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Chase's cheap six speed conversion

52K views 57 replies 10 participants last post by  BoostinChick 
#1 ·
Figured I'd chronicle this since it'll be a significant undertaking. As I posted on my other thread, I popped the back of my trans off to swap rear Difs, and found teeth everywhere. Ugh... Now I remember why I drove an Sti for two years.

So I want to do this the cheap way. btw, in an 02-05 the swap is much easier, since they already have a 3.54 final rear Dif ratio. This is exactly what you want if you swap in an 06-07 six speed. Plus the clutch slave cylinder stays the same. With the 06, 07 Wrx I need the clutch slave and the 3.54 rear Dif.

The 04, 05 Sti tranny has a 3.90 final drive, which means I would have to source a rear Dif that they never put into a Wrx. Only 2.2 l models got that one.

Also my axles and seals stay the same, the one bonus that comes from an 07.

So here is my to buy list.
06 Sti tranny.
02-05 or Sti slave clutch cylinder. (correct me if Im wrong, but I think the Wrx I is almost the same)
Sti clutch and flywheel and throw out bearing
Sti clutch fork
02-05 Wrx rear Dif (should all be lsd, but I've only had one person confirm that I want lsd not open, advice please)
Sti shifter, linkage, boot and knob
Automatic 02-07 Wrx drive line (was told any Subaru auto drive line will do, advise?)

Feel free to correct, add to or ask questions about my list and plans. The idea is to accumulate the right parts from the start to eliminate down time and wasted money, obviously.
 
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#2 ·
What's involved with swapping from a 5MT to a 6MT? You will need to obtain and install the following components:
1. A complete 6MT transmission.
2. 6MT transmission mount.
3. 6MT shift knob, 6MT shifter linkage, and 6MT shift boot.
4. The drive shaft from a 6MT or the drive shaft from any model automatic transmission equipped Subaru. The stock WRX 5MT drive shaft may also be modified (will need to be shortened) to fit as well.
5. New rear end options:
a. New ring and pinion gears to upgrade the stock WRX R160 rear differential to 3.90.
b. Convert the 6MT center differential from 1.0:1 to 1.1:1 and use the stock WRX R160 rear differential.
c. Swap out the stock WRX R160 rear differential to a stock STi R180 rear differential.
The real decision to a 6MT swap is the rear differential, as going with the R180, though the "better" choice, raises the costs significantly as you need to use the entire rear end consisting of the STi driveshaft, STi rear half shafts, Sti rear hubs, and STi rear discs to include the Brembo brakes. This will also require the use of 17" wheels as well to accomidate the bigger brakes, which for some, may be an additional expense. As well, www.gearboxtech.com sells the parts that let you use R180 inner CV joints and the R160 outer CV joints if you want to use the R180 rear end and not swap over to the R180 hubs/brakes.

http://www.wrxtuners.com/forums/f69/transmission-faq-read-if-you-thinking-upgrading-13846/

^ That is what the unabomber faq has for information.
 
#3 ·
Thanks kirt, although option A for rear ends tells me that that FAQ was compiled before the 06 07's were out. With the 3.54 final out, you have the option to use a r160 without modding it. This makes it much easier, especially for 02-05 owners.
 
#4 ·
Yeah, unabomber made most of his FAQs before the hawkeyes came out. I've never attempted this modification...so, that's the best I can do for help unfortunately.
 
#5 ·
It's all good. I appreciate any input. Hoping to document/ photograph as much as possible so that we have this info first hand on our site.

As of now, I can check the six speed, cross members, fork and rear Dif off the to buy list. :D
 
#6 ·
List looks pretty good. Only thing left to consider is the DCCD if you want to utilize it, you will have to use an aftermarket solution. I know a few people who have done the 6spd swap in their 06-07 and still on the stock rear diff. I also bookmarked this when I was going through my 6spd vs. built 5spd debate and spending hours of research online. Hope it helps you (Post #20) -
http://www.clubwrx.net/forums/transmission-awd/164384-06-20gd-wagon-06-sti-tranny.html

Guy actually put a 6spd in his 06 Wagon.

ansonowicz said:
Here I was, ready to post my writeup and forum goes down for a few days


Here goes, it's a lengthy read:


The project took approx 1 month. I worked on it for a couple of hours 3-4 times per week. I took my time, examined every single bolt, nook & cranny, measured 4 times before cutting, etc.

Well, that last remark was a figure of speech but this was the first time i've ever attempted anything as remarkable....by myself.

Parts acquired:

- 2006 STI transmission (used, 15k mi, center diff is 1.1:1 ratio)
- 2006 STI driveshaft (used 800 mi, so the seller claimed it was an 06
- STI 6 speed shifter assembly (new)
- STI 6 speed gearshift knob (new)
- ACT STi Streetlite flywheel 13.9 lbs (new)
- ACT Streetlite STI clutch kit (used, 8k mi)
- 2003 Rear Diff (freebee...Thanks ERIC! 3.54 ratio, final drive = 3.9)
- Neetronics DCCD standalone controller (new)
- 2 Circlips for 2006 WRX Front Axles (new, dealer)
- 2 compression washers for clutch master cylinder (new, dealer)
- about a dozen M10 x 1.25 pitch bolts (various lengths for bellhousing, turbo studs, etc) with Lock washers and hex nuts

Parts Re-used:

- Front Axles (2006 axles do not require new seals or stubs)
- Rear Axles
- crossmembers
- exhaust hanger (on transmission)
- all wiring connectors & plugs (except one plug)
 
#13 ·
Yes, that is what I am saying. A few people on NABISCO who have done this swap on their hawkeyes have kept their stock rear. I asked specifically when I saw a few 6spd "packages" for sale that were minus the R160 (as I mentioned, I was contemplating this swap for myself). Not sure why, cost savings possibly?
 
#8 ·
I wouldn't do it. The 07 WRX rear diff is quite weak. It was a real problem in the 06-07's. We used to argue on here if the rear diff was a greater restriction than the transmission on 06-07 WRX's. Subaru should not have used that diff with the EJ255 and the 08+ is different if I recall correctly. My memory is the 06-07 WRX rear diff is the same one used in the 02-05 EJ205 powered WRX's.
 
#9 ·
If you ever looked at the WRX rear diff and the STI rear diff. You'll notice that the WRX rear diff looks significantly smaller than the STI. So, just like a lot of other things. I'd think the STI rear diff has to be a bit beefer in strength and weight. Or you can just use it until it blows up/upgrade it. Hell, Lil Shoaf and I think Basco upgraded their WRX rear diffs.
 
#10 · (Edited)
I upgraded mine when I had my tranny rebuilt. My tuner highly recommended it.

**Sorry I was wrong, I upgraded the front in mine. To an Mfactory unit. My rear is stock, and was told it would suffice with my power and goals for the car. I might eventually upgrade it when funds and time are available again.
 
#14 ·
Huh. Well I am trying to do this inexpensively, I am also doing it right. Otherwise id just be stuffing in another stock five. I don't mind changing the Dif later if need be, but at least for now it is getting one of correct gearing.
 
#17 ·
$2900! Seems like a deal to me. The members on NASIOC wanted close to $3k and the trans had 80-90k on them. I saw a few eBay listings where it's the complete drivetrain from an 06-07 for $2,700 or so, but freight shipping was $$$. Good luck with your build and let us know how that 6-spd feels!

P.S. Try dropping over $3k just on gears :(
 
#23 ·
Actually, the 06 07 Wrx are a completely different clutch, as they are a pull style. The 02-05 Wrx has the push style which is the same as the Sti, just slightly smaller. A lot of guys have retained their 02-05 clutch through there swap, but all components must be from the same car. Ie. Pp, flywheel, clutch
 
#27 ·
Sorry Brandon, I don't mean to mean. But, it just sounds like the wrong thing to do one way or the other. Wrong size and not as strong (OEM vs OEM) doesn't sound like a working option for me. Mostly it just the wrong size that would scare me away from it. Not worth taking a gamble on it.
 
#28 ·
Matt your info is probably more reliable. I've read several times that it will work, and I believe I've read a couple accounts first hand that did it. Not 100% sure on that, I just know I've read yes. But you know nasioc, one person might have written it and everyone else is parroting it.

Kurt you werent mean at all Lol. I was just saying hypothetically if an owner had a $600 clutch he might just leave it. But I agree, "the right tool for the job" philosophy is always safest. The clutch kit is my final piece of the puzzle now that I've sourced all the other parts. Unless I find a great deal on a stronger aftermarket Wrx clutch, like really great, then it'll be Sti for sure.
 
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