Swapping a 07 sti transmission into an 05 sti

michav717 · 01-19-2022, 10:42 PM

I just acquired a good working 07 sti transmission and rebuilding it with and OS giken diff and spec b 5th and 6th to go in my 05 Sti.
I got a rear OS Giken diff as well. My question is, do I need to get different transfer gears as well either out of my 05 transmission or new ones like the IAG chromoly ones to get the correct final drive?
Thank you ***128591;

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snow_bound26 · 01-20-2022, 07:48 AM

05 is 1:1 ratio. I believe 07 is 1.1:1. Just sure the way you set everything up matches. So use all 05 ratios is the rear diff is for the 04/05 model years or use all 07 ratios if it's a rear diff for the 06+ model years.

Bumaa · 01-21-2022, 01:19 PM

Not related to your question but the 05>07 transmission.

05 was 65/35 power split, 06+ 59/41.

IMO the 05 was better unless you enjoy unsteer. Too many people couldn't handle over steer so Subaru made the car more soft on the newer models. Especially if you plan to track/autocross its night and day difference.

https://www.rallispec.com/downloads/...art_Public.pdf

Edit: I wrote it flipped its 35/65 & 41/59.

Bumaa · 01-21-2022, 01:19 PM

Not related to your question but the 05>07 transmission.

05 was 65/35 power split, 06+ 59/41.

IMO the 05 was better unless you enjoy unsteer. Too many people couldn't handle over steer so Subaru made the car more soft on the newer models. Especially if you plan to track/autocross its night and day difference.

https://www.rallispec.com/downloads/...art_Public.pdf

Unabomber · 01-22-2022, 09:06 AM

You are asking about a ratios vice who makes it. There's no need for the IAG version unless you are making OMG power or just want them to make your brain happy. You should be able to answer you own question by counting the teeth, based on a prior post 33 teeth is 1.1 ratio and 30 teeth is 1.0 ratio. Knock on wood, your current trans is 1.0 and your 07 trans is 1.1. So you can swap over your old 05 transfer gears or buy new to swap in. If swapping, consider rebuilding those with new bearings while its all open.

http://www.gearhack.com/myink/ViewPa...ission%20Chart

And be a cool guy and tape a note to the removed trans if selling explaining the transfer gear ratios so the next guy doesn't unknowingly blow it up. From a past post it will work for awhile before it grenades.

K3rm1tth3fr0g · 01-23-2022, 07:16 PM

Quote:

Originally Posted by Bumaa

Not related to your question but the 05>07 transmission.

05 was 65/35 power split, 06+ 59/41.

IMO the 05 was better unless you enjoy unsteer. Too many people couldn't handle over steer so Subaru made the car more soft on the newer models. Especially if you plan to track/autocross its night and day difference.

https://www.rallispec.com/downloads/...art_Public.pdf

Shouldn't the 05 understeer more not less since it's sending more power to the front vs the 06+ which is more balanced?

Why would the car with less power to the front oversteer more than the 06+?

snow_bound26 · 01-23-2022, 09:07 PM

Quote:

Originally Posted by K3rm1tth3fr0g

Shouldn't the 05 understeer more not less since it's sending more power to the front vs the 06+ which is more balanced?

Why would the car with less power to the front oversteer more than the 06+?

No the 04/05 STi was a 35% front/65% rear split. That's why I chose the 05, better torque split for the track and the helical front diff instead of the Suretrack that came in the 04. Easier to make the car rotate under throttle.

K3rm1tth3fr0g · 01-24-2022, 03:00 AM

Quote:

Originally Posted by snow_bound26

No the 04/05 STi was a 35% front/65% rear split. That's why I chose the 05, better torque split for the track and the helical front diff instead of the Suretrack that came in the 04. Easier to make the car rotate under throttle.

Ah I read it as the first number was the front split and second number was rear - I see now the guy in this thread just wrote it backwards and that's that threw me off.

michav717 · 01-29-2022, 02:18 PM

I’m putting a 2015+ steering rack into it as well hopefully that helps. I also have an older mono steering wheel that from a bug eye that I wrapped. Didn’t realize they were bigger until I put it in which kind of sucked. Hopefully the new steering rack will help. Kinda deep into the transmission swap to back out now lol.

01-19-2022, 10:42 PM	#1
michav717 Scooby Newbie Member#: 151736 Join Date: Jun 2007	Swapping a 07 sti transmission into an 05 sti I just acquired a good working 07 sti transmission and rebuilding it with and OS giken diff and spec b 5th and 6th to go in my 05 Sti. I got a rear OS Giken diff as well. My question is, do I need to get different transfer gears as well either out of my 05 transmission or new ones like the IAG chromoly ones to get the correct final drive? Thank you **128591; Registered users of the site do not see these ads.

01-20-2022, 07:48 AM	#2
snow_bound26 Scooby Specialist Member#: 395793 Join Date: Jul 2014 Chapter/Region: Tri-State Location: SLC and Lake Placid Vehicle: 2005 92x Aero Beige	Swapping a 07 sti transmission into an 05 sti 05 is 1:1 ratio. I believe 07 is 1.1:1. Just sure the way you set everything up matches. So use all 05 ratios is the rear diff is for the 04/05 model years or use all 07 ratios if it's a rear diff for the 06+ model years.

01-21-2022, 01:19 PM	#3
Bumaa Scooby Newbie Member#: 528059 Join Date: Dec 2021	Not related to your question but the 05>07 transmission. 05 was 65/35 power split, 06+ 59/41. IMO the 05 was better unless you enjoy unsteer. Too many people couldn't handle over steer so Subaru made the car more soft on the newer models. Especially if you plan to track/autocross its night and day difference. https://www.rallispec.com/downloads/...art_Public.pdf Edit: I wrote it flipped its 35/65 & 41/59. Last edited by Bumaa; 01-25-2022 at 07:26 AM.

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01-22-2022, 09:06 AM	#5
Unabomber 👏 Big Ron 👏 Moderator Member#: 18062 Join Date: Apr 2002 Chapter/Region: MAIC Location: I can save you a ton of cash Vehicle: on car parts so PM me b4 j00 buy	You are asking about a ratios vice who makes it. There's no need for the IAG version unless you are making OMG power or just want them to make your brain happy. You should be able to answer you own question by counting the teeth, based on a prior post 33 teeth is 1.1 ratio and 30 teeth is 1.0 ratio. Knock on wood, your current trans is 1.0 and your 07 trans is 1.1. So you can swap over your old 05 transfer gears or buy new to swap in. If swapping, consider rebuilding those with new bearings while its all open. http://www.gearhack.com/myink/ViewPa...ission%20Chart And be a cool guy and tape a note to the removed trans if selling explaining the transfer gear ratios so the next guy doesn't unknowingly blow it up. From a past post it will work for awhile before it grenades.

01-29-2022, 02:18 PM	#9
michav717 Scooby Newbie Member#: 151736 Join Date: Jun 2007	I’m putting a 2015+ steering rack into it as well hopefully that helps. I also have an older mono steering wheel that from a bug eye that I wrapped. Didn’t realize they were bigger until I put it in which kind of sucked. Hopefully the new steering rack will help. Kinda deep into the transmission swap to back out now lol.