can reuse your clutch, throw out bearing, pilot shaft bearing, clutch hydraulics, front axles, driveshaft, rear axles.

 

The obvious first step is to acquire the parts.

 

2nd. Remove old the old transmission.

 

3rd. With the shifter out, remove the 4 bolts that hold the metal plate/rubber grommet for shifter area. Also the 2 screws that secure the center console.

 

4th. Disassemble the new shifter assembly. It should be 3 parts.

4a - bottom cover ( 4 nuts )

4b - shifter cable box ( 4 nuts to bottom of shifter )

4c - the shifter itself.

 

5th. By now you should notice that the 4 holes that go through the shifter also match the 4 holes that once held the old metal plate/rubber grommet. Flip the shifter upside down, with the studs facing you. Use a piece of cardboard or something to make a template for those 4 studs.

5a - using the 2 top through holes as a reference point, make the template for the studs. ( the 2 top in reference to the 2 holes closest to the firewall. )

5b - drill the additional 4 holes for the studs to go through the trans tunnel. I started with 5/16 bit, then enalrged to ⅜" in diameter to ensure they go through.

5c - the lower right hole on the trans tunnel you just drilled is very close to the original opening. I ended it up making it a notch so that the last stud will go through.

5d - you should've also noticed by now that the shifter assembly won't exactly fit unless you "clearance" the right rear corner.

 

6th. Set the shifter assembly into the car attop the trans tunnel. It doesn't sit flush. I'm sure 10+ years of car design had something to do with that.. [emoji848] anyways, set it relatively level and bolt it down evenly. Of course you're gonna need longer bolts. 8mmX1.25 bolts, I forget the length but figure about ¼" longer than the ones you took out from there originally. Before you tighten down the shifter, grab that metal plate with the rubber grommet. Cut that bracket ahead of the 2 lower bolt holes so that you can bolt it back under the shifter and reattach the center console back to where it was.

 

7th. Once bolted down, go under the car with the shifter cable box from 4b. Install that shifter box, and reattach the cables to the shifter. Once done, attach the metal cover from 4a.

 

Voila! New shifter installed. This part took me about 2 hours to do.

 

Time to swap stuff between the 2 transmissions.

 

1. Swap over the reverse light switch and the NPS switch. They go in the exact same position on the new trans as they were on the old one.

 

2. Swap over the sub harness for the switches. They even go in the same position on the new trans as the old one.

 

3. ( optional ) swap over the pitch stop mount. I did only to keep things simple.

 

At this point, replace the wear parts as needed, install new transmission. When routing the cables, they run down the driver side of the transmission, then up and over and attach to their respective spots. There is a retaining grommet that bolts to the trans that helps with routing the cables.

 

The original shifter bezel will fit with plenty of space for shifter movement. The boot will need to be changed because of the reverse lockout ring.

 

I've attached the most relevant pictures I took to help with understanding this whole ordeal. I have zero idea as to how to add these pictures between the paragraphs to make it easier to understand. Tapatalk doesn't quite make it easy to do that.. 94848a97d1b191461843f20b260b2f78.jpg7869c4a6dcf6a7be56e722b7de6279d2.jpge7067bd1a6932739b609272c2f936b5c.jpg6a46f0ba592ba5e09f6eefb1081ccf73.jpg4649ac425fa797e9c88ee3ce65c6d402.jpg10b0c41973ef6749d96877298f6c81c0.jpgac95c11a4d588318eb053eded43f03c6.jpgcb46de7d0779be5625f1040586032abd.jpgb6918344229aaf388c0c17ab5a9a7ce4.jpgd504fc818ce7dc04f0d4ce907990fcef.jpg2da2ff79d524035efbe0cd56dab80511.jpgd15f0d9f61d2411ce6e45f3a45a25bd5.jpga4f008f75ca0900109dc8bb68f3c5238.jpgce7af2f5752b828faabeb909f8ed1846.jpg

 

I forgot to add, since this transmission is a 4.11 FD, I kept my LSD 4.11 rear diff. Better than the stock open rear diff that came on those newer cars!

 

Sent from my SM-G996U using Tapatalk

Edited by Scottydunno
Link to comment
Share on other sites

  • Replies 107
  • Created
  • Last Reply

Top Posters In This Topic

It's odd that you didn't really see lower rpms at highway speeds. All of the gearing calculators show a 300 rpm diff at 75 mph and about 320 rpm diff at 80 mph when changing from 0.738:1 gearing to 0.666:1 gearing and a 4.11 rear diff.
Link to comment
Share on other sites

The shifter sits approximately ¼" taller than stock. It's not terrible, but definitely looks different in comparison to a double adjustable short throw..

 

I'll believe that math as far as gearing goes. It's the one thing I despise about electrical gagues. They can be off whenever and we'd none to the wiser!

 

Sent from my SM-G996U using Tapatalk

Link to comment
Share on other sites

What about size and weight? About same weight as our trans? Or noticeably heavier?
It's a little heavier, I didnt measure the weight or anything. Nothing noticeable while driving the car. The overall length is the exact same, hence why we are able to reuse the driveshaft.

 

The skinny about this trans is that's its a minimal external design change while the major changes were all on the inside. The last ⅓ of the trans is where you see the major changes externally. b6585efd812d33d5b1925a7bcc960289.jpg3f135d77cff9b5604428c24222c5f3d7.jpg

 

Sent from my SM-G996U using Tapatalk

Link to comment
Share on other sites

I believe it's the next evolution of the LGT 10-12 6mt which were from the diesel 6mt which is our splitcase 5mt with redone internals to fit a 6th gear. So, the dimensions of our 5mt are basically the same and I would imagine it's probably just 10-15lbs heavier vs the STi tranny that is reportedly 60-80lbs heavier (but is legit built heavier). It sure looks like you could get the 5mt blast plates to fit on these 6mt as well. That's what interested me about these 6mts is that I could reuse my newer axles, driveshaft, clutch, beefy fork, etc. Case wise the only difference I can see between the 15+ WRX 6mt and the LGT 10-12 are the case wings for the unique mounts for that gen LGT.
Link to comment
Share on other sites

I believe it's the next evolution of the LGT 10-12 6mt which were from the diesel 6mt which is our splitcase 5mt with redone internals to fit a 6th gear. So, the dimensions of our 5mt are basically the same and I would imagine it's probably just 10-15lbs heavier vs the STi tranny that is reportedly 60-80lbs heavier (but is legit built heavier). It sure looks like you could get the 5mt blast plates to fit on these 6mt as well. That's what interested me about these 6mts is that I could reuse my newer axles, driveshaft, clutch, beefy fork, etc. Case wise the only difference I can see between the 15+ WRX 6mt and the LGT 10-12 are the case wings for the unique mounts for that gen LGT.
It's definitely not 60+lbs heavier! My arms can tell you that! I took pictures of the associated wear parts in comparison to the parts that came off the 6mt. They all look identical and fit exactly the same. It really is a minimal design change/evolution.

 

Sent from my SM-G996U using Tapatalk

Link to comment
Share on other sites

So what is the purpose of this over a 5-speed if it isn't more durable (Surgeline tells me it isn't) and it doesn't give you lower RPMs on the highway? Your 5-speed go out?
Link to comment
Share on other sites

So what is the purpose of this over a 5-speed if it isn't more durable (Surgeline tells me it isn't) and it doesn't give you lower RPMs on the highway? Your 5-speed go out?
It will be lower rpms on the highway by 300ish rpm (depending on speed).

 

I think he said he really replaced because his 5mt had a lot of mileage, he got this for basically the same price as a used 5mt but with low miles. He's always wanted a 6mt but didn't need the beefiness of sti 6mt. There was also the big curiosity factor of it fitting.

Link to comment
Share on other sites

It will be lower rpms on the highway by 300ish rpm (depending on speed).

 

I think he said he really replaced because his 5mt had a lot of mileage, he got this for basically the same price as a used 5mt but with low miles. He's always wanted a 6mt but didn't need the beefiness of sti 6mt. There was also the big curiosity factor of it fitting.

You hit the nail on the head! That's exactly why I did it, other than the fact that 5th gear disintegrated.... Point of fact, fuel mileage is better! Normally when I have a stuck front caliper, I lose about 30-50 miles of range from full tank. I purposely drove from my work (20 min south of Boston) up to NH ( 70 miles) to pick up new H&R springs, then drove home to RI (85 miles). Mileage was the same as if I had no issues and with the 5mt.

 

Yes, I deal with crappy reman calipers.. just can't beat the warranty! Though brembos are in my future at this point.

 

As far as power handling goes, it's probably the same as the old 5mt, though I'd like assume a little better due to newer gear designs.

 

Sent from my SM-G996U using Tapatalk

Edited by Scottydunno
Link to comment
Share on other sites

Thanks for being the first to try this out! What a great option for those of us with older 5MT that don’t want to do a specB / STI style tranny swap. Just need to keep seeing the vape bro crowd wrecking their ‘15+ WRX’s so we have some supply! Wait, did I just say that? :)
Link to comment
Share on other sites

great work here man! You may have inspired me to do this to my tired 5 speed lol. I dont see myself selling off my car just yet and had turned down a couple offers on offerup.

Follow me on IG @chefodiycarguy

and @chefo.soriano

Link to comment
Share on other sites

Thanks for being the first to try this out! What a great option for those of us with older 5MT that don’t want to do a specB / STI style tranny swap. Just need to keep seeing the vape bro crowd wrecking their ‘15+ WRX’s so we have some supply! Wait, did I just say that? :)
I'm not the first. AFAIK, I'm like one of a handful that have done it. Probably first with a comprehensive write up.. there are a few posts about it, but not comprehensive enough to actually work with.

 

Sent from my SM-G996U using Tapatalk

Link to comment
Share on other sites

id be sitting right at 400whp so ill have to research more 15+wrxs from this gen and see how well the trans is holding up :cool:
Please chime back with info. I'm also curious as well.. the power goal I want to be at I know is more than doable on this trans.

 

Sent from my SM-G996U using Tapatalk

Link to comment
Share on other sites

glad this swap worked out.

 

Since this is still a split case like the 5mt, its not as power limited as it is torque limited. the 5mt could hold power, but was terrible if there was excess torque shock from launches, slam shifting, or pulls in OD gears.

 

If they make blast plates for this trans, that would be a worthwhile investment for people making over 400tq, or for those who like to launch the car.

Link to comment
Share on other sites

If the case really is similar to the 5mt and the bolts are in the same place, then the 5mt blast plates may fit.

 

once i source one..ill chime back in here to see if my blast plates do transfer over. im not in a rush to get my car back on the road but sure am excited to see how this pans out now.

Follow me on IG @chefodiycarguy

and @chefo.soriano

Link to comment
Share on other sites

if someone wants to mess around...this is the best pic i have when i installed it. would be sweet if the bolts do line up.
Would the pictures I put up help? I can send you the originals on my phone if that'll help.

 

Sent from my SM-G996U using Tapatalk

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



×
×
  • Create New...

Important Information

Terms of Use