Subaru STI 6MT Teardown - Not a How-To

[joebush44]

After not finding much of any type of documentation (aside from the FSM) on tearing down the STI 6 speed transmission, I decided to throw something together as a reference for anyone else looking. After shredding 2nd gear in my transmission I've been motivated to trying to get the gear stacks out of the transmission myself, mainly to save on labor costs on the rebuild. This is not a fully inclusive how-to, but covers everything involved in removing the case and gear stacks. Hopefully it will be useful to someone!

I didn't document anything having to do with removing the transmission from the vehicle - it would be my assumption if you're looking to tackle this yourself, you're mechanically savvy enough to have gotten that far...

I didn't document my steps on removing the tail housing of the transmission, but IAG's instructions for transfer gear installation is a great reference (first 4 pages)...
https://www.iagperformance.com/v/vsp...-1000-1010.pdf

That leads me to this point. The trans is on the table and the tail housing and output shaft have been removed...

Note that this specific transmission is from an '07 USDM STI and should be similar to 08+ USDM STI. 04-06 are slightly different in that they still utilized an oil pump.

I set the case on a couple of 2x4's so there is clearance for the input shaft underneath (it protrudes from the transmission bellhousing about an inch).


Disconnect the diff electrical plug


Now the diff will just slide right off of the pinion shaft. There are 4 of these clamshell bearings that go on the snout of the pinion shaft, between the diff and the pinion shaft


You should now see this view (pinion shaft with diff removed pictured top (sleeping doggo optional))


Side view


Remove this roll pin


Roll pin removed


Remove snap ring and washer


cont...