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FlatironsTuning
04-03-2014, 04:18 PM
We just became a vendor here, and I thought I would make our first post one about the differences in some of the Subaru 5MT gear sets that are available. I did notice that you all ready have a sticky thread about the Subaru transmissions, but I thought I would start a new thread just to let everyone know that we are now an official vendor here. Mods, if you would like to merge this with the sticky, that is fine.

This is actually a post that we created a while ago, but the information is still current. This is also an article in our FAQ blog here. (http://flatironsrally.typepad.com/faq/2010/05/comparison-of-subaru-gear-sets-wrx-legacy-gt-sti-ra-and-more.html)

I hope this helps, and please feel free to ask us any questions you might have! Thanks for looking!

I just had to rebuild the transmission in my 2003 WRX, and put in an STI V.6 Gear set. In the process of doing so, I decided to compare the gears going out, and going in, and I thought I would post what I found.

First, I actually had a set of gears from a 2006 WRX from an install that we did a while back. The first thing I did was to compare the 03 2nd and 3rd to the 06, and as far as I can tell, they are identical. I an 100% sure about 2nd, and 90% sure about 3rd. The reason for this is that 3rd gear went out on the 06, so there are no teeth on the driven gear. However, the tooth count is identical, and the base of both gears is the same.

[Up-Date]5-24-2010

In terms of 2nd gear specifically, we actually had both the 2002 and 2003+ second gear on hand. Here is a picture that shows the difference:

http://i62.photobucket.com/albums/h112/Scubynubie/02-03WRX2nd001-MedLogo.jpg

As you can see from this picture, the later generation 2nd gear was definitley thicker than the 2002 2nd gear, but the gear teeth count, and thickness is identical. You can also see that Subaru put two notches on the top of each gear.

Some people say that the early production 03's actually had the 02 gears, but I am not so sure. the part # for the 2002 2nd is 32251AA700, and it was used in producton from Sept. 2000 through May of 2002. The part # for the 03+ started as 32251AA810, which supersceeded to 32251AA820 and was used in production from April 2002 through June of 2007.

Also, some other handy numbers to have are the serial #'s on the transmission bell housing:

The last 6 digits are as follows:

2002 - 4VN2AA

2003 - 4VN2BA

2004 - 4VV4AA
[end Up-Date]

So From this, I can say that the gears in the WRX from 2003 - 2007 are for all intents and purposes the same. One interesting re-design I did notice is the ring on 3rd that keeps the hub from sliding into the actual gear itself. I noticed this because on my 03, it is a metal ring that is welded to the synchro, and on my 3rd gear, that ring came lose, and was basically chewed up (which accounted for some metal in my transmission). On the later WRX gears, and on both the Legacy GT gears, and STI gears that I put in, this has been done away with, and incorporated into the synchro design.

So on to the pictures. First is a picture of the WRX gears compared to the Legacy GT gears, and second is a comparison with the STI V.6 Gears:

http://i62.photobucket.com/albums/h112/Scubynubie/WRXLGTComp2-MedLogos.jpg

http://i62.photobucket.com/albums/h112/Scubynubie/WRXSTIV6Comp1-MedLogo.jpg

It is somewhat apparent from the pictures, but more apparent in person that the LGT and STI V. 6 gears are thicker than the WRX gears.

But because it doesn't come through in the pictures as well as it could, I decided to take some measurements. Now, I will say that this proved to be much harder than I expected at first because of the shape of the gear teeth. I used a caliper, and tried as best as I could to measure at the base of the tooth above any curvature of the trough between the two teeth. But with that said, I am going to say that my measurements are acurate +/- .1mm, though I might be giving myself too much credit.

Here are the numbers that I got after measuring 3-4 teeth on each gear, and taking an average. It is also worth noting that the WRX gear have been run in a car, where the LGT and STI gears were brand new ,and the STI gears are also REM treated.

For the WRX Gears:

2nd - 5.35mm
3rd - 3.76mm

05 - 07 Legacy GT Gears:

2nd - 5.92mm
3rd - 4.41mm

STI V.6 Gears:

2nd - 5.92mm
3rd - 4.39mm

STI RA Gears:

2nd - 6.03mm
3rd - 5.28mm

So basically, I am going to assume that the Legacy GT gears and STI V.6 gears have the same tooth thickness which isn't surprising because they are the same ratios after all. And I'll say that the difference between 3rd gear teeth is just my measuring error.

Lastly, I have taken pictures of the RA gears compared to the WRX gears. The base width of the teeth is listed above, and these are the widest of the Subaru gear sets.

http://www.flatironstuning.com/images/RA%20Gearset%20Comparison%20Labeled-small.jpg

Also, for anyone interested, here are the ratios for the above sets:

JDM STI V.6
Legacy GT (2005 - 2008)
1st-3.166
2nd-1.882
3rd-1.296
4th-0.972
5th-0.738

JDM STI-RA
1st - 3.083
2nd - 2.062
3rd - 1.545
4th - 1.151
5th - 0.825

USDM WRX
1st - 3.454
2nd - 1.947
3rd - 1.366
4th - 0.972
5th - 0.738

Cooley

Bob_n_Cincy
04-03-2014, 06:03 PM
welcome Cooley
Do you know if there is a strength difference in a 5mT from a 06 NA impreza and a 06 WRX.
I know about the clutch difference.
I have a 06 NA 5mt I'm using on my 04 FXT engine. I'm wondering if it will break fast because it is weaker or last longer because it wasn't beat.
Thanks
Bob

longislandwrx
04-04-2014, 06:08 AM
where did it go?

FlatironsTuning
04-04-2014, 09:40 AM
welcome Cooley
Do you know if there is a strength difference in a 5mT from a 06 NA impreza and a 06 WRX.
I know about the clutch difference.
I have a 06 NA 5mt I'm using on my 04 FXT engine. I'm wondering if it will break fast because it is weaker or last longer because it wasn't beat.
Thanks
Bob

I have not seen anything definitive, but the NA transmissions do not seem to be as durable. Many people tend to have transmission issues after doing a swap into an NA car and that is why I say that. However, on paper, the shorter final drive, and ratios don't give any obvious reason for this.

I'd say that it would be worth running the transmission you have and hopefully it will hold up. As the 818 is much lighter than a Subaru, and depending on your power goals, it is definitely possible that the transmission will last for a while.

FlatironsTuning
04-04-2014, 09:41 AM
where did it go?

I don't know, but I'm sure it will be in the last place you look for it.

icky
04-04-2014, 10:40 AM
the 818 is much lighter than a Subaru, and depending on your power goals, it is definitely possible that the transmission will last for a while.


400 ft lb is the same regardless of car weight. Same reason they don't take car weight into consideration in clutch capacity.

Bob_n_Cincy
04-04-2014, 11:01 AM
I have not seen anything definitive, but the NA transmissions do not seem to be as durable. Many people tend to have transmission issues after doing a swap into an NA car and that is why I say that. However, on paper, the shorter final drive, and ratios don't give any obvious reason for this.

I'd say that it would be worth running the transmission you have and hopefully it will hold up. As the 818 is much lighter than a Subaru, and depending on your power goals, it is definitely possible that the transmission will last for a while.

Thanks Cooley
Maybe people that do a NA to Turbo swaps are also aggressive drivers.

Your "shorter final drive" comment got me thinking.
04 forester NA 4.11
04 Forester XT 4.44
06 inpreza NA 3.90
06 WRX 3.70
My 3.9 with 2nd gear gives me 27 to 55 MPH in the 3000-6000 power band. That should work pretty good for autocross.
Bob

Bob_n_Cincy
04-04-2014, 11:05 AM
400 ft lb is the same regardless of car weight. Same reason they don't take car weight into consideration in clutch capacity.

You can't get to flywheel 400 ft-lb on the 818 in 1st or 2nd because the tires will break loose :).
Third gear is another problem.
Bob

Scargo
04-04-2014, 12:48 PM
Thanks Cooley
Maybe people that do a NA to Turbo swaps are also aggressive drivers.

And people who turn their Subies into 818s are what kind of driver?:rolleyes:

What about ring and pinion options?

FlatironsTuning
04-04-2014, 01:33 PM
Thanks Cooley
Maybe people that do a NA to Turbo swaps are also aggressive drivers.

Your "shorter final drive" comment got me thinking.
04 forester NA 4.11
04 Forester XT 4.44
06 inpreza NA 3.90
06 WRX 3.70
My 3.9 with 2nd gear gives me 27 to 55 MPH in the 3000-6000 power band. That should work pretty good for autocross.
Bob

Bob, you are definitely thinking about the gearing in the correct way. If your final drive is too short, you may have to keep shifting between 2nd and 3rd, where as if you had a taller final drive, you could stay in second.

With the 818, you have the opportunity to really fine tune your ratios to get them where you want to be based on your target speeds for a track or autocross, etc.

Canadian818
04-04-2014, 01:58 PM
Is there any difference in strength between 6spd with or without dccd? They're a lot cheaper without.

FlatironsTuning
04-04-2014, 03:05 PM
Is there any difference in strength between 6spd with or without dccd? They're a lot cheaper without.
At least here in the states, the only 6MT that we got without a DCCD was the Legacy GT Spec-B. That trans is the same case as the STI 6MT, but it has a viscus center diff, and it has an open front diff as well. The Spec-B transmission is about the same cost as the 2007 STI trans that we typically sell, but again, it has an open front diff. For the 818, having that front TBD or LSD would be really important I would say.

I don't remember if there is a JDM STI 6MT that had a viscus center diff, so I'll have to check into that. Off the top of my head I don't think that there is though.

And if you are looking at the newer 6MT's that are coming out, say in the 2010 Legacy, or the new WRX for instance, those are based on the 5MT, not the STI 6MT.

C.Plavan
04-04-2014, 04:24 PM
You can't get to flywheel 400 ft-lb on the 818 in 1st or 2nd because the tires will break loose :).
Third gear is another problem.
Bob

That is exactly why I bought 2 Legacy GT transmissions :)