There are many differences between the 5-speed we get in North America as OEM and the 6-speed WRX transmissions that come on New Age STi’s in Japan, Europe and Australia. First of all, the 6MT is approximately 85lbs heavier than the 5MT. The added weight comes from stronger and larger gears, various hardware, internal oil pump and generally larger size. The teeth profile has been altered to improve the gear mesh and reduce gear whine. Shifting mechanism was also reworked to increase the shifting response and reduce the possibility of gear clash. “Short shifting” already occurs inside the transmission case and nearly eliminates the need for a shirt shift kit. Subaru also increased the performance of the synchronizer by installing two linear ball bearings on each of the five shift rails. The new double-cone cone synchros on 1st and 2nd and triple-cone synchro on 3rd gear also add up to the over all strength and smoothness of the 6MT transmission. Last but not least, gears and some other parts of the 6MT has been carburized and quenched as well as shot peened. These processed insure the maximum strength of the metal. Another important bit about the internal differences is the fact, that the center diff / final drive gear are enclosed and have its own oil passages, keeping the potential metal bits from the gears away from it. Finally, the clutch slave cylinder has also been reworked to improve the pedal feel and ensure its maximum performance during the most demanding conditions.

One of the main great advantages of the 6MT transmission, is that it allows the driver to use the engine’s power more efficiently and insure that there is enough “oomphhh” in every gear at any speed. That is where the gear ratios come into the game.

The 2 bottom tables show the gear ratios of 6MT and 5MT. 6MT’s in UK and Europe are available with taller 5th and 6th gears. They are shown in bold.

The JDM 6MT will turn about 400RPM faster in 6th gear at around 60MPH.

JDM/European 6MT Gear Ratios

1st Gear 3.636
2nd Gear 2.375
3rd Gear 1.761
4th Gear 1.346
5th Gear 1.062 / 0.971
6th Gear 0.842 / 0.756
Reverse Gear 3.545
Final Gear 3.9

US 5MT Gear Ratios

1st Gear 3.454
2nd Gear 1.947
3rd Gear 1.366
4th Gear 0.972
5th Gear 0.738
Reverse Gear 3.333
Final Gear 3.9


Regular 6-speed gearboxes offer a 50/50 front/rear torque split. However, some STi WRXs are also available with the optional digitally controlled center differential or simply DCCD. Normally, the DCCD is set at 38/62 split and can be set towards 50/50 and locked position.

The above were the most important differences between the 6-speed and 5-speed Subaru transmissions.

Now, let us take a look at some pictures and analyze the external structural changes.

http://www.i-club.com/images/articles/6mt_front.jpg

Here are both transmissions side-by-side. As you can probably tell, the one on the right is much “beefier”. Not only it is longer, but also wider and more resembles a rectangle rather than a triangle. You can also see massive ridges that are cast into the case. They provide additional case rigidity and could also possibly improve cooling of the gearbox. Both transmissions consist of three main parts, the gear/bell housing, the center diff housing and the final drive housing. As you can tell, each of them on the 6MT is much bigger. The front/bell housing keeps the front SureTrack LSD nice and comfy with plenty of room and fluid. The front diff is kept separate from the gears and has its own oil galleries as I mentioned earlier. The bearings inside are also larger and stronger, according to my source. The middle, center diff housing is also separated from the rest of the transmission. Big bearings, large oil galleries and tranny fluid pump are all here. Finally, the rear housing is where the final drive gear resides.

http://www.i-club.com/images/articles/6mt_rear.jpg

This is a nice close up shoot from the rear of the transmissions. I know I said it many times already, but everything is “big” on the 6MT comparing to the fragile 5MT. Plenty of those ridges talked about already.

http://www.i-club.com/images/articles/6mt_right.jpg

I personally think that the iron cast girdle that you can see in this picture is one of the most important structural improvements. Also notice the oil pump line that goes from the center section to the front one. That’s one of those special oil passages we talked about.

http://www.i-club.com/images/articles/6mt_left.jpg
Girdle-girdle! I am pretty sure some of those plugs can be removed and used to hook up a tranny oil cooler. Also notice the dipstick.

If you aren’t convinced yet that 6MT is THE transmission of your dreams, please stay tuned for the next article, where I will talk about the rear diff, driveshaft, axles, hubs and shifter.

hey alex

great info

will this tranny fit in the older chassis? the gc8 or the wagon?

just curious of course :)

josh

wow, I had never seen 6MT and 5MT side by side.
6MT looks a lot rigid.
this one doesn't have DCCD right?

Josh,

AFAIK, the tranny will fit the GC. However, being wider, you might have to hammer the body a bit to make it clear. I am not sure about it. I need to dig up some of my old GC pics and I will be able to tell.

Yohei,

No, this is the regular 50/50 one. The DCCD has wires all over the place AFAIK.

I was trying to find some info on the SureTrack LSD's and couldn't find any. All I know that STi WRX's have SureTrack's in both front and rear. Both of them are LSD's. And, SureTrack is made by AP. If anyone know more about them, please let me know.

I think the front diff is open for the non-DCCD STI tranny.
I'll double check.

Ok, I looked the broschure
TypeRA with DCCD ....F/suretrac R/clutch
TypeRA with Brembo (no DCCD) F/suretrac R/suretrac
STi .....F/optional suretrac R/suretrac

so your 6MT may or may not have suretrac in it.

Suretrac was trademark of AP but AP is absorbed by Delphi now :(

all right,
I found info on Suretrac, if Suretrac related stuff needs to move to another thread, please do so.

Suretrac was jointly developed by Automotive Products (AP) and Fuji Univance. Somehow AP has the trademark.

I found this press release of Fuji Univance
read this
http://www.uvc.co.jp/news_release/00-10-26_e.htm

and then here is how it works...although I still don't understand...
http://www.uvc.co.jp/products/coupling/axc/axc_cld_e.htm

I think what it does is..
less torque = more like open diff
greater torque = becomes more like LSD
and the slip is proportional to the torque input.
So..when cornering or under brake, it's open diff so that you can turn in well, but while you are on the gas, it's LSD for stability.

Suretrac is not very strong so if want more LSD, I suggest you to change it to clutch type. Cusco LSD typeMZ

Here is some terrific info to read about the six speeds suretrack LSD. There is also excellent info about all of the sti's major components, engine, trans, diff's, suspennsion ect ect., enjoy... Maybe this info should be made into a sticky ??
http://subaru.com.au/downloads/63748.pdf
Tom
P.S. I can't wait until my sti motor and trans gets here..

oops, he, he..
Tom

FANTASTIC!

Thank you for this artile and all the work that went into it. This sort of information is like gold. One request, please include citations for the sources of information. So readers can dig around too. I am new to subarus and don't know where to look for primary sources, stuff like this.

Two questions: Will one of these fit in the 2002 USA cars? (see how unfamiliar I am with these things?)

Will a Torsen differential fit? If not in Transmission in front and / or rear?


Again, this is great stuff.

Alex's, and my 6MT are both "sure-track" front diffs. How do I know you ask? We both bought them from the same dude.

There are not too many non sure-track trannies out there.

Here is what I found out:

Part numbers for the 6MT trannies:

32000AF460 Standard
32000AF500 w/ SureTrac
32000AF470 w/ DCCD and SureTrack

My tranny is the one with SureTrack. ;)

- Alex

P.S. Thanks Jude.

Jude is the man!

great info guys.

i would be very interested to see how it ifits in a GC.

thanks for all the info guys. great stuff

josh

this is just the kind of info we need, and the involvement that was missing from the old iclub :D

Awesome series, Alex!

It does, one of my Mechanic friends has attached the 6 speed to his version 3 motor on his 99 RS.

Don't think he had to hammer anything out though, but I'll ask.

hey, liek how come u only have the 6MT with SureTrack and not the SureTrack and DCCD? is it harder to install or sumthing? and if i wanted the one with SureTrack and DCCD, where would i go about finding one?

jaimak

that is great news. i have been contemplating a GC project and wanted to do a ej20 and 6sp swap. i am thinking about a killer GF8 project. i just dig the older chassis.

that is great you guys got the suretrac. i need to go read up on what it is.

josh

I spoke with BOZZ Speed of Japan tuners was told that the DCCD tranny is not that good for my needs. My car will put out double if not more the STi power and those DCCD's are not as strong as the regular diffs.

- Alex

I read somewhere once that one of the reasons that the US sees more 5MT are because by adding a 6th gear, most cars will need to be in 3rd to reach 60. With this additional shift comes a slower 0-60 time, which Americans are enamored with, especially in the sport compact market. May be why the new Neon is only a 5MT too. Makes sense too because most drivers in the don't really understand why a 6MT is necessary for driving anyway.

Hey guys, whats up. The 60/30 somthing Tq split, how much more does that cost. That is something thats very very important to me. I was hoping for more like a 25/75 split. Any prices??

Thanks a ton.

Noah

The DCCD equipped 6MT's are expensive. Expect to pay about ~$4,500-$5,500 for just a used DCCD tranny. Then you need the dash cluster, the DCCD ECU, harness and the knob.

You can have a 65R/35F perm bias if you get a CUSCO Tarmac Gear center diff.

- Alex

FYI: Cusco taramac gear is an open diff so make sure you have Front and Rear LSD as well.
I've been thinking about putting this setup for a long time.

No problem Josh.

The friend I speak of used to run an STI RA gearbox which was waaay to short (and fragile) for his everyday use, and in went the 6 speed. Like I said, he didn't mention having any problems, but there are others that have done it, like Bill Shih's GF8 (In the Nasioc members gallery, if you want project inspiration, that's it.)

hey jai



what state is he in?

i dont think you can search on peoples names

josh

sweeet. How much would the whole setup cost aprox.?$5k is out of my price range for right now, but if i could just get the diff. that would be sweet. What front LSD would you guy recomend?

Thanks a ton.

Noah

You'll loose ABS with the DCCD. They don't work together well.

dont like abs anyway. Im more interested in the tarmac diff, from cusco. anyone know how to get info on it and whatnot. thanks. noah

do a search on NASIOC there was a thread about it a while back.

It's an open diff so you should have LSD at both ends before using it. Not sure if it's for both 5 and 6MT or just the 6...

You'll loose ABS with the DCCD. They don't work together well.


Not true. It will work fine together. It is just not offered like that from the factory AFAIK. There are conversions in Japan that retain ABS and have DCCD.


It's an open diff so you should have LSD at both ends before using it. Not sure if it's for both 5 and 6MT or just the 6...


Your stock center diff is also open, no?

stock center diff is viscous LSD on pretty much any Subaru except DCCD model.

I knew that, of course. ;)

Great info on the new Trani!
Where did you guys order one of these from? And how much?

so in some ones post i thought that i read that the Uk and EU 6 speeds had the 1 to 1.1 center and a 3.51 to 1 rear diff .. any truth to that?

Yeah, are there versions of the 6 speed that use different differentials?:)

1. Do some 6 speeds come with 3.9, 4.111, or 4.444 front differentials?
2. Do some 6 speeds come with 1:1 or 1:1.1 ratios that allow the rear differential to be that same as or different than the front?

As mwizard asked previously, how much did this bad boy set you back Alex? That is if you don't mind sharing, of course. (If you don't tell, I'll have to find out from Andy :D)

I will discuss the costs in the upcoming articles. ;)

No, AFAIK, all 6MT's have 3.9 rear ends and 1:1 rear/front.

There is STi option part, that can change the 3.9 to 4.444. That will be too short if you ask me, but super cool for auto-x.

Originally posted by Imprezer
I will discuss the costs in the upcoming articles. ;)

No, AFAIK, all 6MT's have 3.9 rear ends and 1:1 rear/front.

There is STi option part, that can change the 3.9 to 4.444. That will be too short if you ask me, but super cool for auto-x.

You mean gymkhana. ;)

FOr those of you with questions on the DCCD here is what I have learned, first there is a different tranny case (or at least one half is different) you will need the control wheel, loom, ecu, and micro switch (for the handbrake). FOr the rally team they usually run a rear bias only locking the diff when they break a drive shaft in order to get more power to the front. THe center diff operates on resistor variance. Other than that you already know everything hope this helps a little.

Just some extra info on this set up - - I have run the stock 6 spd clutch and tranny now - VERY abusively - including at least 30 full out drag runs - with between 450 - 500 wheel HP on NOS and the whole set up is stil in one piece and runs as my daily driver - - on launch like that with the 5 spd would have melted a stock clutch

also - the suretrack diff is GREAT in the snow - like a jeep

over all the 6 spd id worth every penny

But the gears are NOT ideal for drag racing - and - You'll feel the extra 85 lbs - - (not to mention the extra weight in the rear diff and half shafts)!

6 spd rules

Will the US 6 speed be a new version?
Will it have different gear ratios to match the larger engine?
What are the front and rear diff ratios?

Can the US 6 speed be retrofitted into older Subes?

Originally posted by Alfriedesq
Just some extra info on this set up - - I have run the stock 6 spd clutch and tranny now - VERY abusively - including at least 30 full out drag runs - with between 450 - 500 wheel HP on NOS and the whole set up is stil in one piece and runs as my daily driver - - on launch like that with the 5 spd would have melted a stock clutch

also - the suretrack diff is GREAT in the snow - like a jeep

over all the 6 spd id worth every penny

But the gears are NOT ideal for drag racing - and - You'll feel the extra 85 lbs - - (not to mention the extra weight in the rear diff and half shafts)!

6 spd rules

Hey Al, when are you going to get the 2.5 block?

I ordered my sti today - hope it gets heer soon !

How much you want for the old car?:)

I am going to seel some stuff out of it - the 6 spd parts are available if anyone is intererested

How much are you letting the 6MT go for? And how harshly has it been treated? All race use? Thanks Al.

Prob $4,500.00 for the trans - clutch - shifter - F & R half shafts - driveshaft - rear diff - rear half shafts rear brembo breaks etc - - I'd sell it at this price but would want your 5 spd equivalent parts as a core !Its been raced two times - but baby shifted all the time and has only 5 k miles - most of it on real low boost

*has DCCD and ABS with EBD (electronic brakeforce distribution)
*has drive-by-wire throttlebody
*not know to currently have traction control or yaw control...but many parts seem to be in place
*has manual button and thumbwheel
*has temp sensor in R180 differential, diff temp warning light in gauge cluster
*has torque bias lights in gauge cluster
*3.9 front diff (not entirely sure)

Originally posted by Alfriedesq
Prob $4,500.00 for the trans - clutch - shifter - F & R half shafts - driveshaft - rear diff - rear half shafts rear brembo breaks etc - - I'd sell it at this price but would want your 5 spd equivalent parts as a core !Its been raced two times - but baby shifted all the time and has only 5 k miles - most of it on real low boost

Alfriedesq,
How long would you allow to get 5 sp back to you? Would you include shipping to me?
Mark

PM me your phone and we can talk about it - where abouts do you you live ?

First you say....

Originally posted by Alfriedesq
I have run the stock 6 spd clutch and tranny now - VERY abusively - including at least 30 full out drag runs - with between 450 - 500 wheel HP on NOS and the whole set up is stil in one piece and runs as my daily driver - - on launch like that with the 5 spd would have melted a stock clutch



Then you say....

Originally posted by Alfriedesq
Its been raced two times - but baby shifted all the time and has only 5 k miles - most of it on real low boost

Originally posted by Kaos22B
First you say....




Then you say....
The 6 spd clutch held together fine - and still drives every day and

i still think that the 5 speed unit would have blown up in one day

- but - I feel that one bad shift could grenade the 6 spd also - - in WRX's I think you have to shift very smoothly when you are over 450 wheel hp or the tranmission is going to have a very short life - period

in any event - i've had a lot of luck with the 6 sopd set up and with the 5 speed I had nothing but misery and breakdowns - are you trying to imply that the 6 speed is weak or that I'm falsly promting its strength ? All I can say is that my car won the shootout - and I've been driving it ver day since and so far it runs perfect and nothing has broke

Originally posted by Alfriedesq
The 6 spd clutch held together fine - and still drives every day and

i still think that the 5 speed unit would have blown up in one day

- but - I feel that one bad shift could grenade the 6 spd also - - in WRX's I think you have to shift very smoothly when you are over 450 wheel hp or the tranmission is going to have a very short life - period

in any event - i've had a lot of luck with the 6 sopd set up and with the 5 speed I had nothing but misery and breakdowns - are you trying to imply that the 6 speed is weak or that I'm falsly promting its strength ? All I can say is that my car won the shootout - and I've been driving it ver day since and so far it runs perfect and nothing has broke

No Al, Im saying you lied about how you drove on it, first you state that it was raced AtLEAST 30x, and then you say you only raced it 2x, babied it elsewhere. We know you raced that tranny so it helps to be upfront and honest when trying to sell it, otherwise we dont know what to believe when you speak. I say this because I was looking for a 6speed.

When I say 30 X - I mean 30 x 1/4 mile passes on the 6 spd - NOT 30 differnt trips to the track !

The tranny is already sold

But thanks anyway for the tenth degree interogation

Uh, 30 passes IS 30 races.

Originally posted by Alfriedesq
When I say 30 X - I mean 30 x 1/4 mile passes on the 6 spd - NOT 30 differnt trips to the track !


You ought to be a lawyer.:)

Originally posted by aspera
You ought to be a lawyer.:)

how do you think he makes all that money to sink into his car?!?! :D

When I say "You ought to be a lawyer", I mean that you *are* a lawyer, and a lawyer is what you should be...NOT "go be a lawyer, you'd be good at it"!:)

Yeah, that's the ticket.

Well all i canm say is - BUY yourself a 6 speed - they are amazing - AND - i cant wait till june to get my new 6 spd !

I can't wait until you get a new one either. I'd like to read your impression of the differences between your old and new cars. Enjoy it.

Did you guys use the WRX shift boot, or do you need the Sti one?

Putting in the six speed this weekend

I picked up two 6MTs this last weekend, and they actually differ slightly. They differ in the oil lines that run external to the case, I guess to the center/front diffs? One has a solid line from front to rear like the one in Alex's picture. The other one is different. It has two seperate lines that I'm presuming are for use with an external oil cooler for the transmission. The place I bought them wasn't sure what it came out of with that setup or whether it was an older or newer design. This is a picture of the setup.

http://www.kr4d.com/~phil/6spds.jpg

I guess one of the options on the sti-ra is for an external tranny oil cooler. I'll probably just route the line into itself for the time being until I can get the cooler and associated lines to use. If anyone has any info on the cooler used on the actual STi it would be greatly appreciated.

Loved the write up....
I'm doing some research on the "ID" of various models of 6MT. Thus far, these are the facts I've compiled. If anyone would like to add or edit, feel free to do so.

The 6MT id is located on the driver's side on a white tag. The id's first 6 digits should be:

TY856W

The following digits are the ones I'm trying my best to decipher. Here is what I've found with the last four digits of the 6MT id as it pertains to the diffs in the tranny:

TY856WB1AA is a STD frt, STD ctr 6MT, rev1
TY856WB1BA is a Suretrack frt, DCCD ctr, rev1
TY856WB1CA is a Suretrack frt, STD ctr, rev1
TY856WB2CA is an Export model (NZ, AU) 1.1:1 ctr?
TY856WB2FA is an Export model (NZ,AU), rev2
TY856WB2GA is a RA spec C w/DCCD,tranny cooler, rev2
I'm not sure on the 1.1:1 ctr diff model, but I'd really like to know. The revisions on the "rev2" model I believe had to do with the oiling system within the tranny. HTH

Steve

I have a "GA" trans in my garage. It does not have DCCD, but it does have the cooler lines.

dwx thanks for posting the picture of your tranny. I also have a six speed tranny sitting in my garage and it has the same tranny cooler inlet and outlet fluid lines as does yours. I would like to utilize a tranny cooler if possible so if you come across a source to get one please let me know.
Thanks, Tom..
Originally posted by dwx
I picked up two 6MTs this last weekend, and they actually differ slightly. They differ in the oil lines that run external to the case, I guess to the center/front diffs? One has a solid line from front to rear like the one in Alex's picture. The other one is different. It has two seperate lines that I'm presuming are for use with an external oil cooler for the transmission. The place I bought them wasn't sure what it came out of with that setup or whether it was an older or newer design. This is a picture of the setup.

http://www.kr4d.com/~phil/6spds.jpg

n2xlr8n I would like to thank you also, you just made my day.
I was told by the person whom I bought my sti six speed from that it had the front suretrack LSD diff option but at the time I couldn't find a source to verify the part numbers. But now I know per your reference ( B1CA ) that I do indeed have the front suretrack option, hooray...
Thanks again for the very helpful post.
Tom..
Originally posted by n2xlr8n
Loved the write up....
I'm doing some research on the "ID" of various models of 6MT. Thus far, these are the facts I've compiled. If anyone would like to add or edit, feel free to do so.

The 6MT id is located on the driver's side on a white tag. The id's first 6 digits should be:

TY856W

The following digits are the ones I'm trying my best to decipher. Here is what I've found with the last four digits of the 6MT id as it pertains to the diffs in the tranny:

TY856WB1AA is a STD frt, STD ctr 6MT, rev1
TY856WB1BA is a Suretrack frt, DCCD ctr, rev1
TY856WB1CA is a Suretrack frt, STD ctr, rev1
TY856WB2CA is an Export model (NZ, AU) 1.1:1 ctr?
TY856WB2FA is an Export model (NZ,AU), rev2
TY856WB2GA is a RA spec C w/DCCD,tranny cooler, rev2
I'm not sure on the 1.1:1 ctr diff model, but I'd really like to know. The revisions on the "rev2" model I believe had to do with the oiling system within the tranny. HTH

Steve

Originally posted by Sloppy Joe
n2xlr8n I would like to thank you also, you just made my day.
I was told by the person whom I bought my sti six speed from that it had the front suretrack LSD diff option but at the time I couldn't find a source to verify the part numbers. But now I know per your reference ( B1CA ) that I do indeed have the front suretrack option, hooray...
Thanks again for the very helpful post.
Tom..

That scenario is exactly why I started doing the research; my experience was opposite yours....glad I didn't buy it. Also glad I could help.

Cheers folks,

I totally forgot about posting what's necessary to fit the 6MT into a GC.

Again, like I said, it does. all that's necessary is that you use the Tranny mounts from a new age STI and it fits without having to modify the tunnel.

Hope that small tidbit o' info helps,

James

So...please let me in on where u bought these trannies from. My 5MT has broke twice now and I can't find the 6MT. With what I spent on those 2 i could of already had one!!!

Originally posted by axxis1
So...please let me in on where u bought these trannies from. My 5MT has broke twice now and I can't find the 6MT. With what I spent on those 2 i could of already had one!!!
Well an sti six speed will likely cost more than two WRX tranny's. I paid $4500 for my 6 spd ( includes clutch / flywheel / shifter and linkage and rear drive shaft ). Plus another $1500 for the H.D. r180 rear diff / hubs and axles ( which is optional and not necessary for the tranny swap ).
Tom.

P.S. some good advice would be to write down the tranny code numbers provided by n2xlr8n in this thread. This way you can cross reference and be sure your getting what you want. I was lucky in that the person I delt with was very honest.

is there any clearence problems of the transmission being larger , fitting in the tunnel of the car just curios

you can already order the usdm sti??

Originally posted by downshift
you can already order the usdm sti??

Yes, if you really want to go through the dealer telling you it'll cost $40,000 and trying to get them to sell it for MSRP.

well it dont matter.. im getting my sti in 2005 :D

Excellent article and responses.

Thanks all,
-Jon

are u selling a complete wrx 6spd conversion? what is your asking prices?