Please reconsider STi 6 Speed

[bill@dentsport]

You should also take into consideration that the 6mt is 60+ lbs heavier than a 5mt. In a 1800lb car that is a lot of weight to hang off the rear most portion of the chassis. There are over 10 different companies that make motorsport gearsets (we've worked with 5 of them) for the 5 speed, not including PPG, so the options are out there. If you are building one to drive on the street with ~300hp, the RA gears would work very well. Even the 06+ Impreza or any Legacy GT gears would be better than 02-05 WRX, but the ratios are much less desirable than the RA for a sports car.

[timmy318]

Is there any problem in putting in the automatic transmission? I'm not a car guy and just exploring my options

[wallace18]

Check the other threads. This was discussed before. Anything can be done with time and money.

[NonProfit]

One is weight, it's VERY heavy and will be the rear most object in the car...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.

You'd be a shoe-in at the wheelie competition, though.

[whitetiger]

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.

I agree with you about the gears 1-3.

I have a 05 Legacy gt myself with a front LSD from a JDM 5spd STI installed. Im just worried how much power the front diff can handle alone in the 5mt. Assuming most here will do the equivilant of a stage 2 tune on the 818 (no cats and a tune for around 18psi via Cobb accessport or open-source), peak Tq happens very low in the stock RPM range. that could be more then the front diff and pinion output shaft can handle. Ive already blown out my rear diff twice and both rear axles launching at prosolo autox events on the stock turbo(vf40 in my case)

[Xusia]

Ive already blown out my rear diff twice and both rear axles launching at prosolo autox events on the stock turbo(vf40 in my case)

Then stop doing that! LOL

[whitetiger]

its hard when running r-comps and the r-160 rear. had to upgrade to a ap surtrac in the rear, but thats when my axles went.

im just not convinced the stock 5mt front diff, and pinion shaft can handle the tq made by a turbo 2.5 with the stock turbo making over 300wtq at around 3000rpm.

[Mechie3]

Ive already blown out my rear diff twice and both rear axles launching at prosolo autox events on the stock turbo(vf40 in my case)

Is the WRX any different in terms of rear diff and axles? I launched my car often. Usually all that happened was all 4 wheels would break free for a second (kumho V710's). I ran 21psi peak on the TD04. Eventually the trans broke, but that happened just driving to work.

This was my dyno plot on a dynapak (bolts directly to hubs). Says flywheel, but the values shown are at the wheels.

[metalmaker12]

with the rear section off it is just about two inches, just measured them both

[whitetiger]

Is the WRX any different in terms of rear diff and axles? I launched my car often. Usually all that happened was all 4 wheels would break free for a second (kumho V710's). I ran 21psi peak on the TD04. Eventually the trans broke, but that happened just driving to work.

This was my dyno plot on a dynapak (bolts directly to hubs). Says flywheel, but the values shown are at the wheels.
]

not really different other than it being a lighter car, and the vf40 spools nearly as fast as the td04 but makes alittle more whp. blew the r160 on v710s, then after suretrac and hoosier A6 installed, snapped both rear axles in 1 launch. good thing the 818 does not use the the rear portions of the subaru 5mt drivetrain, but i still makes me wonder how much the 5mt front diff and shaft can support by itself. Putting a LSD in the box may be a must at minimum.

[StatGSR]

with the rear section off it is just about two inches, just measured them both

Your assuming you can have the rear section off like you can on the 5spd. sources have recently confirmed that you cant just put a flat block off plate on the back of the 6spd...

[heinzy]

Does any one know of a good source to identify outer dimensions of engines and transaxles? I am a huge FFR fan, and my next car will most likely be a FFR, probably mid 2013. I am also a huge Porsche fan, FFR's only competition for me, and want to use a Cayman S engine and PDK transaxle. This is why I want to compare to see if room exists.

Much more expensive, but holy cow it would be a fun little car.

[Zodiac]

the 6 speed would be nice but yea the extra weight isn't. plus the biggest problem is getting better gearing. i've looked online myself and could only find that the wrx 5 speed is a 3.9 final gearing and no other options. if anyone finds anyone that does offer different ones like a 3.7 plus higher 1-5 gears i hope they make a thread for it so i find it easy haha

[SkiRideDrive]

I believe the 06 has taller final gearing. Not sure though.

[apexanimal]

Originally Posted by hipowernut
Not if you do it bass-akwards like me >

1) Buy a RA geared 5-speed
2) Sell it because you think the 6-speed will work
3) Buy a 6-speed
4) Buy a 6-speed 2wd locking tube from New Zealand
5) Discover the center diff housing cannot be removed and replaced with a flat block off plate (like it can be with a 5-speed)
6) Realize that the design for the rear of the car cannot keep the center diff housing
7) Go behind my house into the woods with my firearms for target practice upon whatever (it was pretty fun) and learn that I never learn to always expect the unexpected on custom build projects
8) List the 6-speed for sale (see classifieds)
9) Search for another 5-speed to buy
10) Contact Subarugears for their 2wd conversion parts

IMAG1025.jpg

Duh - That's what I get in my learning curve on Subaru. If this had been a muscle car with a LS V8 conversion or a custom made full chassis replacing a unibody front subframe setup I'd have been fine, but nooooooooooooo.

Oh well. Lesson learned. I'll save 80 pounds off the tail of the car. I'll find a 5-speed and put in a LSD and still be smiling when I hit the gas.

some more reading...

[mekeys]

What did they say ???..I'm hoping to bolt one together from a plain old donor..

Mel

[metalmaker12]

lol yea sounds like a plan, i got access to a 5 and 6spd and a RA gearset for the 5 in the works so we will see what myself and Wicked Innovations R.I can come up with for the 6 once i get the kit here