Please reconsider STi 6 Speed

[MurrayT]

Dave, Jim

I am pleased to read that I may use the 300HP engine from the donor 2006 WRX STi I purchased last week. I am disappointed that I cannot use the 6 Speed transmission.

From what I read the WRX 5 Speed cannot handle high horsepower and abuse. Many claim the STi's 6 Speed can handle over 500HP and considerable abuse. I am building this as a track car not a daily driver so high horsepower and abuse must be handled by a rugged transmission.

It seems the 6 Speed is the logical choice. Does FFR have a source on hardened 5 Speeds? I would prefer FFR give builders a choice between 5 or 6 Speeds.

Thanks for your time

[BrandonDrums]

It's been pretty heavily shelled out that the 5mt was probably going to be the only logical choice. The 5mt holds up fine to high-horsepower unless abused. Shedding 1500 lbs and making it 2wd will elminate many of the stresses that the 5mt has trouble tolerating during hard-launches (hard meaning side-stepping the clutch at 5k+ rpm)

The STI transmission has a MUCH more complicated center diff than the 5mt which can't easily be welded or replaced to make the tranny 2wd. Not only that, but it has far-shorter gearing that in a 1800-2k lb car will just limit the car's performance. It takes 3 shifts to get to 60 and with the shorter ratios in a lighter turbo car, the engine won't get enough load even in 3rd gear to see full spool. The 5mt is by far the only logical choice and given the size difference it's not surprising the kit won't have room for it.

That being said, there's a good bajillion guys out there who will swap their 5mt for your 6 speed at significant negative cost to you. I might be one of those guys if I don't build this kit.

http://thefactoryfiveforum.com/showt...ver-all-choice
http://thefactoryfiveforum.com/showt...useable-models.
http://thefactoryfiveforum.com/showt...p?78-Which-WRX

[keys2heaven]

It's been pretty heavily shelled out that the 5mt was probably going to be the only logical choice. The 5mt holds up fine to high-horsepower unless abused. Shedding 1500 lbs and making it 2wd will elminate many of the stresses that the 5mt has trouble tolerating during hard-launches (hard meaning side-stepping the clutch at 5k+ rpm)

The STI transmission has a MUCH more complicated center diff than the 5mt which can't easily be welded or replaced to make the tranny 2wd. Not only that, but it has far-shorter gearing that in a 1800-2k lb car will just limit the car's performance. It takes 3 shifts to get to 60 and with the shorter ratios in a lighter turbo car, the engine won't get enough load even in 3rd gear to see full spool. The 5mt is by far the only logical choice and given the size difference it's not surprising the kit won't have room for it.

That being said, there's a good bajillion guys out there who will swap their 5mt for your 6 speed at significant negative cost to you. I might be one of those guys if I don't build this kit.

http://thefactoryfiveforum.com/showt...ver-all-choice
http://thefactoryfiveforum.com/showt...useable-models.
http://thefactoryfiveforum.com/showt...p?78-Which-WRX

Brandon,

Do you know if you can mate an EJ257 block to a 5MT?

[Evan78]

Brandon,

Do you know if you can mate an EJ257 block to a 5MT?

Yes, you can. It happens all the time.

[MurrayT]

Brandon

Thanks for the explanation. It makes perfect sense.

If I am going to replace the 6 Speed with a 5 Speed I would like to get one that has been rebuilt to handle more power and heavy abuse. Know of anyone that specializes in building heavy duty WRX 5 Speeds?

I still would like to know about 5 Speed trans rebuilders that may add strength and dependability to the 5 Speed. Know of any?

[BoxerFanatic]

Brandon,

Do you know if you can mate an EJ257 block to a 5MT?

The EJ series engines ALL have the same bell housing pattern, as well as the EG, and EZ, and probably some of the new FB engines.

The WRX, Previous Legacy GT, and previous Forester XT both use the EJ25, with the 5-speed manual gearbox. The third digit of the engine code designates a calibration set. EJ255 was Legacy GT 245hp configuration, EJ257 is 305hp STI configuration. The turbo, intercooler, and Intake manifold are the big differences. The only internal difference might be sodium-filled exhaust valves in the 257.


BTW... the 2010+ Legacy GT's 6MT gearbox, what is likely to be more widespread with the next Impreza generation, is not the STI gearbox, but expanded from the 5MT gearbox, with the same bell housing, and it is ALREADY configured for cable-shift linkage, rather than solid linkage like most previous manual Subarus. Cable shifting, as well as being the same symmetrical-AWD system as the 5MT, make it almost a ready-made solution for this car.

The only thing that needs to be done is to convert it to 2WD only. There is a company that does that, Bremar Automotion, mostly for VW conversions to Subaru engines and gearboxes, that shortens the gearbox significantly, by leaving the entire center differential section off, and locking the concentric lay-shaft and front prop shaft together with a splined collar.
http://www.bremarauto.com/products/s...onversion-kit/
They are in Australia, and do have some experience with RWD Subaru mid-engined powered race cars, as they are the australian contact for Saker Sports Cars.

[BrandonDrums]

Brandon,

Do you know if you can mate an EJ257 block to a 5MT?

Yes, I've done just that in my car...I have an EJ257 swapped into my 05 wagon using the stock 5 speed...

Bell-housings are one thing but the width of the tranny where the outputs for the half-shafts as well as the length and girth of the transmissions are drastically different. FFR might be looking to provide a drop-in 2wd conversion to replace the center diff which is quite easy to do as well. The 6 speed's DCCD is much more difficult to mess with to get 2wd out of.

Mainly though, the 6mt probably won't fit in the transmission tunnel they have designed for the chassis and it might be sticking out too far back.

The 6 speed isn't THAT much longer but it could cause some issues.

[MDRex]

http://www.andrewtechautomotive.com/

Andrewtech Automotive is considered one of the best Subie tranny shops. They rebuild and upgrade Subaru trannies with PPG gear sets. There is also the option of the Sti-RA 5-speed trannies and gear sets.

[audsyn]

+1 to Andrewtech. PPG gears are widely believed to be the strongest.

There's plenty of demand among WRX drivers for the STi 6-speed driveline, including the driveshaft and rear diff and sometimes the rear driveshafts, hubs, and brakes (assuming those won't be donor parts). OTOH, it's cheap to pick up a worn or busted 5-speed, and this will will offset a lot of the cost of the new gears.

[BrandonDrums]

The 2 suggestions above are solid. As for installation you can also just have any subaru or reputable transmission shop perform the swap. However, I maintain that on this car you really don't need to beef up the transmission because it simply won't see the stresses it does in it's original 3300lb AWD form. The best justification for the gear set is to swap in a taller 1st and shorter 2nd gear which matches better with the power delivery of these engines.

Brandon

Thanks for the explanation. It makes perfect sense.

If I am going to replace the 6 Speed with a 5 Speed I would like to get one that has been rebuilt to handle more power and heavy abuse. Know of anyone that specializes in building heavy duty WRX 5 Speeds?

I still would like to know about 5 Speed trans rebuilders that may add strength and dependability to the 5 Speed. Know of any?

[Jack FFR1846]

Something else that can be had with PPG gears is to run straight cut gears. The whine from them make the car sound all business. I have not driven a car with them but instructed a NH driver who had them in his STi up at NHIS and they sounded quite cool. They are also quite robust as he ended up rolling that STi one winter and transferring the tranny to a newer STi, where the gears still live today. He's one of the later NESIC Track Whores but has done a bunch of COM events.

I guess this is the same reason why many people (me included) run T-5's in their FFR roadsters.

[Benji]

Something else that can be had with PPG gears is to run straight cut gears. The whine from them make the car sound all business. I have not driven a car with them but instructed a NH driver who had them in his STi up at NHIS and they sounded quite cool. They are also quite robust as he ended up rolling that STi one winter and transferring the tranny to a newer STi, where the gears still live today. He's one of the later NESIC Track Whores but has done a bunch of COM events.

I guess this is the same reason why many people (me included) run T-5's in their FFR roadsters.

That's a matter of personal taste. Personally it just sounds to me like you are driving everywhere in reverse

[MDRex]

You can also run straight cut gears for just 1-2, or also 3-4, the higher gear or gears can be normal so highway cruising noise ins't insane.

[Gollum]

Many claim the STi's 6 Speed can handle over 500HP and considerable abuse.

I'll claim a LOT more than that. But it'll be just that, my claim. But I've witness them handle over 500 to the wheels, which with AWD power losses... I'd daresay it's one of the beefiest AWD transmissions around.

There's also no guarantee yet where the 5 speed trans will break. There's also no guarantee that the 6 speed trans won't be able to be used if you want to convert it to FWD only on your own, without FFR's supplied parts. Because it's not too much larger overall, it should "fit" it's just the matter of making it work in application.

Also, heres a site where you can get an idea of what the prices are for gear kits:
http://www.rallispec.com/prod_trans.htm

You'll have to use a 5 speed flywheel/clutch when using a 5 speed, just like using the 6 speed on a WRX requires the use of a STI flywheel and clutch. Same bellhousing pattern on all engines, and same crankshaft teething.

Odds are you will find that 300-350hp is a very happy place for these motors, and your sti motor will do that fine. The 5 speed will most likely hold up to track use, but I'd still wait to sell the 6 speed until we have more details. The good news is that most sti trannys for for a solid 3k, which could be used towards upgrading a 5 speed with better gears and a LSD.

[Benji]

Isn't the six speed a lot heavier than the five speed? 818kg people..... :P

[C.Tree]

Who sells the limited slip for the 5mt? I think most 5mt are not ls. Thanks!

[thebeerbaron]

Who sells the limited slip for the 5mt? I think most 5mt are not ls. Thanks!

Lots of people sell them. They're made by Quaife, Cusco, and eBay's favorite OBX. Google "wrx front lsd".

[forced4]

I have a Quaife in my 5-spd WRX and love it.

[crobin4]

STi also has a helical diff for the 5spd that is basically a slightly smaller version of the helical in the 6spd. Boxer 4 Racing sells them for certain as does Rallispec. they are around 900-1000 dollars. A KAAZ 1.5 way clutch-type is also a good alternative for the same money. If you get the OBX make sure you get the upgraded spring washers and housing bolts (about 30 dollars). They are good to 400HP with that mod.

[Cooluser23]

Dave, Jim

I am pleased to read that I may use the 300HP engine from the donor 2006 WRX STi I purchased last week. I am disappointed that I cannot use the 6 Speed transmission.

From what I read the WRX 5 Speed cannot handle high horsepower and abuse. Many claim the STi's 6 Speed can handle over 500HP and considerable abuse. I am building this as a track car not a daily driver so high horsepower and abuse must be handled by a rugged transmission.

It seems the 6 Speed is the logical choice. Does FFR have a source on hardened 5 Speeds? I would prefer FFR give builders a choice between 5 or 6 Speeds.

Thanks for your time

+1. Please do a 6 speed, so we can use a single donor engine+transmission.
I know there is a company that makes 5 speed adapters. I've mentioned them in another thread: http://thefactoryfiveforum.com/showt...andard-or-auto

I know of a company that makes a fwd adapter for the 5-speed. Not sure if there is anybody making one for a 6 speed yet, or if Factory Five made their own adapter.

Factory Five could contact www.bremarauto.com and see if they may be interested in making an adapter plate for the 6-speed transmission.

[Cooluser23]

Isn't the six speed a lot heavier than the five speed? 818kg people..... :P

I was wondering what the "818" stood for. In that case I really like the name. It's much more global than lbs measurements.

Also, if anybody asks, we can say it's right in the name.

Can we add a small "kg" symbol next to the 818 to make it even cooler?

.
___________________
(of course please update the number with the weight of the final production spec, so it's accurate. )

[bu11dogg2]

Don't be afraid to pick up a engine/tranny combo that includes a 6speed.

The 6speed typically comes with the ej257 and can be traded for a 5 speed and you'll get cash on top, lots of it.

5 speeds typically sell for around $300-$1000 depending on miles.
6speeds sell from $2000-3000 depending on miles.

Gear Ratios

WRX 2.0l models:

Automatic transmission gear ratios:
1st - 2.785
2nd - 1.545
3rd - 1.000
4th - 0.684
reverse - 2.272
final drive ratio - 4.11

Manual transmission gear ratios:
1st - 3.454
2nd - 1.947
3rd - 1.366
4th - 0.972
5th - 0.738
reverse - 3.333
final drive ratio - 3.90

2006/2007 WRX 2.5l models:

Automatic transmission gear ratios:
1st - 2.785
2nd - 1.545
3rd - 1.000
4th - 0.684
reverse - 2.272
final drive ratio - 3.90

Manual transmission gear ratios:
1st - 3.454
2nd - 1.947
3rd - 1.366
4th - 0.972
5th - 0.738
reverse - 3.333
final drive ratio - 3.70

2008 WRX 2.5l models:

Automatic transmission gear ratios:
1st - 2.785
2nd - 1.545
3rd - 1.000
4th - 0.684
reverse - 2.272
final drive ratio - 3.90

2008 5speed manual
1st 3.166
2nd 1.882
3rd 1.296
4th 0.972
5th 0.738
final 3.900


2009 WRX 5 speed manual
1st 3.166
2nd 1.882
3rd 1.296
4th 0.972
5th 0.738
final 3.900


2010 WRX 5 speed manual
1st 3.166
2nd 1.882
3rd 1.296
4th 0.972
5th 0.738
final 3.900



Impreza WRX STi models:

2004-2006 manual transmission gear ratios:
1st - 3.636
2nd - 2.375
3rd - 1.761
4th - 1.346
5th - 0.971
6th - 0.756
reverse - 3.545
final drive ratio - 3.90

2007 manual transmission gear ratios:

1st: 3.636
2nd: 2.235
3rd: 1.521
4th:1.137
5th:0.971
6th: 0.756
reverse - 3.545
final drive ratio - 3.90

2008 STi 6 speed manual
1st 3.636
2nd 2.235
3rd 1.521
4th, 1.137
5th 0.097
6th 0.756
Front final gear ratio: 3.9
Rear final gear ratio: 3.545

2009 STI 6 speed manual
1st 3.636
2nd 2.235
3rd 1.521
4th, 1.137
5th 0.097
6th 0.756
Front final gear ratio: 3.9
Rear final gear ratio: 3.545

2010 STI 6 speed manual
1st 3.636
2nd 2.235
3rd 1.521
4th, 1.137
5th 0.971
6th 0.756
Front final gear ratio: 3.9
Rear final gear ratio: 3.545

[16g-95gsx]

Excuse me if I'm not that experienced with subaru drivetrains, but will the transmission handle any serious power if it is converted to a 2wd mode? Obviously the center diff itself is taken out of the picture, but you are now focusing ALL of the stress on just the "front" diff/outputs. While a 6spd may be able to handle 500awhp, how much force are they able to handle if all of that load is focused on only the front diff? As my screenname implies I'm a DSM guy at heart, so high powered awd drivetrains are something that I am used to, but pricing, weight, and power potential are all heavy considerations on this car IMO and these drivetrains won't be placed under the same load conditions as a normally weighted, 4wd subaru platform.

[bu11dogg2]

It's not a matter of HP and more a matter of how it's driven to a certain extent.

I know plenty of people running 300WHP on the 5 speed that have no issues. I know other with stock power, 190whp, that have blown them up.

I'm not gonna bother with a stock 5 speed only because I plan to drive the car like it's intended to be driven. I definitely plan on going with a PPG'd 5 speed.

[Twinspool]

The load that the transmission 'sees' is reflected back from the tires. You're not focusing the same load at one differential, there's less mass, and less tractive capacity to reflect the load back through only two tires opposed to all 4.

As with so many of these questions, a free body diagram reveals all!

[Gollum]

I don't believe FFR will be using a rear diff at all, as they're probably be using the front wheel trans outputs for the rear wheels. This means a R160/R180 comparison isn't really required learning for any of us here (though I'm a Z guy so trust me when I say I'd love to have that conversation).

The 6 speed has seen pretty stupid amounts of power, and in a FWD only configuration, it "should" be able to handle more power as far as the gears are concerned, but the front diff will be under a lot more stress. This will be offset to some degree by the weight difference, about half of what a fully loaded STI is.

I'm really eager to see how much of a difference a front LSD conversion will help these cars. Most open diffs' spider gears aren't happy with one legged burn outs and the last thing we need to see is a ton of blown front diffs because people were flogging their cars the way God intended.

[bu11dogg2]

Thank you for clarifying that for me

one more part I can sell off in the part out.

[Brian Apple]

#1 problem with WRX 5 speed trans under higher torque load is the case flexes (bows out). This causes less tooth engagement and thus stripped gears. Differential is not a problem in either trans. Sti case does not have the flex problem. This is why the desireability for the STI trans is high. 2wd and less ability to hook up so much torque MAY help, but be aware of the problem.

[mug23]

Bring this back from the dead. So is FFR very certain that this car will be 5 speed only? I would really like use all my parts from my 05 STI as I have a brand new fully build motor and a totally rebuild 6 speed with 5th and 6th JDM gears and the trans since the rebuild has 0 miles on it.

I have also found this kit for the 6 speed to be converted into 2wd mode and that can be used for the 818 if people want to use the 6 speed instead of the 5 speed.

http://www.possumbourne.co.nz/trans_diff_parts.html



I'm also hoping that I can use the STI wheel hub as well and reuse my few sets of wheel with 5x114.3 wheel pattern.

[bromikl]

Mug,
metalmaker measured the 6spd trans, and compared to the 5-speed, it's about two inches longer. So he believes the six-speed will be an option.

But in reality, your options are limited only by your fabrication abilities. Whether or not the six-speed is supported by FFR, some guys will figure out a way to do it.

[Xusia]

For some reason I thought it was 8 inches longer...

[mug23]

Mug,
metalmaker measured the 6spd trans, and compared to the 5-speed, it's about two inches longer. So he believes the six-speed will be an option.

But in reality, your options are limited only by your fabrication abilities. Whether or not the six-speed is supported by FFR, some guys will figure out a way to do it.

I'm sure that if you put time into something, almost anything can be done. I just wish that FFR will provide the option of using either the 5 or 6 speed so it can be a plug-n-play deal.

[Xusia]

This is just the initial release of the 818. In the future, I'd bet real money they support more engine & transmission choices. FFR has a good history of this. If you look at the Roadster, it initially supported only a few engines, and now it supports a wide variety. Give it time...

[whitetiger]

not sure if anyone mentioned this, but the 4th gen Legacy GT spec B came with a version of the STI 6mt but with an open front diff a standard VLSD center center(no DCCD). it also has a taller 5th and 6th gear. this is the box id use for the 818. just need a front LSD from a STI 6mt installed.

spec.B 6 spd manual
1st 3.636
2nd 2.235
3rd 1.521
4th 1.137
5th 0.891
6th 0.707
final 3.900

[Etos]

There's nothing stopping people from using the 6 speed outside of cosmetics. It's definitely not 2 inches longer especially considering I don't believe you can take off the tail of the 6 speed where you can with the 5.

There's alot to consider with the 6 speed though. One is weight, it's VERY heavy and will be the rear most object in the car. This could make for a tail happy car especially with tons of power. With the 5 speed the F/R ratio is I think 40/60, I can see that being further skewed to 35/65 with a 6 speed. Then there's making the 6 speed 2WD. It can be done but it's an added cost.

Honestly unless you are building a drag car that can benefit from weight on the back for traction, anything involving a track with turns should avoid the use of a 6 speed. Just get a PPG 5 speed if you're running stupid high HP if you want to bring it to the real track. You can find used PPG 5 speeds for just a little more then a 6 speed now.

[PhyrraM]

not sure if anyone mentioned this, but the 4th gen Legacy GT spec B came with a version of the STI 6mt but with an open front diff a standard VLSD center center(no DCCD). it also has a taller 5th and 6th gear. this is the box id use for the 818. just need a front LSD from a STI 6mt installed.

spec.B 6 spd manual
1st 3.636
2nd 2.235
3rd 1.521
4th 1.137
5th 0.891
6th 0.707
final 3.900

I'm thinking the opposite. I'm thinking that the extreme light weight of the 818 we will be wanting longer 1-3 gears. First is already too quick on a stock 3200 pound WRX, the 818 will have a virtually useless first gear. In fact, I can see the possibility of 2nd turning out to be the gear of choice for drag racing because of boost, time to shift, and traction issues. Also, who is really going to need a 150+ mph final gear in a street 818? A longer 5-6 would be nice for cruising and NVH, but little else. IMHO, of course.

[Mechie3]

Also, who is really going to need a 150+ mph final gear in a street 818?

Well, you see, when I'm late for work.....


My plan for now is a stock (gear wise) 5 speed. Debating doing the front diff. One thing I've considered is having my busted 5 speed rebuilt with a LSD and keep the other stock trans to swap in/out if I feel like it (or need to if something breaks) or have a second to experiement with.

[wjfawb0]

For daily driving the STI 6 spd was annoying. I skipped gears a lot in those cars. I agree that better spread higher gearing would be better in the 818.

[RM1SepEx]

I'd like taller gearing for my 5 speed... what options are there for final gearing vs. the stock ratio? I'm planning on a Quaife so it has to come apart... I'm also thinking that at 2000 lbs with me in the car 1st will be useless.

[apexanimal]

the 6spd is longer than 2" over the 5spd...

it's going to be a hard fit... i don't think it's a viable option...