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Old 01-19-2022, 08:45 AM   #1
Scooby Newbie
Member#: 487492
Join Date: Jun 2018
Location: Cape Cod
2005 Legacy GT

Default 15+ WRX 6MT into 05/09 Legacy/OB

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 3/8" 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.. 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 " 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 did not swap out the rear diff due to it being a LSD and having the same FD ratio as the transmission. ( 4.11 )

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..
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Last edited by Scottish881; 01-19-2022 at 10:53 AM.
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