What exactly is it about the evo transmission that makes it capable of holding it's power without breaking? ... or does it break like the 5spd on the imprezas?

I am really curious about this because

1) i plan on doing the wrx swap into my gc8
2) I don't want to spend the money on the 6 spd becuz of slower to 0-60, worse fuel economy in higher speeds, and the cost$!
3) i would like to strengthen the wrx 5spd if possible....

I'm not an aggressive driver doing those ridiculously high rpm launches.... so I don't plan on making the tranny invincible, but simply put would like to keep a 5spd that can hold as much power as the evo or sti...

and please don't suggest dogbox....

 

I really think you should check out some of the treads on the broken WRX trannies. Some of them from what people say break under normanl driving which is scary. There are ways to treat gears (cyro treatment), but i would definately atleast look into getting beefer gears they are out there but you are going to have to search. Good luck, Mario

 

The evo is a transverse motor, so its gearbox is totally out of the question as an alternate- I hope that wasn't what you were asking about.......

BTW my WRX 5 sp tranny has 100,000 miles on it without breaking, and while I haven't gone and done any motor mods, I wouldn't say I've babied it either....

 

1. I would hold off unto you break something after the swap. Unless you're loaded or you're already having problems.

2. The 6spd should have better fuel economy with an extra overdrive gear. Unless I'm missing something.

3. From all the posts I've read the weakness isn't in the materials themselves but from "case-flex." Even people who have changed out the internals with fancy Australian parts have had problems because of this.

 

yeah I've been reading up a lot about this case-flex thing.... supposedly this is just a theory still? but it seems to make sense.

Hm I really have no idea... I was hoping that maybe there was the option of changing the casing of the gears, but that doesn't seem to be a very liable option considering it's going to be expensive as hell too... rebuilding the transmission and all.

the 6mt swap's beginning to look more friendly. I haven't read anybody having problems with that transmission yet. mm I just wish I could find some more tidbits of how much worse the fuel economy is on that thing.

btw I'm not going to do any of this any time soon... broke college students can barely afford swaybars

 

Haha I'm in the same spot. Dreaming of an Sti engine or even an FXT.

 

yeah you are missing something. the 6spd gears ratios are a lot closer together than the 5spd.

its not like they took the 5spd and just threw on another gear. with the closer gear ratios, at say 65mph you will be at a higher rpm in 6th gear than you would be in 5th gear with the 5 spd.

another example is that the 6spd redlines around 135 mph while the 5spd can take it up over 145

 

what?!? i thought you can achieve a higher top speed with 6 spd?!? that sucks

 

nope, lower top speed

 

seriously though, how often do you find yourself needing to go faster than 135?

I'd trade the tractability of the closer ratios in a heartbeat over silly tall highway gearing.

 

with sti mounts and stock internals my 5 speed put up with over 340whp for 1year. Finaly gave way when i clutch dropped her on the street racing my buddies 10 sec mustang.

Trannys rarely break due to mechanical failure induced by power, more often then not its the stupid driver who puts his mechanical equip in harms way by being stupid.

 

Is there any way to make the case stronger so it doesn't flex? I'm gonna assume no, since everyone who is pretty much un-happy with the 5sp just swaps in the 6spd.


Jason

 

does the USDM 6MT have the same ratios as the JDM unit? ive heard that the USDM tranny's 6th gear is a little more fuel efficent friendly than the JDM 6 speed.

 

someone wrote something about putting rings around the case... i'm not quite sure what that meant... but doesn't seem like a very popular thing to do... yeah i could hardly find any posts about strengthening the 5spd case in general.

 

Rings Thats a new one to me. I have heard of guys even talking about welding bars on the outside.

But the best idea i heard yet was a guy talking about getting the 5MT cast and redoing it. Pretty much the inside portion would be the same to house all that is inside, but the outside would be beffer. I was reading about it somewhere but i can't remember. I thinks its a great idea but they where saying that a cast alone and then trying to reproduce another is really expensive. Hopefully someone w/ alot of money, and someone who really loves subaru's develops a cost effective fix.