STi Transmission

[Louisromersh]

So I've seam to lost my bookmark to the thread about some one modding a 818S to accept
the STi 6 speed manual transmission, could you guy's help out and post a link to it that would be great.

Also has there been any updates from FFR on the ability to install the 6MT without having to do modifications to the frame?

Thanks
Louis

[bbjones121]

Not yet, but their red car had the 6spd

[Kurk818]

This?

http://thefactoryfiveforum.com/showt...-speed-tran-in

[Louisromersh]

Thanks Kurk818 that is what I was looking for.

[Louisromersh]

Kurk818 I got another question for you,

besides the transmission mounting what else is different when I try to use a STI donor? If you could point out the big problem parts that would be great.

Louis

[Goldwing]

If you could point out the big problem parts that would be great.

Louis

Why did I hear that in the boss from "Office Space's" voice, lol?

The 2WD conversion is different with an extra reverse lockout issue. FFR, while not supporting the STI donor, does have a few parts to sell and will likely support the 6-spd tranny in the future. The whole STI is less likely, but could happen. The front knuckles require a bracket mod, removing a spacer, whose existence hints at a possibility of STI support down the road. Driveshaft and hubs are different. I haven't paid enough attention to explain what solutions have been made to make that work. Some years might have a clearance issue at the turbo with the rear strut brace requiring another frame mod. That's what I have off the top of my head.

[Kurk818]

Why did I hear that in the boss from "Office Space's" voice, lol?

The 2WD conversion is different with an extra reverse lockout issue. FFR, while not supporting the STI donor, does have a few parts to sell and will likely support the 6-spd tranny in the future. The whole STI is less likely, but could happen. The front knuckles require a bracket mod, removing a spacer, whose existence hints at a possibility of STI support down the road. Driveshaft and hubs are different. I haven't paid enough attention to explain what solutions have been made to make that work. Some years might have a clearance issue at the turbo with the rear strut brace requiring another frame mod. That's what I have off the top of my head.

What he ^^^ said. I got around the axles by using the OEM ones. This does widen the wide of the car tho but since im using 295's, i was already planning on widening the body. STi axles add about 1" to 1-1/8" additional width.

Additionally, the electrical is another hurdle if you plan on slimming down the harness. I kept the ABS system which is complicated by the DCCD system (which was removed for the 2wd conversion).

I have just the shifter to mount and itll be a complete roller. All the electrical slimming is completed and engine purrs like a kitten.

Already a bigger turbo and injectors on the shelf ready to install

[Boog]

What he ^^^ said. I got around the axles by using the OEM ones. This does widen the wide of the car tho but since im using 295's, i was already planning on widening the body. STi axles add about 1" to 1-1/8" additional width.

So the 6spd front axles outer spline and diameter will mate with the rear CVs? or front outer CVs mate with rear 5x114.3 hubs? Or the rear axles inner spline and diameter will mate with the 6spd front inner CV? or the entire rear axle assembly fits into the front ports of the 6spd?

Above doesn't make all that much sense, i'm just trying to understand what combination pieces were used from where to get the final solution:
[Rear 5x14.3 Hub] -> [Front or Rear outer CV] -> [Front or rear axle shaft] -> [Front or rear inner CV] -> [6spd trans front drive]

[Drew P]

If you are looking for the closer gear ratios that you get with the 6 speed STi tranny, but dont want the extra hassles of dealing with it, drop a RA gearset in a 5 speed tranny. You get stronger gears, close to the same ratios, and you save about 75 pounds over the 6 speed.

[Hobby Racer]

If you are looking for the closer gear ratios that you get with the 6 speed STi tranny, but dont want the extra hassles of dealing with it, drop a RA gearset in a 5 speed tranny. You get stronger gears, close to the same ratios, and you save about 75 pounds over the 6 speed.

Who manufactures the RA gearset? Got a web address?

[Sgt.Gator]

Rallispec
http://www.rallispec.com/gea_syn_rst1140.html

[Scargo]

Wouldn't this Tomioka gearset work? At $620, about 1/3 the price...

[matteo92065]

Wouldn't this Tomioka gearset work? At $620, about 1/3 the price...

It looks like that's just the input shaft, you would still need the gears, right? Additional $2370 gear set

[Scargo]

That's right. I wasn't paying attention.
I am putting a six-speed in mine. Paid $2,200 for a 33K mile tranny that turned out to be in great shape and then I've put $500 into it for close-ratio fifth and sixth gears (JDM gears).

[sponaugle]

So the 6spd front axles outer spline and diameter will mate with the rear CVs? or front outer CVs mate with rear 5x114.3 hubs? Or the rear axles inner spline and diameter will mate with the 6spd front inner CV? or the entire rear axle assembly fits into the front ports of the 6spd?

Above doesn't make all that much sense, i'm just trying to understand what combination pieces were used from where to get the final solution:
[Rear 5x14.3 Hub] -> [Front or Rear outer CV] -> [Front or rear axle shaft] -> [Front or rear inner CV] -> [6spd trans front drive]

I am also using an STI as a donor car (build thread in sig). I am using the front axle shafts with the front Inner CVs and the rear outer CVs. You have to use the rear outer CVs with the rear hubs, but fortunately they fit onto the front axle shafts. Equally you have to use the front inner CVs as the rear inner CVs are designed for the rear diff which is a different design. I am actually using a built 5-speed that Andrewtech built and modified to take the regular front STI inner stubs.

In your diagram speak:

[Rear 5x14.3 Hub] -> [Rear outer CV] -> [Front axle shaft] -> [Front inner CV] -> [6spd trans front drive]

Make sense?

[Drew P]

There was another brand that made a good 5 speed gear set that I was looking at when I did my RA gears. I have been racking my brain trying to remember the name of the company. It hit me a couple of minutes ago. M Factory does a 5 speed, but they also do a bunch of custom stuff too. I don't know anyone that has used them, but when I did my RA gear set, I was looking into these. They offer straight cut and helical gear sets. If you want to go as far as choosing each gear ratio, you can, but they also have a set gear set for the WRX 5 speed tranny that you can get without having to figure all that out.

They were a little more pricey than the RA gears. The determining factor for me was price and that the M Factory 5th was just too short for daily driving and I spend a lot of time on the freeway. But it is another option for 5 speed gears. I don't remember if they made a 6 speed gear set or not.

[Sgt.Gator]

Drew P > I use the M Factory LSD in my Acura race car, and they also own Syncrotech transmissions who supplied me a rebuilt tranny with the M Factory LSD installed. I am impressed with the quality and customer service there. They are highly regarded in the Honda/Acura community. If M Factory would make a front helical LSD for the Subaru 5 speed I would use it in a heartbeat. I have no reason to think their Subaru 5 speed gearset would not be great quality too. http://www.teammfactory.com/close-ratio-gears

[Boog]

I am also using an STI as a donor car (build thread in sig). I am using the front axle shafts with the front Inner CVs and the rear outer CVs. You have to use the rear outer CVs with the rear hubs, but fortunately they fit onto the front axle shafts. Equally you have to use the front inner CVs as the rear inner CVs are designed for the rear diff which is a different design. I am actually using a built 5-speed that Andrewtech built and modified to take the regular front STI inner stubs.

In your diagram speak:

[Rear 5x14.3 Hub] -> [Rear outer CV] -> [Front axle shaft] -> [Front inner CV] -> [6spd trans front drive]

Make sense?

Thanks!
I've been trying to figure out the 5x114.3 hub to 5spd plan and its good to know for sure that the key is in the trans stub shafts (and fully adjustable lateral links).

[sponaugle]

Thanks!
I've been trying to figure out the 5x114.3 hub to 5spd plan and its good to know for sure that the key is in the trans stub shafts (and fully adjustable lateral links).

Correct, although there are two paths you could take:

(1) Do what I did and use the factory STI front shaft with the STI rear outer CV and STI front inner CV. To do this you need to have your 5-speed modified to be able to accept the stub input. I believe this in only possible if you replace the center diff with an LSD diff.

(2) You can have a custom axle made by the driveshaftshop guys that has the STI outer spline (to fit your rear outer STI CV) and the WRX front inner CV spline (to fit a pair of front inner CVs you buy).

In that second case you have the advantage that you can run any 5-speed, and you don't need to worry about pushing the wheels out because the axle shafts will be the perfect length.

Jeff

[Boog]

Correct, although there are two paths you could take:

(1) Do what I did and use the factory STI front shaft with the STI rear outer CV and STI front inner CV. To do this you need to have your 5-speed modified to be able to accept the stub input. I believe this in only possible if you replace the center diff with an LSD diff.

(2) You can have a custom axle made by the driveshaftshop guys that has the STI outer spline (to fit your rear outer STI CV) and the WRX front inner CV spline (to fit a pair of front inner CVs you buy).

In that second case you have the advantage that you can run any 5-speed, and you don't need to worry about pushing the wheels out because the axle shafts will be the perfect length.

Jeff

It looks like the part numbers are shared for the bearings and seals between an '06 5-speed and an '06 6-speed, so using a new diff like a Quaife QDH3Y with the the old ring an pinion should let the STI inner CVs plug in?
Sounds like a plan.

[Scargo]

Drew P > I use the M Factory LSD in my Acura race car, and they also own Syncrotech transmissions who supplied me a rebuilt tranny with the M Factory LSD installed. I am impressed with the quality and customer service there. They are highly regarded in the Honda/Acura community. If M Factory would make a front helical LSD for the Subaru 5 speed I would use it in a heartbeat. I have no reason to think their Subaru 5 speed gearset would not be great quality too. http://www.teammfactory.com/close-ratio-gears

I guess you do not think much of the STi's helical limited slips and the M Factory's would be better if you could get it? I am just going by what I've read and been told, in that, helical LSDs are not the optimal design for racing. That's just what I ditched in my STi. I was told I could gain 1-2 seconds a lap by how the plate type transferred power better. Mind you, I've never known I had an inferior product for racing... My racing coach, who has driven my car at different tracks, said they would help (as would a good, two-way racing shock).
As mentioned previously, I went with custom tuned OS Gikens. Tomorrow I will see how they work on a familiar track.

[Turn In Concepts]

I wouldn't touch M factory gear parts for these transmission. They were proven to be less strong than a factory set of gears some years ago.

The RA gearset is no different than the late 03 to 05 gearset on the standard 5MT trans. There are some differences in the ratios here and there, but the overall strength is no different. I would look for a 4.44:1 R&P for the front to run with a standard 5mt gearset. It will be quite awesome.

There are some easy axles swaps you can do with the 6MT trans. You can use any late 04+ wrx axle in the late 04+ 6MT trans. The inner splines are the same. You can also easily convert any subless 04+ 6MT trans to a stubbed trans by installing the proper seals and axle subs. That will allow you to use the pinned axles from the 02 to early 04 5MT.

Tony

[Jaime]

I would look for a 4.44:1 R&P for the front to run with a standard 5mt gearset. It will be quite awesome.

I've had a 4.444 R&P for sale at NASIOC for the past six months. Not a nibble. Maybe I should put it back in?

[Sgt.Gator]

I guess you do not think much of the STi's helical limited slips and the M Factory's would be better if you could get it? I am just going by what I've read and been told, in that, helical LSDs are not the optimal design for racing. That's just what I ditched in my STi. I was told I could gain 1-2 seconds a lap by how the plate type transferred power better. Mind you, I've never known I had an inferior product for racing... My racing coach, who has driven my car at different tracks, said they would help (as would a good, two-way racing shock).
As mentioned previously, I went with custom tuned OS Gikens. Tomorrow I will see how they work on a familiar track.

No, Drew P was asking about, and we were discussing, the 5 speed tranny, not the STI 6 speed. My point was that if I could put a MFactory helical in my 5 speed LGT tranny (which has no front LSD at all) I would. On my LGT I've run the stock VLSD and the plated 1.5 way Cusco in the rear diff. The plated/clutch type Cusco works much better. Does it work a lot better than a helical? I doubt it.

As for the STI 6 speed, I just acquired a JDM Forester STI 6 speed that comes with the AP Suretrac LSD. I'm pretty confidant that it will work fine for racing even though it's similar to a Helical/Torsen type LSD. Snail Performance has one of the fastest, and occasionally the fastest, Time Attack cars in America, and they still run AP Suretrac on their 2003 STI and 2006 WRX, front and rear. http://www.snailperformance.com/time-attack-team.html . So the claim that a plated/clutch type is 2 seconds a lap faster than a Helical/Torsen/Suretrac is not working for me.

The plated diffs need maintenance, the helical/torsen do not. In my LGT it's not a big deal to drop the rear diff and pull the Cusco 1.5 way. However it's a much bigger deal to drop the tranny and split open the case to maintain a plated front diff. For me the performance gain, if any, is negated by the extra work. If I ever replace the AP Suretrac in the front diff it will be with a Torsen/Helical type, not a clutch type. The AP Suretrac are known to wear out so it will probably happen.

The performance advantage of a plated/clutch over a helical/torsen is that even if one wheel is completely off the ground, the other wheel still gets torque. If no wheel leaves the ground I don't believe there is any difference at all except the following: You can also "tune" a clutch type to change the engagement pressure and also change the way it engages from 1.0 to 1.5 to 2.0 type. How many people are going to split open their 6 speed to tune the LSD a little bit so that it engages at different pressures? Maybe a few professional race teams, but not anybody I race against. The only time that will happen is every off season when they go into it to do maintenance on the clutch packs.

The entire subject of which LSD is best is one of those things that gets argued over infinitum in forums. It's almost as bad as which oil is best for your engine!

Here's a great FAQ on differentials which is a combination of Unabomber's post on NASIOC and some more info for Legacy owners. It's worth a read if you are thinking about which of the many types of LSDs to get. We are unique in that we are converting what would normally be best for a front LSD into the what normally would be best for a rear diff LSD, so there it gets complicated.

http://legacygt.com/forums/showthrea...rs-112536.html Posts 1 and 3 are excellent.

How did you like your new OS Gikens? They are well respected for quality. Is your front a 1.0 way or 1.5?

[Drew P]

I wouldn't touch M factory gear parts for these transmission. They were proven to be less strong than a factory set of gears some years ago.

Tony

I hadn't found anyone that had any experience with the M Factory gears when I was looking. That what a while ago though. Sounds like I made the right decision going with the RA gear set instead!

[Sgt.Gator]

I wouldn't touch M factory gear parts for these transmission. They were proven to be less strong than a factory set of gears some years ago.
Tony

Thanks, I didn't know that. They are well known for Honda/Acura but apparently they haven't transferred that to Subaru. Do you have a forum thread on NASIOC or somewhere you can point to?

It's funny, on the LGT forum there are entire threads dedicated to bashing the Subaru 5 speed gears for weakness! Particularly 5th gear is complained about for blowing up. Here's one of many:
http://legacygt.com/forums/showthrea...ad-222455.html

[Sgt.Gator]

I hadn't found anyone that had any experience with the M Factory gears when I was looking. That what a while ago though. Sounds like I made the right decision going with the RA gear set instead!

Here's one on NASIOC: My mFactory / DS1 5spd install diary: http://forums.nasioc.com/forums/show....php?t=1559347

[Scargo]

My point was that if I could put a MFactory helical in my 5 speed LGT tranny (which has no front LSD at all) I would. The plated/clutch type Cusco works much better. Does it work a lot better than a helical? I doubt it.

So the claim that a plated/clutch type is 2 seconds a lap faster than a Helical/Torsen/Suretrac is not working for me.

The plated diffs need maintenance, the helical/torsen do not. In my LGT it's not a big deal to drop the rear diff and pull the Cusco 1.5 way. However it's a much bigger deal to drop the tranny and split open the case to maintain a plated front diff. For me the performance gain, if any, is negated by the extra work. If I ever replace the AP Suretrac in the front diff it will be with a Torsen/Helical type, not a clutch type. The AP Suretrac are known to wear out so it will probably happen.

The performance advantage of a plated/clutch over a helical/torsen is that even if one wheel is completely off the ground, the other wheel still gets torque. If no wheel leaves the ground I don't believe there is any difference at all except the following: You can also "tune" a clutch type to change the engagement pressure and also change the way it engages from 1.0 to 1.5 to 2.0 type. How many people are going to split open their 6 speed to tune the LSD a little bit so that it engages at different pressures? Maybe a few professional race teams, but not anybody I race against. The only time that will happen is every off season when they go into it to do maintenance on the clutch packs.

How did you like your new OS Gikens? They are well respected for quality. Is your front a 1.0 way or 1.5?

I mean no disrespect and you may have more experience racing and working on race cars than I.
How can you say the Cusco works much better and then, immediately follow by saying you doubt it works a lot better than a Torsen/helical LSD?
You also say the benefits are there for a plate type LSD if you get a wheel off the ground. Having power to the ground vs not is going to make you faster. And, as you say, they can be tuned.* That makes them perform better. One or two seconds, depending on the track and its length, may or may not be a stretch. One reference to gaining time was made to a track I love, Watkins Glen, which is 3.4 miles long and around two minute laps for a fast car.
I did everything myself on my six-speed. To adjust the diff you do not split the case; just take the bellhousing end off. On an 818 this won't be that much of a chore and it won't be done time and time again; just till you get it where you want it and when it wears out.
About wearing out: OS Giken uses ribbed discs, not friction discs. These are supposed to wear very little.
* Mine are variants of 1.5. I would have to look at my notes or call the OS Giken tech to be positive, but on my STi I think the front leaned towards 1 and the rears toward 2. I'm fuzzy about this at the moment. They did take into account that I had 400 WHP on a dedicated track car at under 8:1 P/W. I will be trying them out for the first time tomorrow and will report back. When I did tight turnarounds they did not balk at all.

[ssssly]

I wouldn't touch M factory gear parts for these transmission. They were proven to be less strong than a factory set of gears some years ago.

The RA gearset is no different than the late 03 to 05 gearset on the standard 5MT trans. There are some differences in the ratios here and there, but the overall strength is no different. I would look for a 4.44:1 R&P for the front to run with a standard 5mt gearset. It will be quite awesome.

There are some easy axles swaps you can do with the 6MT trans. You can use any late 04+ wrx axle in the late 04+ 6MT trans. The inner splines are the same. You can also easily convert any subless 04+ 6MT trans to a stubbed trans by installing the proper seals and axle subs. That will allow you to use the pinned axles from the 02 to early 04 5MT.

Tony

The VII-IV, excluding the 22B and v-limited trannies , are roughly the same as the US 5 sp.

The V5/6 VB1EA RA tranny (also used in the s201) is not. It has a helical front diff, with thicker, treated gears. And I would rate them as anecdotally stronger than standard USDM 5 speeds.

I have never scientifically tested them, but they are more massive than other 5 speed trannies. Having shipped many of them from Japan, they are about 20% more to ship (hence I assume heavier). And having spent 7 years in Japan racing against them regularly, I only saw one of them blow on the track, VS one every week or two for non-VB1EA 5 spd trannies.

So could it have been the drivers and a shipping cost variation anomaly? Yes. But being as they are different part numbers from the same gears used in similar trannies and if you put them next to the gears out of another 5 speed they are visibly thicker, combined with my other personal observations, I'm going to say they are more than likely stronger.

I would love to see an actual stress test comparison though. Maybe we should start a kiskstarter to raise $100k for gears and test equipment.

[Sgt.Gator]

I mean no disrespect and you may have more experience racing and working on race cars than I.
How can you say the Cusco works much better and then, immediately follow by saying you doubt it works a lot better than a Torsen/helical LSD?
You also say the benefits are there for a plate type LSD if you get a wheel off the ground. Having power to the ground vs not is going to make you faster. And, as you say, they can be tuned.* That makes them perform better. One or two seconds, depending on the track and its length, may or may not be a stretch. One reference to gaining time was made to a track I love, Watkins Glen, which is 3.4 miles long and around two minute laps for a fast car.
I did everything myself on my six-speed. To adjust the diff you do not split the case; just take the bellhousing end off. On an 818 this won't be that much of a chore and it won't be done time and time again; just till you get it where you want it and when it wears out.
About wearing out: OS Giken uses ribbed discs, not friction discs. These are supposed to wear very little.
* Mine are variants of 1.5. I would have to look at my notes or call the OS Giken tech to be positive, but on my STi I think the front leaned towards 1 and the rears toward 2. I'm fuzzy about this at the moment. They did take into account that I had 400 WHP on a dedicated track car at under 8:1 P/W. I will be trying them out for the first time tomorrow and will report back. When I did tight turnarounds they did not balk at all.

Scargo I guess I wasn't clear on what I meant: "On my LGT I've run the stock VLSD and the plated 1.5 way Cusco in the rear diff. The plated/clutch type Cusco works much better." To clarify, an LGT comes stock with a Viscous Limited Slip Diff, VLSD. The VLSD is not a good LSD for anything, much less racing. The Cusco plated rear diff works much better than the the stock VLSD. I doubt it works much better than a Torsen/Helical/SureTrac. Does that make more sense now?

On adjusting the diff you said "I did everything myself on my six-speed. To adjust the diff you do not split the case; just take the bellhousing end off. On an 818 this won't be that much of a chore and it won't be done time and time again; just till you get it where you want it and when it wears out." How do you adjust the front diff without taking it out of the trans case? Do the OS Giken diffs have a way to do that? For the Cusco and other plated I am familiar with you have to remove them from the tranny. From reading the transmission manual and and forum posts it looks like getting to it is very involved and requires special tools and skill, something I would not attempt. Did you install your OS Giken front diff too? Congrats, I am not that brave.

And when I say split the case, that's a term left over from many 5 speed discussions. For the 6 speed I mean taking it apart and pulling out the guts when I say that.

Although this does not apply to our 818 projects, but for sake of general Subaru discussion, the center diff is easy to get to when you take the extension case off.On your USDM STI it has a DCCD controlled Center diff, which means it's a clutch type electronically controlled. On older JDM STI 6 speeds, all Legacy Spec B 6 speeds, and all Turbo 5 speeds, it's a VLSD. My JDM Forester STI 6 speed has a VLSD, so a future upgrade may be to swap in a DCCD unit, a Cusco clutch LSD, or find a Torsen type center diff. I'm not aware of any Torsen center diffs for the 6 speed. PPG makes a Torsen Center diff for the 5 speed,, but it's very expensive, like all PPG stuff. .

When the AP Suretrac front diff wears out I will probably swap it for a Quaife QDH3Y (Torsen Type), which also is the one a lot of folks here are using in their 5 speeds. It fits both.

And like I said earlier, it becomes an endless argument about Clutch/Plated/Torsen/Helical/Suretrac. The only thing there seems to be agreement on is that if you are going to race to dump the Viscous LSDs.

For anyone here not familiar with what 1.0 / 1.5/ 2.0 way LSDs means, this Cusco guide is pretty good at explaining it and what types of racing would use each kind:
http://www.cusco.co.jp/en/pdf/LSD%20Guide%20Final.pdf

And no, I am not vastly experienced at racing or on Subarus. I've been wheel to wheel racing 3 years in an Acura Integra, I don't count AutoX or HPDE as racing in the context of this discussion as they don't stress a car anything like wheel to wheel, but I do have a lot of years at that. I won my first AutoX in 1973 with the Georgia Tech Sports Car Club. I forced immersion on myself into Subarus so I could learn about them before building an 818R. My forced immersion was buying the LGT race car, and I've only owned it a year. So this is all my humble opinion and YMMV. Take anything I say with a grain of salt, my only defense is that I've done a lot of research on Subaru transmissions and differentials, but I lack practical knowledge as to actually tearing one apart and rebuilding it. If you tore yours apart and installed a front LSD diff, you are WAY ahead of me.