legacycentral bbs

What are the limits of the RS transmission to put up with power?

I want to give 4.11's a shot. I can't stop thinking about how bitchin it would pull. But my question is about the power holding ability.

Will it handle 250+ whp (I finally want to end up at around 270whp with a tune).

Also, to those with 4.11's in a manual tranny. What's your gas mileage like? How does it pull up top? I'd be afraid of redlining 3rd at like 70mph, and then falling to far down out of the power band to get back in it in 4th.

The WRX clutch and flywheel will bolt into that setup, right?

Does anyone have the gear ratios for the RS tranny?

from this thread over aon NASIOC:
http://forums.nasioc.com/forums/showthr ... did=181343
Manual transmission gear ratios for 2.5 RS:
1st - 3.545
2nd - 2.111
3rd - 1.448
4th - 1.088
5th - 0.780
reverse - 3.333
final drive ratio - 4.11

BAC5.2 wrote:Also, to those with 4.11's in a manual tranny. What's your gas mileage like? How does it pull up top? I'd be afraid of redlining 3rd at like 70mph, and then falling to far down out of the power band to get back in it in 4th.

Granted, I'm NA stock, but 4th gear is so sweet in these cars. I've stayed even with a riced-out old Mazda 626 who downshifted into 3rd while I just left it in 4th.

I just did pretty much 350 miles of straight highway driving this past week, and I averaged 28.3mpg (without a/c though )

5th pulls nice once you get to about 80, where you're sitting at 3500rpm.

BAC5.2 wrote:The WRX clutch and flywheel will bolt into that setup, right?

As long as the RS tranny is a hydro clutch, it should bolt up, yes. THAWA took a hydro clutch tranny and used a cable clutch, but I believe the jury is still out on whether you can use a hydro clutch on a cable-clutch tranny.

I thought you needed a push-type clutch with an unmodified Impreza RS transmission. The WRX's is a pull-type.

I thought the push-type cable clutch was pretty much the same as the push-type hydraulic clutch.

That's not true?

The WRX setup will NOT work on an RS tranny or any push type clutch setup.

We put in an RS tranny, it is the opposite clutch type as ours. You will need a different slave cylinger and a longer clutch hose than what we have in our cars. I had tried to modify the pipe fitting to fit in their slave cylinder, but it leaked. It takes the banjo bolt, were as ours takes the pipe threaded bolt thing.

We made our rubber hose fit (took out the intermediate clutch assembly deal), but it is stretched and it is only a short term plan.

The tranny can take power I've heard, but you'll need to upgrade the clutch. Matt Monsen has 250 chp on his RS I believe.

-Ryan

Doesn't Matt have 150whp in his RS? I think I'm making just a little more than that.

Not worth the effort methinks.

I think you're getting confused mike. There's three types of clutch systems used in subarus, cable push, hydro push, and hydro pull. The actual clutches are the same between cable and hydro push.

We put a stock RS box through some rallies with maybe 220 hp at the wheels. Gravel tends to be more forgiving than tarmac on trannies but still it survived fine.

My buddy Eric has a pretty legit 93 Legacy turbo, built up pretty nice running at around 17 psi and we have a 94 WRX tranny on it. These might have more hardened gears than our North American RS trannies though.

We've also swapped a legacy turbo into an Impreza L. All the research we did led us to believe that all the subaru trannies, 1.8, 2.2 and 2.5 are all of comparable "strength". So far so good on Legacy Turbo power through a little 1.8 tranny. We never dynoed it, but seat of the pants horspower feels very good.

I think most of the people who bitch about poor quality Subaru trannies should just learn how to shift properly. Like anything, abuse it and it will fail. If you actually use the clutch, don't lauch hard constantly, I think these things are fine for decent amounts of power.

Try it, what do you have to loose except some time and money. You wanted to upgrade to an STi gear kit when you finally find the limit of the thing anyway right!

Keith
http://www.franticfour.com

I'll stick with a custom box when I go to upgrade. After seeing a sheared FIRST gear on an RA gearset, I have been kind of soured to the whole idea.

I want to get a WRX case, and just do a custom gear build with PPG Dogged 1st and second (straight cut) and a straight cut synchro'd 3rd and 4th, with Stainless synchros, Heavy Duty bearings, billet steel shift forks, and a nice new clutch interlocker, and maybe a Suretrac or Quaife LSD, and an STI 12kg center diff with a Sutretrac or Quaife rear LSD.

Holy shit, that's a $10,000 drivetrain setup

Maybe on the next car...

Holy shit, that's a $10,000 drivetrain setup

Exactlly, if money is no object you already know what you want. We all WANT that kind of setup. The orginal question however leads me to believe you are like most of us mortals, trying to figure out how to produce the most horepower and reliability our wallets will allow.

I say go with a RS box and see what happens. Treat it right, and I bet it will surprise you. Just my .02 cents