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whats a good Transmission for 02 WRX

29K views 17 replies 8 participants last post by  lx1992 
#1 ·
Mine transmission is going out soon hearing some noise from the center of the gearbox. whats a good transmission for 02 wrx? and how much can i get for $1.400? kind of want a sti transmission.
 
#4 ·
I have recently been looking into stronger trans options so, I may be able to shed some light. For $1,400 your not going to be able to get anything except a stock rebuild or a used WRX transmission. I have been shopping around and the cheapest STI trans swap I've seen lately was maybe a tad over $3,000. The STI 6-speed trans is considered by most to still be stronger than a built WRX one. If you don't drive like a mad man though a WRX transmission can safely handle stock and up to stage 2 power levels easily. The 2 most important factors in ANY tranny's longevity is driving style and regular maintenance with quality products. You say your hearing noise from the center of your gearbox? Can you be more descriptive of the noise or maybe even a video. It could be numerous things like your clutch, center diff, or more serious internal problems like a mainshaft, shift forks, or the gears themselves. If it is a clutch component or the center diff then your only looking at 300-500 in parts to fix it. I don't know how much new OEM internal parts are but can tell you that for upgraded aftermarket gears your looking at about 2,000-2,600+ in parts alone just for your choice of 1st & 2nd or 3rd & 4th. All four gears upgraded go for around 4,000-5,000+ for parts alone. The weakness in the WRX transmission that is non-existent in the STI is the case design. The WRX case is split into 2 halves. Under high stress it can flex and cause the mainshaft to flex along with it. This causes the gears to not mesh as they should and BAM! You blew a tranny (haha). There is a company called Moore performance that makes "blast plates" which are reinforcing 3/16 steel plates with high grade fasteners that help to combat this case flex. I just ordered some of them tonight actually. Upgraded gears for the WRX come in the form of factory upgrades like the 05-08 Legacy GT gears found here 2005 - 2008 Legacy GT 1st - 4th Gear Set , STI RA gearset found here STi Standard Ratio Gearset , or aftermarket stronger upgrades like the PPG's found here PPG 5MT Subaru Straight Cut Synchro Gears and other comparable ones made by other companies such as Albins.

The 6-speed swaps can get downright confusing and for this reason, I won't go into great detail. Some things you need to research and keep in mind for a STI 6-speed swap are axles, gear ratios, brakes, hubs, wheels, clutch, driveshaft, dccd, and rear diff's.

Axles: Some of the STI's use male axles and some use female or "axle stubs" on the end that goes in the tranny. STI axles will not go into a WRX hub. I have heard of making a hybrid axle out of one of each (WRX & STI) but, don't know much about it.

Gear ratios: You have to make sure that your rear diff's ratio and trans are going to work together.

Brakes: You need to make sure your brakes will work with whatever hubs you use and if not find some that will like STI brembos

Hubs: As mentioned above WRX & STI hubs and axles won't fit each other.

Wheels: If you do any swap with STI hubs except the 2004 STI your going to either get new wheels or adapt yours because the bolt patterns are different between STI & WRX (excluding 2004 STI which is the same as a wrx).

Clutch: WRX and STI sometimes use different clutch systems so additional parts may be needed here depending on what the swap comes with.

Driveshaft: Either a STI driveshaft or any automatic impreza driveshaft will be needed because of the difference in lengths between WRX & STI.

DCCD: This is the driver controlled center differential but is completely optional and not a must for the swap.

Rear diff: As mentioned above the ratio of this must be compatible with whatever STI trans you choose. I can tell you that the 07 STI trans swap is considered the easiest because the 3.54 R160 rear diff of the 02-05 WRX works with it. In most other swaps you will need purchase the STI r180 also.
 
#5 ·
@ ~84k miles and 300-something whp, I sheared the teeth off of my stock 07 WRX 3rd and 4th gears (banging through them like an idiot instead of shifting smoothly), so I upgraded to Albins helical 1-5 gears. I've had friends who tried to go the cheap route and get stock replacement gears and they went through several sets before upgrading to something strong (like Albins or PPG) and they ended up spending much more money than I did in the long run.

As a precautionary measure @140k, I upgraded my stock clutch to an ACT heavy duty street clutch.

Now I have ~143k miles on the car and 442 whp - no problems with my driveline.

I think my axles are the next weakest point. If those break, I might consider upgrading them to a stronger version, but I might also keep them stock since they're relatively inexpensive and easy to fix.
 
#9 ·
I guess my point was if you're just trying to get the car back on the road again, stock replacement gears would work and be your cheapest option. If you want to enjoy the car for a while and not worry about it breaking again, it's time to invest a little money in it.
 
#15 ·
Whoa! whoa! whoa! Hold up there tiger! Your tranny makes a noise and the 1st thought that pops into your head is a 6-speed tranny swap? C'mon man! let's work the problem! The fine folks on this forum gave me some good advice a while back... "Use the K.I.S.S. method."(Keep It Simple Stupid). At first I was little put off by this comment but the more I thought about it the more it made sense to me. I lost all boost and I was squawking on about getting a new turbo replacement/rebuild when all I needed was a C-clip on my waste-gate actuator arm. A 10 cent part!!!:eek:

Let's start with a better description of the noise. Is it a whine? Maybe a buzz? Or a whirr? Is it constant? Is it in all gears? Does it get louder under load? Can you change the pitch of the sound by putting side or down pressure on the stick without shifting? Does the clutch or brake affect the noise in any way? Is it full/leaking? Is there metal on the drain plug magnet?

My center diff started making noise too at about 96,000mi. I'm the 1st and only owner/driver of my car so if it's damaged "I" did it. I think I did too many J-turns using the hand brake.:( I know it's wrong) but I was having too many Petter Solburg moments.:D The car doesn't drive any different and I'm at 114,000mi now with no change. It's just driving me nuts! Besides, noise is wear so eventually it'll fail so I did some checking around for my problem and I came up with this... Transmission noise fixed! center diff bearing - NASIOC I'm gonna' do this and go from there. Maybe this is your fix too? For less than half of your $1400
 
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