SG9 Forester STi 6 Speed Swap
Whoa, that's a small amount of words to sum up quite a large amount of work. Let's first discuss the WHY before we jump into the HOW.
Why a Forester STi 6 speed? Well.. because of the gearing. The entire reason I put off a 6 speed swap for YEARS was because I LOVED my V4 STi transmission's gearing. I had driven pretty much every 6 speed Subaru had to offer, and I hated how short they were. It felt like I need to shift 12 times just to get out of my driveway. I won't do the gearing comparison here, because we all have access to the trans charts and Excel, but basically the gearing in the FSTi 6 speed was only around 4% shorter in gears than my V4 5 speed. 4% I can deal with. For some context as to other 6 speeds I have driven, the V7 and V8 STi transmissions are somewhere to the tune of like 14% shorter. That's too short.
So that's part of the why.
Why the other parts of the why?
Front LSD, and rear R180 LSD. Bingo bango. I could have spent the same amount of money (alright, let's be honest, a bit less) on an S201 or type RA V Ltd trans of the 5 speed variety to get that front LSD, but that involved waiting for the deal to come up, with the clutch slipping and me racing in (as of writing this down) less than a week, I needed something that was a bit faster. The FSTi 6 speed will do.
Cool. Makes sense. It's the same transmission, but different in all the best ways.
Moving on to the how.
The how portion get's pretty interesting, and I am sitting down drinking a wonderful Final Absolution made by Dragonsmeade while writing this, so I apologize in advance if as you read things makes less and less sense.
I started by trying to get a hold of J-Spec Auto to see what kind of deal they could get me on one of their 6 speed swap packages. They had two Forester STi packages listed on their site, and I had my eyes on a particular one. Unfortunately, it was a holiday weekend so of course no one was around and I just said "screw it, I need it" and bought the one on their website. 3 text/email/phone calls to my bank later, I assured them the $5000 purchase from the internet WASN'T fraud, and I happily awaited my swap package.
When I got everything in, I began to pull it apart and inspect everything.. and the part that really sucked, was that they shipped me something compeltely different than the package they had listed online. Crap. It was still the proper FSTi trans, and R180 rear hubs and differential and all that stuff.. however it was missing a few things from the listing online, had rusted to hell rear hubs, and two of the same side aluminum control arms. I wasn't too upset as I wasn't planning on using most of the stuff anyways, but the rusted R180 hubs themselves prompted a few emails to J-Spec. I had also planned on having proper stuff from the package I had bought online so I could sell it and recoup a lot of the money I didn't want to spend on stuff I didn't really need. I'll get more into the rest of this later.
A week or so later, the new hubs they sent me came in the mail. They were much better.
This allowed me to start to get to work.... except you may be asking yourself... how was I going to use the Brembos with the current wheels I have on the car? If you weren't asking that, then you already know what I was doing.. I was planing on keeping the 4/2 pots. In order to do this, I needed to use the elusive Group N rotors. How do I get my hands on them? Well.. all sources showed an OLD part number. When I contacted Japanparts asking if they could get that part number, the informed me that a new part number was in their system and gave me that number. I looked it up, and it brought me to STis Group N parts list for use of brakes with 15in wheels. Perfect. I ordered a rear set of rotors ($330, ouch) and those came in the same day the new hubs did.
As you can see in the pictures, they are the same outer diameter as my R160 2 pot rotors, but they use the larger 190mm R180 e brake inner.
Perfect. I put in the rear diff, and using my old tried and true bolts instead of diff studs, and mounted it all up.
I also got in the R180 5x100 hubs. To do this, I reused my current GC ABS sensors. They mounted up the same, however had different connectors inside the car. Not really a big deal, but it was easier to reuse em... plus the importers had cut the sensors... even though they didn't show that they did in my swap package
R180 on top, R160 on bottom.
Mounted up the 2 pots and everything bolted up perfectly. The dust shield is a bit larger, but who cares.
Another thing worth mentioning... e brake cables. I can't remember what the rules were, but I was under the assumption that the R180 handbrake cables were only compatible with R180 hubs, so I used them. As it turned out, they were too short and I couldn't attach them to the handbrake inside. I ended up having to swap back in the R160 handbrake cables... which I really think are just GC cables. So, GC requires GC handbrake cables... whodathunk?!
Here's a picture of the couple inches of difference in the cable.
Next up was to front of the car. Pulled the exhaust, pulled the older trans, etc etc.
When I pulled the driveshaft I realized how long it's been since I had touched this drivetrain (I was 19 when I put it in). I forgot that GCs didn't use the spacers like the GDs/SGs did. Unfortunately, even though the pictures the importers had sent me of the swap package included the proper spacers... they were missing, but I didn't think much of it because I figured I could have just used the ones that were on the car... yeah no.
I asked a local buddy (Tsidreams on here) if he had some spare spacers laying around, and luckily enough for me he did!
While everything else was out, I also took the time to check the up pipe to turbo gasket that I thought may have been leaking and replace it. Yeah....
While it was all part, I took the time to put on the flywheel as well as install a brand new OEM clutch disk, pressure plate, and throwout.
With that done, I got to the heavy lifting.
I hate putting 6 speeds into a car from the bottom, with the engine already in, by myself.. but at least this time I had been able to FULLY drain the transmission so I was able to lift it in with dry sketchiness instead of wet sketchiness.
Next up was the new front hubs. I needed to use the ones that came with the swap package because I needed the male style trans end axles, they were already in the hubs, and they used an axle side tone ring, instead of my old Phase 1 style tone ring around the outside.
While it was out, I also switched over dust shields, changed the ABS sensor mounts and plugs to accommodate for the GC chassis, and on one side installed a new ball joint.
With everything bolted up, I tossed the hubs and axles in. New rotors in the front too, because why not? I had them sitting around and I had warped my other rotors at the race track -_-
Car was all set, just needed to swap out a few more things in the engine bay, and button her all up.
I also folded up my 5 speed boot for the time being to make it at least a little bit presentable.
Next on the list was to replace the clutch master. I had swapped fluid out like a month ago, and it was already pitch black. I could only assume the seals weren't super duper happy, so I picked one up from the dealer.
Unfortunately while I was removing the hardline, I had rounded the nut on it and decided to just order a new one from the dealer for $9. Should also note that I decided to keep using my old clutch slave, and the reason for that is because it didn't have the damn delay valve in it that all newer cars came with. Won't be needing that junk.
Got my sister to help me bleed the clutch, and put did some wiring to mate up the 4 pin connector for the neutral and reverse switches on the trans as opposed to the GC 2 pin connectors. I also pulled out the rear O2 harness extension and routed my wideband harness down the trans side.
It's a bit of a mess with wiring in that area, but at least nothing is going to get melted.
Exhaust and intercooler went on and in the typical Garrett fashion, it was dark, rainy, and half the interior was together... so I went for a drive.
First impressions: I can't tell the difference in gearing between this transmission and my old 5 speed when putzing around, or giving it beans. It REALLY feels like my V4 STi trans with a 6th gear added in. I can't really speak for if the LSDs are working or not, since I wasn't driving like a wildman, but I'll be sure to report back when I can.
Few things: ABS is on.. turns out I forgot to plug the two wheelspeed sensors in the front in, but I was also getting some codes for a rear sensor.. so I'll have to address that when I can. I don't think it's a tone ring tooth mismatch, but rather something dumb and stupid that I have done.
Clutch feels lighter than the 5 speed one, like all 6 speeds do, but it's SUPER fresh feeling and responsive... and seems to want to hold torque which is a great quality for your clutch to have!
I need to go into the ECU cal and put in these transmission gear determination thresholds, as well as tune away any new driveability issues, should they come up. Also during the swap process I found a nut bouncing around right near my knock sensor.. so.. that probably wasn't amazing. I'll report back with tuning related findings later.
Super happy with the work put in on the car though, everything just feels THAT much more crisp.
All the above work took me about 3 weeks, and a lot of that was waiting on parts and being unmotivated after days of work, but all I have left now is general tidying up and bolting back together the center console and what not.
Will report back one I finish up!