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Old 02-11-2013, 01:45 PM   #1
xluben
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10.9s @ 126mph

Default 6 Speed Swap: 2011 STI 6MT with Spec B Long Gears into a 2011 WRX

************************************************** ***
EDIT 1:

The car now has a new motor/turbo setup and makes around 600WHP.

http://forums.nasioc.com/forums/show....php?t=2484865

************************************************** ***

EDIT 2:

Added info on the R180 Rear Diff, STI Driveshaft, and STI Axles swap.

http://forums.nasioc.com/forums/show...3#post39696583

************************************************** ***

I recently finished up a 6 speed swap in my 2011 WRX. The car has about 480WHP/500WTQ from a Blouch 20GXTR on E85 (27-28psi peak, 24-25psi readline). Last June it broke the stock third gear while I was on the road course. I replaced the gearset with a set of stronger gears from PAR. Here is some more info on that:

http://forums.nasioc.com/forums/show....php?t=2378816

I used their newer "650HP" set of synchronized gears. I originally had a straight cut first and helical 2-4 (stock 5th), but then switched 2nd to be straight cut as well. I chose to do a built 5 speed over a 6 speed swap due to complexity (much easier) and because I liked the 5 speed ratios. Here is some more info on the car overall:

http://forums.nasioc.com/forums/show....php?t=2078765

Recently I started toying with the idea of changing things up. Not because I was unhappy with what I had, but because I wanted something different. Mainly I wanted to try limited slip diff's and/or a DCCD as well as shorter/closer gear ratios. Looking into LSD's for the 5 speed, I eventually decided that with these goals the OEM 6 speed made the most sense.
At this point I started researching everything I would need, and also trying to choose the parts I wanted. There have been a few other 08+ WRX's that have done this, so they were of great help to me. This is what I found as the very least that would be needed to complete the swap on an 08+ WRX:
Quote:
Originally Posted by d4rce
04/05 STI trans (complete with clutch release fork, slave cylinder, clutch line, etc)
any STI trans mount
any STI starter
any STI clutch/pressure plate/flywheel + 3 extra flywheel bolts
08+ STI shifter linkage/shift knob
08+ Impreza driveshaft, automatic
DCCD controller
Transmission fluid
There may be other little things, but those are the main ones. That's the minimum list. You can certainly do more. Late 04 (early 04 had axle stubs) and 05 STI tranny's are the easiest because they use a 3.9 rear diff. The downside (for some people) is that they have the short gearing. In general, this is usually the cheapest way to do things. 04-05 STI tranny's can be found used pretty easily, but with varying levels of wear and varying prices and you keep your stock rear diff and front and rear axles.

If you switch to a 3.54 FD rear diff, then you can use any 06+ STI tranny. The 06 is still the short gears, but the 07+ have the longer 2-4 gears. For a 3.54 rear diff you can use an 02-05 WRX r160 or an STI r180. The r180 is stronger but requires custom axles, Spec B axles, or STI axles. If you go with STI axles, then you need to change the hubs, brakes, wheels, etc. Same for the front. If you want the STI axles you have to out other components.

I decided that I wanted to keep things simple. Use my stock hubs, axles, brakes, etc. So it basically came down to 04-05 STI (cheapest/easiest) or 06+ STI and 02-05 WRX rear diff with 3.54 FD. I went out and basically was just letting prices dictate what I would get (but also considering gear ratios and mileage). I contacted many people. Mostly private sellers. I was close to buying two different 04 STI tranny's and then very close to getting an 06 STI tranny. But none of them were working out how I hoped (slow shipping, poor communication, didn't have all the parts, etc, etc).

Part of the decision I had to make was what ratios I wanted. I was thinking that it might be fun to try to short gears for a while. They're a very big departure from the long 5 speed gears. I made many plots comparing the different gearsets and ratios that I was considering. To me the USDM STI ratios are all somewhat of a compromise. 04-06 are very tight 1-4 and then a big gap to 5 and 6 (but 6 is actually shorter than the WRX 5th). This would be good for someone who needs close spacing, but that wasn't really what I wanted. Here is a plot of the WRX 5MT vs the 04-06 STI 6MT:



The 07+ makes 2-4 a bit longer, but 5 and 6 are the same. This is a little better but still not ideal. 4 and 5 are very close to each other. The ideal ratios, IMO, are the Spec B ratios. They are longer 2-4 like the 07+ STI, but they also have longer 5 and 6 so all the ratios are evenly spaced. I figured I could upgrade to the Spec B ratios after I tried the normal STI ratios for a while. They seemed to be what I really wanted at some point. Here are some more gear ratio comparison plots:







I eventually found a 2011 STI tranny available with low miles and in great condition. It was obviously more expensive than what I had been looking at, but I thought it would be worth it to get something so much newer. At this point I had the option of installing a 1:1 viscous center diff (50/50), or keeping the normal 1.1:1 DCCD. The 1:1 center diff would have allowed me to use my stock 3.9 rear diff and I wouldn't need a DCCD controller. But I chose to keep the DCCD because that's one of the things I wanted.

Also, I needed to decide if I wanted to have the SpecB long gears installed. Since this is an 07+ tranny with longer 2nd-4th already, I would only need 5th and 6th replaced. If I were getting an older tranny I would have just held off and gotten the long gears later, but since it already had the longer 2-4 it made sense to do it now. I had RalliSpec open it up and install the long ratio gears. They also replaced the 3rd gear synchros, upgraded 4th-6th to the stronger carbon synchros, replaced the 3rd/4th sleeve&hub, and replaced the 3rd/4th shift fork.
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Last edited by xluben; 04-29-2013 at 10:22 AM.
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Old 02-11-2013, 01:45 PM   #2
xluben
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Default

So, with the 2011 STI tranny it has a 1.1:1 center diff, which requires a 3.54 FD rear diff. I decided to go with the simple option and stick with the r160 in the rear, instead of the r180. The 02-05 WRX r160 is a 3.54 FD, so that is what I got. I also picked up a used 08+ AT driveshaft, 08+ STI shift linkage, ACT clutch setup, and some other small things. Here's a complete list of what I used:

Used 2011 6MT transmission
- 3rd Gear Synchros
- 4th-6th Carbon Synchros
- 3rd/4th Sleeve & Hub
- 3rd/4th Shift Fork
- 5th Drive Gear 6MT Long Ratio
- 6th Drive Gear 6MT Long Ratio
- 5th/6th Driven Gear Cluster 6MT Long Ratio
- Woodruff Key, Adapter (Wide shaft keyway groove)

ACT XT 6 Puck Clutch
- ACT XT Pressure Plate
- ACT 6 Puck Solid Disk
- ACT TOB and Pilot Bearing
- Resurfaced OEM Flywheel
- STI Clutch Fork
- STI Clutch Slave Cylinder
- Braided SS Clutch Line

08+ STI Shift Linkage
- STI Shift Linkage Bushings
- STI Front Shifter Bushings
- STI Rear Shifter Stay Bushing
- STI Shifter Lever
- STI 6MT Pivot Bushings

Other
- Transmission Crossmember Bushings
- 08+ Impreza AT Driveshaft
- R160 3.54 Final Drive Rear Diff
- Heavyweight Shift Knob
- STI Starter

I decided to do the TIC/Kartboy shifter and bushing combo because it would be easy to do while it was all out of the car. The 6 speed lever is a bit more work to get installed than the 5 speed, but overall it wasn't too bad. Having it outside of the car wasn't really all that much easier, except for a few parts (front linkage bushings).

For the clutch I chose the ACT XT with 6 puck unsprung disk. I previously had the ACT HD and 4 puck sprung disk in my 5 speed. It chattered quite a bit, but I needed it to hold the torque. On the 6 speed I considered a twin disk, but the cost and frequency of rebuilds turned me off from it. The ACT is simple and can hold the power. The cost of a new disk is quite low. I chose the unsprung disk for lower mass on the tranny side (a little bit easier on the synchros).
The install went pretty smoothly. I've pulled and installed the 5 speed. clutch, driveshaft, rear diff, etc before, so most of it wasn't new. Just different parts. Pulling this shifter linkages completely out was new, but that was straight forward. The clutch setup (pull vs. push) is also a bit different. Also the 6 speed is much larger and heavier than the 5 speed, but with a tranny jack it wasn't too difficult to get it all into place.

FYI - All the connectors are plug and play. No issues there. The stock shift boot and boot insulation can easily be modified to work with the 6 speed. All I used was a scissor and some careful placement/folding and it looks like a perfect fit (see photos below).

Overall I am very, very happy with it. This shifts are so precise. I don't know how much of this is due to the full bushing and shifter kit, and how much is the tranny, but I do know that the 5 speed never felt this good, even with shifter and front and rear bushings.

The clutch pedal is noticeably heavier than it was with my other setup, but not too bad for daily use. I have the clutch delay valve removed (as I did with the 5 speed), and I find that this setup actually chatters less than my old one. The unsprung puck style disk grabs extremely quickly, but as long as you keep the revs very low and let out the clutch fast/smooth it is pretty easy to deal with.

The gear spacing is great! 1-5 are all just a bit shorter than they were with the 5 speed, so acceleration seems a bit quicker. 6th is longer than 5th was, so it's nice for cruising. So far I think this is a great set of gear ratios for daily driving and higher powered track cars.

Right now I'm still running the center diff open, but I will installing the DCCD Pro soon, and I can update at that time.
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Old 02-11-2013, 01:46 PM   #3
xluben
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Default

And now some photos of the parts used in the swap. Supporting parts:



















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Old 02-11-2013, 01:47 PM   #4
xluben
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Default

I didn't take too many photos during install, but here are what I have of the tranny/car.



















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Old 02-11-2013, 01:47 PM   #5
xluben
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Default

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Old 02-11-2013, 01:47 PM   #6
xluben
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Saved 2
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Old 02-11-2013, 01:59 PM   #7
JarHarms
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Good job, it is pretty apparent that you did ample research beforehand.
Billet 3/4 fork or oem 3/4 fork?
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Old 02-11-2013, 02:02 PM   #8
xluben
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Quote:
Originally Posted by JarHarms View Post
Good job, it is pretty apparent that you did ample research beforehand.
Thanks!

I want to thank Nuke and Fuji from NF Performance for all the help (guidance and actual install help)!

Also, monkiboy, 2011boostdwrx, and Dave @ RalliSpec for the help/tips along the way.
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Old 02-11-2013, 02:03 PM   #9
xluben
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Quote:
Originally Posted by JarHarms View Post
Billet 3/4 fork or oem 3/4 fork?
OEM fork.
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Old 02-11-2013, 02:10 PM   #10
monkiboy
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great photos and information as always, sir! glad it worked out as effortlessly as planned.

one thing i did want to mention that is not correct/accurate from your post above:
Quote:
Originally Posted by xluben View Post
The r180 is stronger but requires custom axles, Spec B axles, or STI axles. If you go with STI axles, then you need to change the hubs, brakes, wheels, etc.
you can install the r180 with STI axles and you do NOT need to change the hubs, brakes, wheels, etc.

i have the r180 installed on my 08 WRX with the 05 STI 6MT using 09 STI outers and JDM v7 inners (any 05-07 STI inners will work). i believe i mentioned this to you in our discussion, but perhaps my memory fails me. i got the idea from another member who has been running the similar setup for over 30k miles without hiccup. it's a great solution.
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Old 02-11-2013, 02:21 PM   #11
guitarman19853
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Awesome post and pics. Always enjoy reading your write ups!
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Old 02-11-2013, 02:36 PM   #12
mikereiser
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Good info in this thread, thanks. Looking to go 6 speed eventually.
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Old 02-11-2013, 02:58 PM   #13
xluben
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Quote:
Originally Posted by monkiboy View Post
great photos and information as always, sir! glad it worked out as effortlessly as planned.

one thing i did want to mention that is not correct/accurate from your post above:

you can install the r180 with STI axles and you do NOT need to change the hubs, brakes, wheels, etc.

i have the r180 installed on my 08 WRX with the 05 STI 6MT using 09 STI outers and JDM v7 inners (any 05-07 STI inners will work). i believe i mentioned this to you in our discussion, but perhaps my memory fails me. i got the idea from another member who has been running the similar setup for over 30k miles without hiccup. it's a great solution.
OK, so you need custom axles, but you don't need the hubs/brakes. I must have missed that in our conversation. That sounds like it would be an option at some point, but the r160 and stock axles was by far the easiest choice.

Quote:
Originally Posted by guitarman19853 View Post
Awesome post and pics. Always enjoy reading your write ups!
Quote:
Originally Posted by mikereiser View Post
Good info in this thread, thanks. Looking to go 6 speed eventually.
Thanks.
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Old 02-11-2013, 03:12 PM   #14
mikereiser
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Any difference between sedan an hatch as far as driveshaft length or anything?
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Old 02-11-2013, 03:13 PM   #15
xluben
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Quote:
Originally Posted by mikereiser View Post
Any difference between sedan an hatch as far as driveshaft length or anything?
No. All the same.
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Old 02-11-2013, 08:19 PM   #16
IMPREZA GUY
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So Sexay!
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Old 02-11-2013, 08:47 PM   #17
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awesome compilation of info, thanks.
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Old 02-11-2013, 10:21 PM   #18
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awesome write up.
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Old 02-12-2013, 12:59 PM   #19
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Amazing write up as always!!! I think your judgement of going with a 6spd to get the LSD & have some differential adjustability is the right call. I have researched the aftermarket cusco LSDs fairly extensively and it just looks like tons of money and technical hurdles to get it in a 5 speed. Nothing like a little better gas mileage cruising and more gears when driving with some pace...

Very excited to see the DCCD go in, great work Ben!!
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Old 02-12-2013, 01:15 PM   #20
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Awesome job. Its good to see people do things the right way the first time. That thing YANKS in 2nd and 3rd gear. Really neat!

*I thought you were selling everything and going back to stock? Or was that just a joke (I kinda figured you were just going bigger turbo personally)?
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Old 02-12-2013, 01:59 PM   #21
xluben
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Quote:
Originally Posted by IMPREZA GUY View Post
So Sexay!
Quote:
Originally Posted by SenorDucK View Post
awesome compilation of info, thanks.
Quote:
Originally Posted by mrfunnni View Post
awesome write up.
Thanks!

Quote:
Originally Posted by mkvaron View Post
Amazing write up as always!!! I think your judgement of going with a 6spd to get the LSD & have some differential adjustability is the right call. I have researched the aftermarket cusco LSDs fairly extensively and it just looks like tons of money and technical hurdles to get it in a 5 speed. Nothing like a little better gas mileage cruising and more gears when driving with some pace...

Very excited to see the DCCD go in, great work Ben!!
Yeah, the DCCD was very appealing to me, so overall I figured it was worth it. The 6 speed swap took a lot more research/time to source all the parts, but I'm happy I did it.

Quote:
Originally Posted by mtarr07 View Post
Awesome job. Its good to see people do things the right way the first time. That thing YANKS in 2nd and 3rd gear. Really neat!

*I thought you were selling everything and going back to stock? Or was that just a joke (I kinda figured you were just going bigger turbo personally)?
I'm selling everything and going to Stage 1. But I put the tranny in before I decided that.
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Old 02-12-2013, 10:45 PM   #22
mrfunnni
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Didnt want to thread jack but xluben said to post it here.

If i choose to do the 6spd swap it would definitely need to include the r180 (track and auto x the car) xlubens stated that you could run the STi axles, with that my question being when you install the sti axles and hubs are you only doing so on the rear?

If i were to capitalize on the moment and install axels front/rear and hubs with the supporting components (lets say oem Sti brembos) i would then be converting form 5x100 to 5x114.5 which is appealing to me as i can run sti bbs' without adaptors and have a wider and lower cost of replacing wheels and not have to wait 4 months for a new set or what have you.

With that being said would the whole suspension need to be revised? (buying sti coilovers and selling the wrxs)
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Old 02-15-2013, 09:04 AM   #23
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awesome write up xluben!
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Old 02-18-2013, 09:51 AM   #24
BroBroBroBroBro
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yep! very well written. The contributions you make help people like me who are relatively new learn and progress with current stuff thats going on.
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Old 02-25-2013, 09:03 AM   #25
guitarman19853
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Any update on the DCCD install?
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