Transmission Swap/Compatibility

PittISDTech39 · 05-20-2020, 08:42 AM

Hi All, long time lurker, first time poster here.

I know there are a few threads around about this topic, but I haven't been able to find enough information to make me feel confident purchasing a used transmission. I have an '09 Impreza 2.5I (non-turbo) wagon that has a failing 5 speed tranny and center diff. I've read a couple different things that have said I can drop any subie 5spd MT in as long as the final drive ratio matches that of the rear diff and that it matches if its a Push/Pull type clutch. Using the Rallispec chart, Ive found that my trans (TY758VC1AA) has a FD of 3.90, but I don't know if it's a push or pull. Am I missing any other pertinent info that would make a difference before pulling the plug on a used tranny? And are JDM transmissions compatible with our USDM motors (EJ253)? I've found a few JDM transmissions with the correct final drive that are alluring due to their low mileage and they tend to be less expensive. Thanks in advance for any input!

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Jedi03 · 05-20-2020, 11:33 AM

go 6 speed an get the rear end to match!

snow_bound26 · 05-20-2020, 01:08 PM

You have a push type clutch. You can tell by looking at the slave cylinder. If the piston points at the engine then it's a pull type. Points toward the firewall than push type.

As for FD, you have to find out if your trans is a 1:1 or a 1.1:1 (more common). 1.1:1 has a 3.54 rear diff for a 3.9 FD.

PittISDTech39 · 05-21-2020, 07:56 AM

Quote:

Originally Posted by Jedi03

go 6 speed an get the rear end to match!

Wouldn't that be nice!

PittISDTech39 · 05-21-2020, 07:57 AM

Thanks Snow! I'll start trying to figure out if it's 1:1:1.

Samurai Jack · 05-23-2020, 11:10 AM

TY758VC1AA

US Impreza 2008
You have a Transfer Ratio of 1.0 and a Final Drive of 3.90.
That means you need a Rear Diff with a 3:90 ( R160 ) to match.

You have to match the transmission to the rear diff, like I showed above. All the info is on the Rallispec chart you looked at.

Can you use any USDM or JDM transmission ( 5MT or 6MT ) with a USDM motor?
The answer is "yes you can".

If you go to a 6MT, then you will need a 6MT clutch, 6MT flywheel, 6MT driveshaft, whether or not you use your current rear diff ( R160 ) or get a 6MT ( R180 ) rear diff.

PittISDTech39 · Yesterday, 05:58 PM

Quote:

Originally Posted by Samurai Jack

TY758VC1AA

US Impreza 2008
You have a Transfer Ratio of 1.0 and a Final Drive of 3.90.
That means you need a Rear Diff with a 3:90 ( R160 ) to match.

You have to match the transmission to the rear diff, like I showed above. All the info is on the Rallispec chart you looked at.

Can you use any USDM or JDM transmission ( 5MT or 6MT ) with a USDM motor?
The answer is "yes you can".

If you go to a 6MT, then you will need a 6MT clutch, 6MT flywheel, 6MT driveshaft, whether or not you use your current rear diff ( R160 ) or get a 6MT ( R180 ) rear diff.

I appreciate this info! I initially missed the T.R. column on the Rallispec chart but was able to pick it out eventually. The other info I was uncertain about was the rear diff, because that info is missing on the chart for this tranny part number, so you were able to identify it for me! I was able to find a low mileage JDM transmission that should work from Sunshine State JDM down in florida with all your help. Thanks again!

05-20-2020, 08:42 AM	#1
PittISDTech39 Scooby Newbie Member#: 405192 Join Date: Oct 2014 Location: Pittsburgh Vehicle: 2009 Impreza 2.5i white	Transmission Swap/Compatibility Hi All, long time lurker, first time poster here. I know there are a few threads around about this topic, but I haven't been able to find enough information to make me feel confident purchasing a used transmission. I have an '09 Impreza 2.5I (non-turbo) wagon that has a failing 5 speed tranny and center diff. I've read a couple different things that have said I can drop any subie 5spd MT in as long as the final drive ratio matches that of the rear diff and that it matches if its a Push/Pull type clutch. Using the Rallispec chart, Ive found that my trans (TY758VC1AA) has a FD of 3.90, but I don't know if it's a push or pull. Am I missing any other pertinent info that would make a difference before pulling the plug on a used tranny? And are JDM transmissions compatible with our USDM motors (EJ253)? I've found a few JDM transmissions with the correct final drive that are alluring due to their low mileage and they tend to be less expensive. Thanks in advance for any input! * Registered users of the site do not see these ads.

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05-20-2020, 11:33 AM	#2
Jedi03 Scooby Newbie Member#: 491095 Join Date: Sep 2018 Chapter/Region: SWIC Location: New Mexico Vehicle: 2009 STi Blue Blue	go 6 speed an get the rear end to match!

05-20-2020, 01:08 PM	#3
snow_bound26 Scooby Specialist Member#: 395793 Join Date: Jul 2014 Chapter/Region: Tri-State Vehicle: 2005 92x Aero Blue	You have a push type clutch. You can tell by looking at the slave cylinder. If the piston points at the engine then it's a pull type. Points toward the firewall than push type. As for FD, you have to find out if your trans is a 1:1 or a 1.1:1 (more common). 1.1:1 has a 3.54 rear diff for a 3.9 FD.

05-21-2020, 07:57 AM	#5
PittISDTech39 Scooby Newbie Member#: 405192 Join Date: Oct 2014 Location: Pittsburgh Vehicle: 2009 Impreza 2.5i white	Thanks Snow! I'll start trying to figure out if it's 1:1:1.

05-23-2020, 11:10 AM	#6
Samurai Jack Scooby Guru Member#: 21145 Join Date: Jul 2002 Chapter/Region: NESIC Location: Not in my own time Vehicle: 2002 Enemy of Aku	TY758VC1AA US Impreza 2008 You have a Transfer Ratio of 1.0 and a Final Drive of 3.90. That means you need a Rear Diff with a 3:90 ( R160 ) to match. You have to match the transmission to the rear diff, like I showed above. All the info is on the Rallispec chart you looked at. Can you use any USDM or JDM transmission ( 5MT or 6MT ) with a USDM motor? The answer is "yes you can". If you go to a 6MT, then you will need a 6MT clutch, 6MT flywheel, 6MT driveshaft, whether or not you use your current rear diff ( R160 ) or get a 6MT ( R180 ) rear diff.