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jdm wrx 5speeds 4.111 fd w/ 3.9 rear end?

Posted: Mon Aug 02, 2010 9:39 am
by JZZ30
so my ss tranny is hooped. There is next to nothing availible for ss 5 speeds. I have looked at 02-05 wrx tranny's but i heard they are "glass trannys"

So i was wondering are jdm 90's wrx trannys any stronger? I'm looking to buy this one.

he says is a version 2 wrx tranny, anyone care to fill me in anything special about that?

http://cgi.ebay.com/ebaymotors/Subaru-I ... 4cf0affe8b

also i am aware that jdm wrx 5 speeds are 4.111 final drive and i have a 3.900 rear diff.


is it possible to compansate for this by using different tires?

I calculated by cross multiplication that if i use 205/55r15 in the rear and 215/60r15 in the front,

25.193"-----23.9"
_____---=--____
4.111--------3.90

215/60r15 tire height 25.2"
205/55r15 tire height 23.9"

the difference in tire height is 7 thousandths of an inch.

Re: jdm wrx 5speeds 4.111 fd w/ 3.9 rear end?

Posted: Mon Aug 02, 2010 6:32 pm
by Legacy777
The WRX trans are just as good as the turbo Legacy trans.

As for the gear ratio difference. You will need to match the trans and rear diff final drive ratio. You can not compensate with tires.

Re: jdm wrx 5speeds 4.111 fd w/ 3.9 rear end?

Posted: Mon Aug 02, 2010 6:37 pm
by SLODRIVE
Dude, PLEASE don't jack your Legacy up (figuratively and literally) with big 'n' little tires! Your idea would "technically" work, to be honest, but you'll throw off the whole balance of the car and negatively affect braking and handling. Plus it'll just look silly, y'know? :wink: Just go find a 4.11 rear diff if you go with that trans, the rear diffs are really easy to find.

Re: jdm wrx 5speeds 4.111 fd w/ 3.9 rear end?

Posted: Tue Aug 03, 2010 4:53 pm
by JZZ30
ya scrap that stupid idea. I found a 02 wrx tranny locally and its 3.90 fd yay!

600 bones though

Re: jdm wrx 5speeds 4.111 fd w/ 3.9 rear end?

Posted: Tue Aug 03, 2010 7:13 pm
by vrg3
Wait, watch out -- the 02 WRX transmission has a 1.1:1 output ratio between the front and rear (or the other way around, I forget). In any case, it's meant to work with a 3.545 rear differential.

Re: jdm wrx 5speeds 4.111 fd w/ 3.9 rear end?

Posted: Tue Aug 03, 2010 10:04 pm
by JZZ30
vrg3 wrote:Wait, watch out -- the 02 WRX transmission has a 1.1:1 output ratio between the front and rear (or the other way around, I forget). In any case, it's meant to work with a 3.545 rear differential.
damnit this is never ending for me trying to match up fd's

ya you're right i just looked it up on alldata

what about 90's wrx tranny's? are they 1:1?

Re: jdm wrx 5speeds 4.111 fd w/ 3.9 rear end?

Posted: Tue Aug 03, 2010 10:22 pm
by vrg3
Yes, I believe they are, but like you say in your first post their final drive ratio is 4.111.

I think you basically have two options: get a Legacy Turbo transmission and drop it in, or get something else and have to swap other stuff too. You should probably decide on one or the other and then go from there.

Do you know about http://www.car-part.com ? Looks like a few junkyards listed there have SS transmissions for $750.

Re: jdm wrx 5speeds 4.111 fd w/ 3.9 rear end?

Posted: Tue Aug 03, 2010 11:33 pm
by n2x4
You could use the WRX transmission if you swapped out the transfer gears.