Subaru Forester Sports XT, STi conversion thread

CPB

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The long term goal for this car has always been to eventually do a full STi swap. About a year ago slightly over 200k miles my wife's TD04 in her Forester XT was beyond bad with the turbo seal dead and shaft play horrendous, so we swapped in a used STi VF52 and my old OEM STi intercooler. The STi levels of power was great, but during the swap we knew the WRX transmission these come with wouldn't survive very long.

You can't just swap transmission, as the differential ratio is different to the center diff. Once you swap trans and diff, now you are on different axles. Those axles won't fit the hubs, then the rotors won't fit the hubs. So basically this snowballs to where you replace everything to STi components

Just a few weeks ago on her way to work she heard a "bang." 3rd and 4th gear were unavailable and some terrible noises were coming from the car. She limped it back to the shop, where I had the 92x Aero already taking up all my time. see here: https://www.rdforum.org/threads/109890/

The Saab was all wrapped up last weekend, so it was time to start taking apart the Forester.

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Just got done installing this turbo last year, now it has to come off the uppipe to clear the transmission. Slightly annoying, but wasn't the end of the world.

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This isn't supposed to be multiple pieces! The tail is actually just floating in the pic, I set it on there since I didn't have three hands. Guessing when 3rd gear went, the shock to the output shaft or twist bound on the rear case and caused the aluminum to shear. These parts didn't fly down the road, since the driveshaft has a collar, that was basically holding the free floating chunks until I removed it. That would explain some of the terrible noises.

Time to order a lot of parts.

Next Steps
-STi Pressure Plate/Flywheel/Clutch
-New Rear Main Seal
-STi U-joint steering knuckle (required to adjust the geometry, since the STi transmission will sit closer to the chassis)
-STi Transmission cross-member (Will sit close to the chassis, FXT has a 1" spacer vs the STi)
-STi Transmission
-STi Axles
-STi Driveshaft
-STi Differential
-STi Hubs
-STi Brakes
-iWire DCCD Controller
 

Randy at Radenso

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Good luck on the swap, I just did all of what you listed to my car.

FYI - iWire doesn't make the actual DCCD controller. I'd recommend MapDCCD for your controller and use iWire wiring for it.
 

CPB

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CPB

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1618840705986.png


I'd never skip replacing a rear main while the transmission is out, unless under time constraints like at a LeMons race. This one was already leaking a little, nothing that would cause clutch issues.

EJ rear main seals are a bit of a hassle, so I bought a tool for install. https://www.flatironstuning.com/asf-machine-rear-main-seal-installation-tool-ej

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Uses the flywheel bolts to press in the seal to the proper depth.

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All cinched up and perfect.

I installed the new sti flywheel, clutch and pressure plate, but realized the STi has more pressure plate bolts than the WRX. Waiting on more to arrive.

I still need to order the rest of the swap components, but wanted to tackle the transmission out items.
 

elantra04

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Fantastic project. Wish I had your skills! What type of power are you looking to make in the forester now?
 
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CPB

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Fantastic project. Wish I had your skills! What type of power are you looking to make in the forester now?
We haven't dyno'd it with the STi turbo installed, but other cars of similar mods (including my STi) and boost levels make slightly over 300whp. Nothing crazy, but it will do it reliably in a small package. Compared to modern cars stock turbo Subaru's are "tame."
 

Euurx

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I just came here to say.. YAY WAGON!
 

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