Mach V Motorsports GC Impreza Swap Project

[Mach V Dan]

Mach V Motorsports GC Impreza Swap Project

Table of Contents (all links are in this thread!)

Sponsors
Part I: Overview
Part II: Choosing Your Car
Part III: Planning the Build
Part IV: Beginning the Build
Part V: The Difficult Middle Part
Part VI: What Fits, What Doesn't
Part VII: It Runs! The End, and What I Would Do Differently

Because this is the beginning of the thread and I will start losing readers soon, I want to first thank our project sponsors (in alphabetical order):

Cobb Tuning
Kartboy
Prosport
Rota
TurboXS
Seibon

Part I: Overview

This is a thread about our shop project car, which is a 2000 Impreza. The chassis code for the 2000 Impreza is "GC," and that's how we usually refer to the car, especially since we need to distinguish it from the later "GD" chassis. (More on the GD later.)

Some of the general history behind how we got into this project is covered in a two-part SubieSport article that should appear sometime soon, and I don't want to duplicate too much content, so I'll leave some of the more general stuff for that. Here I'm going to talk in some depth about what it took to accomplish this build, what I might do differently, and suggestions I'd have for others looking to maybe take on a project like this themselves.


Our project's humble beginnings

Our goal in building the car was to make something relatively cheap that the track-driving members of our shop staff could use at the road course, without risking our more-expensive street cars. We settled on a GC Impreza because they are cheap, and any/all of the recent-model Subaru parts will fit on or in them. We started out planning to keep the naturally-aspirated 2.5 liter engine from the stock car, but one thing led to another, and soon we had an entire swap project on our hands. Specifically, we decided to swap the entire mechanical and electrical assembly from a 2004 STi into the 2000 Impreza.


The donor

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[Mach V Dan]

Part II: Choosing Your Car

Here I'm going to give some advice about picking cars. Which of course, we completely ignored, but you have the chance to actually USE this advice, so read on!

Choose the car with as few mods as you can. I almost always find that I don't like the modifications, or that they're poorly done, or both. Choose an unmolested example if possible.


Look! Already tastefully modded!

Look over the options list carefully. Do you want a car with a sunroof? If it's for daily driving, maybe yes. If it's for racetrack use, maybe not. Are there important differences that might matter to you? (2005+ STi models have 5x114 hubs, which will change your wheel choices, among many other differences...) Would an automatic transmission car be okay? A wagon? These may expand your possible cars to choose from.
Caveat Emptor. (Let the buyer beware.) Our car came with an extra engine (Woo hoo!). Which it needed, because the engine in the car had a loud rod knock (Boo!).

I also learned that GC chassis Imprezas are not really very cheap. Compared to OTHER cars going on ten years old, they're downright expensive. Of course, they have the all-wheel drive thing going for them, but it seems there's more than that going on. Could others have our same idea? Are people hoarding them somewhere in New England? I'm telling you, there's an opportunity to make money dealing in old Subies somehow.

[Mach V Dan]

Part III: Planning the Build

Okay, so now we had two cars. One had an engine that's no good. One had a working engine and...well, the body is a total loss, which is how we got the car for not too much money. If you want to start swapping parts on these two cars, you'll want to have access to the following:

• Storage space. Two cars, both of which look like they belong in the junk yard, are not something your landlord or your neighbors are going to want hanging around outside. Ask us how we know this. Just the parts we took off to sell took up an entire storage locker.
• A welding rig, and someone who can use it. We TIG-welded the dash beam in place, among several other things. We also MIG welded all the seams in the front of the car, although you don't have to do that.
• Subaru Bucks. (Or just plain old regular bucks.) You'll become friendly with your local Subaru parts counter. No matter good your two cars are, you will need more parts. We needed a cam pulley bolt, a zillion plastic fasteners, a cam cover, a couple of hoses, a turbo heat shield, various gaskets, and a bunch of other parts.
• Time. Very much time. Many, many, many hours.
• Dollies. By this I mean a flat platform with casters on it, on which you can put things -- engines, transmissions, gutted car hulks. We bought two rated at 1000 pounds. The wheels folded off each the first time we used them. We welded the wheels back on (see welding rig, above) and they have worked great ever since.
• Lifts. This project would be hard without automotive lifts. Getting the engine and transmission out of one of these cars from the top is not fun.

Engine and front suspension on dolly with custom Mach V improvements (wheels stay on)

You've assembled your space, and your cars, your manpower, and your cash. Now think about what this car is going to be. What is its purpose? Road car? If so, what sort? Commuter? Weekend warrior? Track mule? Road course? Drag strip? Is it intended for competition? If so, under what rules? Some of these questions can be answered as you go along, but many of them will have an effect on what you do from the very start of the project.

For example, we decided our car was going to be for recreational track use, and NOT for all-out competition. This meant we would have track-type safety equipment (like multi-point safety harnesses), but we would NOT have to install tabs to hold the windshield and sunroof in. This decision also dictated some of the stuff (like bumper beams, the rear seat, and carpet) we left on the car just for aesthetics or ease of use.

Since pretty much every part of the car will be disassembled, what parts do you plan to replace with aftermarket upgrades? (This question might better be phrased as "How much money you got?") It would be very, very easy to spend vast sums simply replacing decent factory parts with slightly-better, but far-more-expensive, aftermarket versions. It takes a strong will to draw the line, but it has to be done at some point. In our case we were hemmed in by two resource constraints, which were money (we didn't have any) and time (we didn't have any). We decided to get the car together using almost all factory-issue parts. We could always go back and bolt aftermarket stuff to the car later.

There were a few items that we selected from our own parts catalog. Those included a Seibon carbon hood; TurboXS turbo-back exhaust; Kartboy just about everything in the catalog (including short shifter, front and rear shifter bushings, rear subframe lock bolts and outrigger bushings, and tranny crossmember bushings); Prosport headers, carbon catch can, and exhaust wrap; Paranoid Fabrications fender braces; and Rota Torque wheels in 17x8" size. (After each one of these items, I was shouting, "I swear, that is IT! No more! That's the last mod!")

[Mach V Dan]

Part IV: Beginning the Build

Once we had the two cars together, all the shop staff got really excited, and there was a frenzy of tearing down the two cars, in preparation for merging them.


Removing the wiring harness from the STi. In the parking lot. Your landlord will love you!

Even with a lot of well-meaning help, at this point we could have saved ourselves some time with some additional care and time taken in labeling, packaging, and indexing the removed parts, and in not breaking stuff as we removed it. Some of the casualties of the dis-assembly process included the hood release cable, the STi airbag/horn clockspring mechanism, and several bolts that broke off in the unibody of each car. I did take a lot of pictures, though, and several of those came in handy later when we tried to figure out exactly how things went back together. Also, I should say that the broken or misplaced items were relatively few -- it might be that a lot of extra time and care being meticulous on the front end would NOT have offset that much savings on the back end. But I think there were times when we all wished we had been a little more orderly in the initial stages.


I had installed a metal folding chair as the driver's seat, but they made me take it out.

We spent a lot of time cleaning everything, which was time well spent in retrospect. It's MUCH nicer assembling clean parts, and they're easier to identify (and identify problems with) if they're clean. I discovered Wal Mart sells a 2.5 gallon container of industrial-strength grease-cutting soap for ten bucks. Who knew?

We did spend a few bucks at the Subaru Tech Info web site. A few hours there got us wiring diagrams of both cars, and plenty of other good stuff that paid off big dividends later on during the project.

The GC Impreza isn't known for its chassis stiffness. We set out to add a little rigidity (and practice our MIG welding skills) by seam-welding the front half of the chassis.





Many hours of welding and grinding later, we hauled the chassis over to get the engine bay repainted in Aspen White, which will eventually be the whole car color.



After a couple of weeks we had the engines out of both donor and recipient cars, along with their complete car wiring harnesses. We set about grafting the GD STi harness into the GC chassis, in preparation for installing the engine and transmission.

[Mach V Dan]

Part V: The Difficult Middle Part

Here's where the memory gets kind of fuzzy. Exactly how long did it take to get the old engine bay clean enough so that we could actually take the chassis down to the paint place and have it sprayed white? And how long did it take to painstakingly fit all the GD brake lines in the GC chassis, which was a perfect fit except for that one part where they didn't fit at all and we had to custom-bend them?


STi ABS pump in its new home

And how many cans of Brake Kleen spray degreaser did we use up? And how long did it take to figure out which wires to splice together to get the door locks and window lifts all to work?

(I do remember one recent moment where we had the driver-side door window/lock panel all wired up, and it worked perfectly...except for that the window switch worked the locks, and the lock worked the window switch. Heh!)

There are a ton of details to be worked out during this stage. We decided we'd ditch the climate control and the audio system for our track car, but we kept goodies like the power windows, power door locks, the lights, the wipers, and the ABS system. All of these are different between the two cars, so all of them needed custom wiring. In the case of the windshield wipers, the motor is on the opposite side of the car, so we had to cut and lengthen the wiring harness to reach the wiper motor. The old car had a much simpler headlamp system than the STi, which came with HIDs, so we had to install relays to run the GC headlamps.

There were many operations here that involved heavy lifting and therefore could not be done without help, sometimes a LOT of help. Once you have the wheels off a car it can't be easily moved!


Would the owner of a White Subaru STi please report to the parking lot? Your car is in a loading zone.

Other heavy parts include the engine, the fuel tank, the transmission, and the front and rear subframes.


Readying the STi rear subframe for installation


Bolting the rear subframe in place, with rear suspension, brakes, and diff. All heavy. Note Kartboy Botox bolts at the ready.

All these parts were usually bolted up in place while a few of us moved the part into position. While it would have been possible to do it with just one or two people, it would have been a lot harder and more time-consuming.

Some of the more frustrating little details of the project were things we just hadn't anticipated. Take, for instance, the door locks. We were grafting in everything else from the GD car, including the ignition key cylinder. Why not all the exterior lock cylinders? Ah, because of course the GC and the GD cars use a different sort of lock cylinder. The GD one is more sophisticated, and has three little internal key thingies instead of only two. And that means the barrel diameter is much larger. And that means to put the cylinder into the GC sheet metal would mean carving a larger hole, and all of a sudden we're starting to talk about primer and paint and whether we can get the lock hole shaped precisely right -- and it's not really THAT hard to just have two keys on the ring, is it?

The dome lamp presented another problem. The GC dome lamp grounds to the chassis. A single power wire is the only thing connected to it. The GD dome lamp is more complicated, with a fancy dimming feature when it turns off. That means it no longer grounds directly the chassis, and it now has THREE wires going to it. So if you want your GD implant harness to run a dome lamp, you either have to re-wire your existing GC dome lamp, or you have to install the GD overhead fixture.


The interior comes together

Another thing we learned: You can try your best to prevent a problem, but sometimes things just happen. One example of this is that we were very careful to cover the windshield of our car with cardboard during the welding that went on under the hood. From experience, the hot metal spatter from a MIG welder can pit or even crack glass. So our windshield was not damaged from the direct splash the welding. On the other hand, the windshield ended up cracking anyway, whether from the repeated lifting and flexing of the chassis as we moved the engines and transmission in and out, or from other welding-related heat, we're not sure.

There are a lot of the parts from the GD car that just fit right up. A few things don't fit, like the little folded metal solenoid bracket the bolts to the passenger side of the inside fender, under the hood. It provides a home for the boost control solenoid, plus it has provision for attaching wiring harnesses to it. The GD bracket was what we wanted there, but it had a different layout than the GC one. So we cut them both up and just TIG-welded them together so we had a bracket that bolted in the way we wanted, but held the later-model solenoids and wiring harnesses. Piece of cake!

[Mach V Dan]

Part VI: What Fits, What Doesn't

These are some of the things that I can remember that do and don't bolt from the 2004 STi (and in most cases the 2005-07 as well) into the GC chassis Impreza.

Does Fit:

• Front suspension. (Note that 2005+ STi models have the 5x114 bolt pattern hubs, and that means a different spacing on the front knuckle where it attaches to the front strut. So: The strut and the knuckle have to match.)
• Engine and transmission
• Radiator and fans, although we had to trim the fans
• Front lower engine cradle
• Rear suspension, with the exception of the upper strut mounts. (Short-term we're using GC rear suspension. Long-term we'll probably swap in some coil-overs.)
• Rear subframe and diff mount
• Fuel tank
  
  Comparing fuel tanks. GC on left, GD on right.
  
• All the seats, including the back seat with minor adjustment of the mounts.
• Brake master cylinder, ABS pump
• Center console.
• Interior carpet. (Fits okay.)
  
  Interior closer to completion. Note test light, flashlight. Not shown: Curse words.

Does Not Fit:

• GD dash. We ended up welding in the GD dash support so the dash would fit properly, but we don't think the climate control/heater box would have fit in there. If you left the heater in, you'd have to space out the dash to fit.
• GD lock cylinders for the body. They're too big, as mentioned above.
• Wipers and wiper motor.
• Door cards. The rear doors are obviously a different shape. The front doors actually are the same, but the holes in the metal are in different places. You could bolt in the GD front door cards if you wanted to drill new holes. But then your front and rear door wouldn't match.
• Accelerator pedal. The STi pedal is drive-by-wire. You'll need to custom-build a bracket for it.
• GD steering column. It fits, but the GD steering shaft is slightly too long to fit properly in the GC chassis. We cut and welded the shaft, taking out about a 1/2" of length between the U-joints.
  
  The steering shaft is supposed to end where the two bolt holes are. The blue lines are future cut-and-weld locations.
  
  
  Steering shaft segment, post-operation

[Mach V Dan]

Part VII: It Runs! The End, and What I Would Do Differently

Yep, after a month and a half of many late nights and extra hours, we fired the car up. And yes, it started on the first try, thank you very much.


O thank you, gods of car fortune

We had a light on the dash for some sort of ABS problem, and one for a disconnected airbag, but that was it. We now have a running, drivable car. Now there are only a few tiny little loose ends to tidy up. Like...Get the body work finished.


Paintless dent removal

Repaint the exterior of the car. Get tires mounted up onto the new wheels. Swap the new wheels on. Get the seats permanently installed. Install the race harnesses. Fabricate a harness bar. Fabricate a lower front chassis brace. Align the car. Install a fire extinguisher. Dyno-tune the car. Road test the car. Get the car inspected, and registered for road use. Sell/trade/dispose of the old shell, and all the take-off parts. Empty out the storage locker in the process. I'm sure I'm forgetting a few dozen more to-do items.

Now that it's nearly over, I can look back and give some overall thoughts on this project car. Here are a few things that come to mind right away:

• This project makes NO economic sense. The build happened about as fast as I can imagine anyone could do it, and it still took almost two months. And cost-wise, I'm sure we're WAY over $12,000. You can buy perfectly-good swapped GC cars for that. (Maybe they're not DCCD-equipped STi-implant cars. But still...) Move up a few more thousand, and you can just buy a gently-used 2004 STi. Once you've spent all the time and money on a swap, there's no way you're ever going to get any kind of return on your investment.
• The weight of the car is not as light as I had hoped. Part of the reason the GC cars were light was because they didn't have a whole lot of heavy stuff on them, like huge brakes and heavy-duty six-speed transmissions. Now ours has those.
• It's a pretty cool car, but I keep coming back to conclusion #1.
• I'm glad we reigned in our impulse to make it more and more complex and ambitious. It was hard enough to finish as it was. Dragging it on for more time and far more money would have greatly reduced the fun factor.
• I'm really proud of our whole shop for building the car. Forget logic and reason. We decided to do it, we developed a vision of what we wanted, and we did it. It was fun and interesting for all of us. And hey, it may not make complete sense, but I've seen far more money wasted on much less useful things. Perhaps most-importantly, it didn't bog down into a project that would never be finished, only to rot half-completed in the back corner of some garage. I've seen far too many of those cars. Those cars make Mach V Dan sad.

Mike Gerber, our master technician, said the swap wasn't as difficult as he expected. "Really, most of the parts just bolted right up. The only thing that really took us a long time was getting all the wiring right for things like the doors and lights. Other than that, it all just fits." Easy for him to say. For some of us, cutting and welding steering shafts isn't an everyday thing.

Speaking of Mach V staffers, I'd like to thank all the Mach V shop staff for the huge amount of work they've done on this project. Mike, Will, Evan, Tommy, Clinton, and unpaid intern Larry all put in extra hours for this car, and it wouldn't have happened without them. Thanks also to NASIOC member Acquacow, whose own swapped GC car was our literal go-to vehicle when we had questions.

Anyway, to answer my post title above, I don't know that I would have really done anything differently on this project. We all know a lot more about both cars than we did when we set out on this journey, and given our jobs that will serve us well. We still have a lot of work to get done, but the big stuff is behind us. We plan to have the car at our up-coming Mach V Track Day event. And assuming it survives track day (mostly kidding!), we'll have the car back in our showroom for display and storage, so if you want to peek under the hood, just come by the shop.


Front seats are from an '03 Lancer Evolution. Rears are '04 WRX seats.



Thanks for reading.

--Dan
Mach V

[AcquaCow]

YAY! It runs!!!

Dan, I'll have to come by on Friday to check it out...yet again

-- Dave

[smoSTI]

Great write up and a really cool project for the guys in the shop to be a part of. Definitely will help when a customer has a question about parts and usability between different models.

Get it finished for this weekend, there are only a few more days left.

[foolio]

Glad to see we are not behind schedule on our swap project here at Rallispec. Basicly, same issues. Ours is a GF8 though, it actually use to belong to Miles from RaceComp. A customer purchased it however wanted a swap, so the project has began, we are about 3/4 weeks in. So we should be close in about a week. So about a month to do it right sounds correct. Looks awesome!

Jodie

[stiboss]

great to see another rsti been born....money doesn't look like money any more when you into this project...i spent well over 20k on mine stage 2 protuned and the whole 9, btw great built..ha

[AcquaCow]

I need to remember to bring you my spare front bumper with the FMIC cutout before you go to paint...

-- Dave

[ButtDyno]

Originally Posted by Mach V Dan

• This project makes NO economic sense. The build happened about as fast as I can imagine anyone could do it, and it still took almost two months. And cost-wise, I'm sure we're WAY over $12,000. You can buy perfectly-good swapped GC cars for that. (Maybe they're not DCCD-equipped STi-implant cars. But still...) Move up a few more thousand, and you can just buy a gently-used 2004 STi. Once you've spent all the time and money on a swap, there's no way you're ever going to get any kind of return on your investment.

If it makes you feel any better, I'm sure I've spent at least that on my WRX over the last almost-6 years and it's not half as cool as this thing.

Great writeup Dan! Can't wait to see it in person. Might need to talk to you about your PDR guy too

john

[Mach V Dan]

One last pic of the car on track at our 2008 Mach V Track Day...



--Dan
Mach V
FastWRX.com

[scby rex]

Nice work, what cai is that?

[Mach V Dan]

Originally Posted by scby rex

Nice work, what cai is that?

We custom-made it. It uses a TurboXS short-ram intake as the MAF housing, then some aluminum and plastic plumbing with a 3" K&N down in the fender.

--Dan
Mach V
FastWRX.com

[Mach V Dan]

Our first dyno result. Car has the cold-air intake, catted TurboXS stealth-back with factory STi rear section. No other mods.



Update: Swapped the stock STi axle-back for a TurboXS Ti-tip and made a bunch of horsepower!



--Dan
Mach V
FastWRX.com

[bfreeskier]

Hey finish my RSTi swap and have problems w/ the ABS working. Did you get that fixed and if so what was the problem. My swap looks very simular and I love it.
Thanks.

[Mach V Dan]

Originally Posted by bfreeskier

Hey finish my RSTi swap and have problems w/ the ABS working. Did you get that fixed and if so what was the problem. My swap looks very simular and I love it.
Thanks.

When I took that pic of the dash above, we didn't have the ABS computer (which lives on the back of the glove box) plugged in. After plugging it in, it all works fine.

--Dan
Mach V
FastWRX.com

[AcquaCow]

Dan,

How was your shake-down run on the track? Any issues?

I guess you didn't push it too hard the first day out.

-- Dave

[Mach V Dan]

Originally Posted by AcquaCow

Dan,

How was your shake-down run on the track? Any issues?

It was great! No issues.

I guess you didn't push it too hard the first day out.

Ha! Yeah, right. We had two drivers (HPDE 1 and HPDE 3) sharing the car. We ran twelve 20-minute sessions -- I think we put about two tanks of gas in the car.

Here's Mach V Will "going easy" on it...



I drove one session too -- very fast, very fun.

--Dan
Mach V
FastWRX.com

[smoSTI]

That thing was a beast on the track. Every time I looked back it was either that damn RSti or the dude in the turbo porsche.

[kcook]

i didnt get a chance to meet you ^ i was the only subaru in hpde 2

[Mach V Dan]

Originally Posted by smoSTI

That thing was a beast on the track. Every time I looked back it was either that damn RSti or the dude in the turbo porsche.

It WAS fast! I hopped into the Subaru after driving my Mini all weekend, and the Subaru felt like warp speed. I really had to adjust my driving. It put power down really well at corner exits, too -- it shot out from turn 1 like a thing possessed. Very fun.

--Dan
Mach V
FastWRX.com

[SubaruPartsGirl]

It looks like you guys are making great use of your new shop! Congrats on the build, the car looks great!