STI as a Donor

[mquam99]

Hello

This is my first post. I am in the process of finding a donor for an 818C build and have one question. The FF website says the STI is not an option for a donor, but I see a lot of references to folks using the STI. Can anyone clear up for me if the STI is a viable option?

thanks

[Innkeepr]

I wondered myself at the beginning of my build. Aside from some suspension parts that my differ, now FFR has a STi 6 speed adapter. The only parts I read that people are using are the brakes ( not needed in a 1800 lb car ) the motor & trans (ecu & harness)
The cost of a wrecked STi is beyond belief. Unless you have one already, I'd look for a WRX with a bad drive train.
Other option ( what I did ), I found an 04 RS with high miles in good shape. Then I bought an ej207 with a 5sp for $2500.
I plan on replacing a lot of the donor stuff with new, I learned a valuable lesson building my Cobra- almost all donor parts have been replaced over the last few years.

Check the forums as I believe this has been addressed by others with the same questions

http://thefactoryfiveforum.com/showthread.php?6828-STI-donor-possibility-hear-me-out

http://thefactoryfiveforum.com/showthread.php?13468-Using-an-06-STI-Donor-Car

Best of luck & welcome to the madness.
"E"

[mquam99]

thanks for the reply, that helps a lot. Even the cost of a wrecked WRX can be pricy so I will take a look at this option. Thanks again, and I am sure I will be asking more questions as I go along.

[Hindsight]

A few have done it so hopefully they will chime in but all the 6-speed stuff you need won't come in the kit; you'll have to purchase it extra from FFR but as Innkeepr said, the parts ARE avaiable (for an extra fee). You'll have to modify the rear frame to get the 6-speed to fit. I think the axles are different so you MIGHT have to have custom axles made but others have been through this already so search the forum and you'll see (Sponaugle did it and Aero STI is working on it currently - just search for 6 speed). You have to modify the FFR front spindle brackets to get them to work with the larger STI spindles. I think Sponaugle detailed this in his build thread as well.

[STiPWRD]

Here's another useful link. I think Kurk818 was one of the first to use an sti donor.

http://thefactoryfiveforum.com/showthread.php?11695-who-will-be-the-first-to-try-putting-the-sti-6-speed-tran-in/page4&highlight=kurk818+sti

[Kurk818]

A few have done it so hopefully they will chime in but all the 6-speed stuff you need won't come in the kit; you'll have to purchase it extra from FFR but as Innkeepr said, the parts ARE avaiable (for an extra fee). You'll have to modify the rear frame to get the 6-speed to fit. I think the axles are different so you MIGHT have to have custom axles made but others have been through this already so search the forum and you'll see (Sponaugle did it and Aero STI is working on it currently - just search for 6 speed). You have to modify the FFR front spindle brackets to get them to work with the larger STI spindles. I think Sponaugle detailed this in his build thread as well.

Pretty much what you stated. Frame modification is not required if you use the FFR supplied spacer blocks to lift the back of the transmission to clear the frame. Reusing the OEM STI axles will put your car approx 3/8" wider than a standard WRX. This can be corrected with the right offset rims.

If you decide to keep ABS like i did, that throws another wrench into the mix that a bit more to explain.

Plan on dealing with more wiring as a result as well if you plan on dieting it. Im pretty sure iWire has a solution for that tho.

[Hindsight]

Kurk, does lifting the transmission cause it to be even more forward-tilted than the 5-speed already is in the 818? I would worry about transmission oil not getting to the rear of the case with any more tilt than is there already.

[Kurk818]

Kurk, does lifting the transmission cause it to be even more forward-tilted than the 5-speed already is in the 818? I would worry about transmission oil not getting to the rear of the case with any more tilt than is there already.

You are correct. It pitches the whole powertrain forward. That why i chose to modify the frame.

[Aero STI]

It's noteworthy that the adapter for locking up the DCCD that factory five offers only works on '06 or newer 6 speeds. You can buy a much more expensive adapter from NZ that handles all of the non-split case 6 speeds. Either option seems unnecessary to me. Just weld up the spiders and save $300-$1000. That's what I'm doing.

[Zach34]

It's noteworthy that the adapter for locking up the DCCD that factory five offers only works on '06 or newer 6 speeds. You can buy a much more expensive adapter from NZ that handles all of the non-split case 6 speeds. Either option seems unnecessary to me. Just weld up the spiders and save $300-$1000. That's what I'm doing.

Are you welding a 2005 center diff.......... or one that looks like this?

50130

If so, do you have pictures of how you welded it?

There's not a great way to get at the spider gears to weld this one. You could sort of tack them in a few places, but there was enough play in the spider gears that weld shrinkage would likely result in some of the teeth carrying all of the load instead of having it equally distributed.

Since a failed center diff could ruin the transmission, I decided to get the Possum Bourne adapter and sell the center differential to make up some of the cost. The other model center diff looks like it would be a better candidate for welding (or just use the FFR adapter, which won't work on the above center diff).

[Aero STI]

Are you welding a 2005 center diff.......... or one that looks like this?

50130

If so, do you have pictures of how you welded it?

There's not a great way to get at the spider gears to weld this one. You could sort of tack them in a few places, but there was enough play in the spider gears that weld shrinkage would likely result in some of the teeth carrying all of the load instead of having it equally distributed.

Since a failed center diff could ruin the transmission, I decided to get the Possum Bourne adapter and sell the center differential to make up some of the cost. The other model center diff looks like it would be a better candidate for welding (or just use the FFR adapter, which won't work on the above center diff).

I'm welding up a '06+ DCCD, so the adapter is available. However, see no need for the adapter if you have a welder. I'll provide pictures when I get a chance.

I looked at pictures of the earlier DCCD and welding that seemed very feasible, but if you have first hand knowledge that says otherwise that's important. My 6 speed came out of a JDM Forester STI. It was supposed to come with a viscous center differential, but the scammer that sold the transmission took it out. The viscous unit is definitely weldable and only costs $500 brand new, but there is a potential hitch with the drive transfer gear having the right length. From what I can tell this part is fine with the '05 or older, but not the '06 or newer. Even if a new drive transfer gear is required it's still a less expensive option than the Possum Bourne adapter.

Subaru Part 38913AA112:
http://www.importcarparts.co.uk/pictures/38913AA112-SUBARU-IMPREZA-6-SPEED-NON-DCCD-CENTRE-DIFF.jpg

[Pearldrummer7]

Echo'ing what everyone else said: it's going to cost a lot of money but is doable. You do get the better control arms thay way, at least. If you have a wrecked STi, use it! If not, I would at least cross shop WRXs