FYI: TY75 6mt (Split Case) vs 5mt

mtcookson · 05-13-2025, 11:21 AM

TLDR: Skip to bottom for pictures of gear thickness differences.

I've been looking around for comparisons and haven't come across any yet so decided to post my findings on some differences I spotted between the TY75 6mt from a 2017 WRX and a TY75 5mt from a 2002 WRX.

To make a very long story much shorter; I was going to put the '02 WRX 5-speed into my H6 (non-R) swapped 2002 Outback for the .738 5th gear but, after a series of events (one that can be seen in the pictures, not caused by me

), I'm putting in the 6-speed.

First impressions before opening the 6mt were that the case definitely had more significant webbing to improve rigidity. Upon opening the case I quickly saw that the 6mt is NOT simply a 5mt with an extra gear, as I often see people say online. I was quite impressed at the significantly improved gear thickness of 1-3 and 5-6 also having slightly thicker gears. It was also interesting to find that reverse was now helical cut and synchronized.

These measurements I would consider as approximations as I was using calipers and had to eyeball a few.

Click link for picture of the gear:
TY75 5mt:
1st: 15.81mm
2nd: 13.22
3rd: 14 (by eye)
4th: 15.96
5th: 16.15

TY75 6mt (2017 WRX)
1st: 20.63mm
2nd: 17.77
3rd: 16 (by eye)
4th: 14.89
5th: 16.86 (by eye)
6th: 17.14 (by eye)

I know it's not going to be STi levels of power handling by any means but surely these will take some more power than the 5mt's. You still can't abuse them with clutch drops of course but just raw power handling should be noticeably higher. If some good "blast plates" are developed for it to add more case rigidity then power handling should improve slightly more.

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ether947 · 05-15-2025, 11:25 PM

Very interesting! Thanks for posting this. I assumed that the gears were the same size as well.

mtcookson · 05-17-2025, 08:19 PM

What'll really grind your gears (pun intended) is the '02 WRX gears are the same size as the gears in a FWD transmission from a 1994 Impreza 1.8 I have laying around.

05-13-2025, 11:21 AM	#1
mtcookson Scooby Newbie Member#: 47506 Join Date: Nov 2003 Location: USA Vehicle: 2002 Outback H6 6MT White	FYI: TY75 6mt (Split Case) vs 5mt TLDR: Skip to bottom for pictures of gear thickness differences. I've been looking around for comparisons and haven't come across any yet so decided to post my findings on some differences I spotted between the TY75 6mt from a 2017 WRX and a TY75 5mt from a 2002 WRX. To make a very long story much shorter; I was going to put the '02 WRX 5-speed into my H6 (non-R) swapped 2002 Outback for the .738 5th gear but, after a series of events (one that can be seen in the pictures, not caused by me ), I'm putting in the 6-speed. First impressions before opening the 6mt were that the case definitely had more significant webbing to improve rigidity. Upon opening the case I quickly saw that the 6mt is NOT simply a 5mt with an extra gear, as I often see people say online. I was quite impressed at the significantly improved gear thickness of 1-3 and 5-6 also having slightly thicker gears. It was also interesting to find that reverse was now helical cut and synchronized. These measurements I would consider as approximations as I was using calipers and had to eyeball a few. Click link for picture of the gear: TY75 5mt: 1st: 15.81mm 2nd: 13.22 3rd: 14 (by eye) 4th: 15.96 5th: 16.15 TY75 6mt (2017 WRX) 1st: 20.63mm 2nd: 17.77 3rd: 16 (by eye) 4th: 14.89 5th: 16.86 (by eye) 6th: 17.14 (by eye) I know it's not going to be STi levels of power handling by any means but surely these will take some more power than the 5mt's. You still can't abuse them with clutch drops of course but just raw power handling should be noticeably higher. If some good "blast plates" are developed for it to add more case rigidity then power handling should improve slightly more. * Registered users of the site do not see these ads. Last edited by mtcookson; 05-14-2025 at 02:15 AM.

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05-15-2025, 11:25 PM	#2
ether947 Scooby Specialist Member#: 297799 Join Date: Oct 2011 Chapter/Region: South East Location: Knoxville, TN Vehicle: 2003 WRX EJ207 version 8	Very interesting! Thanks for posting this. I assumed that the gears were the same size as well.

05-17-2025, 08:19 PM	#3
mtcookson Scooby Newbie Member#: 47506 Join Date: Nov 2003 Location: USA Vehicle: 2002 Outback H6 6MT White	What'll really grind your gears (pun intended) is the '02 WRX gears are the same size as the gears in a FWD transmission from a 1994 Impreza 1.8 I have laying around.