78 Holden Gemini, mini Pro-tourer project.

[DryftKult]

Hi guys I figured I should start a thread just so you can all see what I'm getting myself into.

I'm not sure how many 4 cylinder pro touring cars there are or if they can even fall into that category, but I'm here to give it a try anyway.

I picked this up a little while back, it's not the first one I've owned, I've had no less than 15 of them since I was in my early teens so I know them like the back of my hand.

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The Gemini is a unibody design with no removable chassis components whatsoever aside from the front suspension/steering crossmember. It uses double A arm suspension in the front with a torque tube style rear with coil springs all round but not coilovers.

The initial plan is to get it on the road for the moment and have the seating capacity changed from 5 to 4, this requires approval by the local transport authority and should be a simple process. The main reason for the seating reduction is to make some room for some bar work, as a bonus I think in the end having 4 seats instead of 5 looks more symmetrical.

The new brakes and suspension will be assembled as complete units outside of the car and I'll perform a complete changeover of both at the same time once they are complete.

Plans for the suspension consists of a fully fabricated front suspension crossmember with coilovers and a 2" suspension lift to keep the geometry at the optimum angles and lower the center of gravity.
Amatching 2" lift of the rear suspension which is easily done via shimming the torque tube crossmember up and fabricating some trailing arms to suit, rear coilovers are also an easy modification on this chassis, the differential will also be upgraded with a billet Altra9 L.S.D unit fitted inside the original axle, a set of full floating hubs and the axle will be modified to run 1-1.5deg camber.

A popular brake upgrade on this chassis is to adapt parts from a Holden Commodore, the Commodore shared it's chassis and most of it's standard equipment with the Monaro which eventually made it's way to the states and appeared on your showroom floors as the 4th generation Pontiac Gto.
Wilwood offer tasty yet affordable brake upgrade kits for the GTO but unfortunately not all the parts suit my conversion so I'm not too keen on spending money on a kit when I can only use 1/2 of the parts supplied. The great thing about Wilwood tho is they list all the part numbers in the kit so I have been able to pick out the ones I need and find suitable substitutions for the ones I can't use.

My custom front hubs for the brake conversion are already on their way and I should have them by late September if not a little earlier, I'll try my best to keep you all updated but when I get involved in these projects I find it hard to pull myself away long enough to do much else.

Thanks for reading, and I hope you guys are open to the idea of a mini pro-tourer, and if any others exist, by all means let me know, I'd love to check them out :)

[DryftKult]

A few pics of other gemini's in the typical "Aussie" style of modification, mind you these cars never see any road use.

Take note they all pretty much revolve around making them pretty, reasonable efforts are made on the engines and brakes but suspension and chassis is often overlooked over hear amongst the 4 cylinder crowd.

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[R32Jordie]

my eyes!

[DryftKult]

Terrible isn't it?

I like darker paint schemes myself, but these 3 cars clean out trophies at their targeted car shows.

[WallaceMFG]

A small car like that with a good suspension and brake setup like you're planning will be bad news at an autocross! On a tight course it would be hard to beat

[DryftKult]

They're already pretty well known for their handling with the currently available products on the market, but everyone here seems to focus more on power and "looking cool".

I don't mind the latter 2 but I really want to push the suspension development and see what can be done, to my knowledge no'one here has cambered their rear axle before, all lowering is done by springs which pushes the geometry beyond it's peak performance range, and pinion angles for the torque tube hardly ever get corrected, not a lot of effort made by this bunch.

[Ben@SpeedTech]

I used to have an American Chevette that had big plans for a mini pro tourer, but too many projects and moving across the country said it had to go. I've also wanted to do an Opel Kadett with a turbo 3.0 Buick V6 pro touring style for many years. I probably won't ever really build either, so I can live my dreams through what you're doing.

Good looks, power, and light weight in a good handling package, how can you lose? Good on ya mate! Let's see it happen! Let us know if you need any parts we sell that might help make it work, our sales leader Jay is from down under and we ship a bunch of parts to you guys over there.

My concept artwork and photos of my Chevette and concept art of the Opel can be found in this thread... https://www.pro-touring.com/threads/81595-New-artwork!?highlight=new+artwork

[DryftKult]

yeah mate I've already had a read through your thread, I did a forum search for all the models the chassis was used under just in the off chance that someone had already done it lol.

The original concept for mine was to build it a little tamer than this but with a slight widebody and a matching teardrop camper, plans are still pretty much the same except I've decided to push the car a little further than I had planned, I'll be taking them both on an 8 month trip around Australia once they're done.
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[DryftKult]

I just realized I didn't even mention the engine for the build, so I throw that in here now while it's fresh in my mind.

From the factory the gemini used an Isuzu g161z 1.6ltr sohc 8v 4 cylinder, a common swap is to a larger g180z 1.8ltr or g200z 2.0ltr engine, a local tuner has these engines turning out 400hp reliably on pump fuel, with more extreme versions making between 550-700hp on e85 ethanol fuels.

While I'm happy with the potential of sticking with the same engine family they do have their issues, the g200z has issues with the head gasket blowing out between cylinders 2 and 3 due to those 2 cylinders being siamesed and it also has thinner bore walls, the g180z is becoming difficult to find and much more expensive as it is the engine of choice thanks to it's extra meat between cylinders 2 and 3 and it's tendency to rev a lot more, it has also been noted that the stock cast piston style in this engine can handle quite a bit of power before forged items become a necessity.

Also the timing chain tensioner's for these engines are now only made by one company and recently they have started breaking a lot, not an issue I want to deal with.
The G series engines got an update in the late 80's and became the 4Z series, these were sized 1.6, 1.8, 2.0, 2.4 and 2.6, they are smaller in footprint, weigh less and use a timing belt instead if a chain, goodbye tensioner issues. The 2.4 and 2.6ltr versions are plagued by weak piston design and poor head castings, the 1.6 never made it to Australia, but the 1.8 and 2.0 versions are locally available and have no inherent issues.

I chose the 1.8 ltr 4ZB1, because it has the same bore and stroke as the G180z engines, it also uses the same pistons, these engines are still pretty rare here tho being that they were only ever used in 1 vehicle that just happened to be a 12 seater people mover, but other Gemini enthusiasts tend to go with the 2.0 ltr 4ZC1 because it came with a turbocharger and fuel injection already fitted in most cases, so the 4ZB1 is pretty much never used.

I picked up my engine from a very reputable engine reconditioner, and because he has 4 of them and just want's them off his shelves I paid only AU$388 delivered to my door.
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There's something to be said for being in the right place at the right time. He still has 3 more of these engines, I'm considering buying more of them for spares.
These engines mount pretty much the same as the original, however I'm moving it back 4 inches into the firewall to get the weight further rearward of the axle line as they are quite far forward from the factory, with the shorter length of the engine and the 4 inch shift I'm confident I can get the front of the engine to line up with the axle line if not get it behind altogether.

Still working on my transmission choice at the moment, there are no 6 speeds available that bolt on so I need to adapt something to fit, not much room in the trans tunnel tho but I can widen it a little if need be, will wait and see.

[DryftKult]

I've gone back to the design phase again as I wasn't really happy with the first rendering, plus I've learned some things since then and I wanted to add in some finer details and change a few features.

Still a work in progress.
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[DryftKult]

I've made some changes to my plans.
Current engine is now for sale as I have a taste for something much more powerful.
Also decided to do away with the back seats and thus, no longer needed back doors, this is an easy conversion using doors from a wagon model.
Sorry about all the updates with no actual physical work done, I's start posting pics of the parts as they come in soon :guilty:
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[warpedoak]

That sounds like a cool project. Since you decided to go the smaller engine route, are you planning on building a custom turbo setup for it? Or just no turbo at all? Also converting to a 2 door seeams impressive, do you have to shorten the whole chassis, or just put in a new b-pillar and subsequent bracing where the rear door used to be?

[DryftKult]

Actually I have been planning to use a larger than stock engine the whole time lol, the original engine was a 1.6 and the one I've just decided to sell was a 1.8, new engine is a 2.2 turbocharged.

The 2 door conversion is just a changeover of the doors and b pillar with a healthy serving of rear quarter panel to boot, I've added the kick in the rear window area myself as I think it gives the car a tougher line.

Also the suspension height in that pic is a little excessive, planning on putting it somewhere more realistic after I finish work tomorrow.

[DryftKult]

Ok that's about done, smoothed the entire body and set the ride height at something a little more realistic, currently considering running 18" wheels front and rear instead of the 17" fronts but will wait and see how it looks, if I don't like it I'll use the 17" wheels on the trailer lol.

The bills are almost all sorted, so parts and equipment will be coming very soon, want to be able to dive in after moving house in November :P
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[WallaceMFG]

I like the latest rendering! The 2 door conversion and new stance make it look mean

[DryftKult]

I've just been diagnosed with Hodgkin's Lymphoma, Late stage 3/early stage 4 so unfortunately due to health issues this project will have to be put on ice for a while until my health improves.

Pretty devastated, I was so close to starting this project but close to crunch time my health has deteriorated quickly, now have to concentrate on battling this illness.

[C1ROD]

Hi Mate

To bad to hear about your illness....Love the Gemini project.

I once to had a TD Gemini (Coupe), 2ltr motor, head, cam ,carb and extractors.......Lots of fun in the early years.

If you ever need a hand.....just PM me

Best of luck in fighting the illness.

Cheers
Jas

[DryftKult]

Thanks mate, Already had my first dose of chemo and the doctors are pretty happy with how well I've responded to the treatment so hopefully it'll all go smoothly, transport is the big issue atm though as the chemo radically suppresses my immune system which means I can't use public transport for risk of catching someone elses virus or whatever, so I have to cut some corners and put this thing back on the road quickly.

[andrewb70]

Cool project. Do you guys have Ecotec engines down under?

Andrew

[driveit]

Said a prayer for you. God bless and good luck with the project!

[DryftKult]

we have a few ecotec engines, which one do you mean? :)

And thank you driveit for the well wishes :)

[andrewb70]

we have a few ecotec engines, which one do you mean? :)

In the US, the Pontiac Solstice and the Saturn Redline were offered with a turbo charged 4 cylinder, 2.0L turbo engine (RPO code LNF). Here she is:

https://static1.pt-content.com/images/noimg.gif

It had a pretty awesome torque curve and made 260hp:

https://archives.media.gm.com/us/powertrain/en/product_services/2008/HPT%20Library/Ecotec/2008%20LNF/2008_20L_LNF_Solstice.pdf

It was backed by either an auto or a 5 speed manual:

https://static1.pt-content.com/images/noimg.gif

More details here:

https://archives.media.gm.com/us/powertrain/en/product_services/2008/08car.htm

Give you any ideas? :-)

Andrew

[DryftKult]

looks like a decent engine, but unfortunately no we didn't get them here, most of GM's offerings in Australia are front wheel drive except for commercial vehicles and the commodore/gto/monaro platform.

[DryftKult]

In order to keep myself occupied while I'm laid up at home during my chemotherapy, I have decided to do a few things to make the car just a little more enjoyable to drive.

so I have a spare dash on the way that I'll be recovering, seats and roof lining will follow and I'll also be ordering new carpet, going for a red plush vinyl interior with black accents, and I'm also lowering the car a little and fitting a set of 15x6 and 15x7" smoothies for that classic look. might as well fix the little things until I'm healthy enough to tackle the bigger jobs, but I need something to keep me occupied for now.

[DryftKult]

So my parent's bought a farm, and have a few spare/empty garages...

It's over 300 miles away, but my Stepfather drives between here and there daily for his trucking business so I can hitch a ride easily whenever I want to go up there, and thus I have scored myself a decent workspace.

4 bay garage, 8' ceiling, concrete floor, 3 phase power.

So now I have somewhere to work, but also need this car for daily duties and can't afford to keep it off the road for an extended period of time, so I'll be looking for another shell in the near future that I can take some time with and not rush it.

[DryftKult]

So the doctors told me I couldn't stray too far from a major hospital, this has caused me a small drama as my workspace is about 400km from the closest hospital that can deal with me if I should suddenly get ill, bummer.

I'm halfway through my chemo anyway, on the mend in a big way so hopefully it won't be too much longer before I can get wrenching on this thing.

In the meantime, I've continued mucking about with the cars design, and I think I'm getting closer to the right proportions.
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1.5" roof chop, 3" out of the length of the floor pan to suck the pillars in, all the factory glass is retained with the windscreens converted to flush fit. The rear wheels are enlarged to approximately 20" and are pushed back into the rear quarters to retain the cars original wheelbase, and grafted on a late model rear end.

Something about the old design was bugging me, took me a while to figure it out, there's so much of the rear wheel right under the back doors from the factory, once the roof was chopped it just didn't look right till they were moved back.

Also my efforts to source a Toyota 3SGE Beams cylinder head for a reasonable price has come up trumps, so I've decided to use a 1MZ-FE V6 instead.
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Still trying to figure out if I want to build it as a high revving N/A, or big hp turbo, 600rwhp is easy from these engines with a decent turbo and forged internals.

[DryftKult]

So I got an all clear from my doctors today, after 6 rounds of chemo my tumors have finally vanished :)

It'll still be a couple of weeks before I can go back to work, but it means I can get the ball rolling soon.
The whole experience has left me a little broken, both physically and financially so it'll take some more time to fully recover, but I'm back :D

[Blue70]

Great news!

Can't wait to see this build take place, I like things that are different :)

[NOT A TA]

Congrats on better health! Thats an ambitious plan for body modifications. Always wanted to chop something myself but haven't done it yet. Good luck with the project.

[Justin@EntropyRad]

unique little chassis!

[DryftKult]

Hey guy's, only a few small things happening atm, car is gaining registration very soon as I'm now allowed to drive again.
I've had a sudden change of plan as I have come across a gold nugget while sifting through the dirt, a nugget in the form of a rare Isuzu G180W DOHC 8 valve engine.

These were a japan only offering and only saw homes outside the red circle through private export, they have a reputation for making stonks of power and torque.
I have been speaking to a guy that has one producing 280rwhp on only 12psi of boost, he describes his engine as "mildly modified".

I however am going all out, and have ordered forged pistons and rods (my own specification increasing the rod ratio from 1.63:1 to 1.68:1, not much, but it's a trick I learned building the SOHC versions of the engine that share the same crank, bore and stroke ;) )
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[DryftKult]

Scooped up this Toyota sc14 blower for $50, also came with the Weber 45mm side draught carb attached, that'll either go on the shelf for another future project or get sold off.

I'm thinking I'll use the supercharger along with a turbocharger for a parallel twincharged setup.
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Also, the mega rare camshaft bearings ($800 for a set of 20 shells!) have landed and are at my local dispatch, waiting for the next business day to be delivered.
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[Justin@EntropyRad]

Engine looks like an old Yamaha-built 4age race mill!

The car kind of reminds me of a smoothed over Datsun 510

[DryftKult]

Engine looks like an old Yamaha-built 4age race mill!

Your not far off the mark, yamaha designed the cylinder head on the isuzu mill, the engine is not much different from a 2T-G engine, but different enough to make sure that most major components won't interchange.
The bucket and shims from the 2T can be used in the Isuzu, and it has glorious Hemispherical combustion chambers :D
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You can also run L1 spec camshafts without affecting idle in these engines, L2 spec requires some work to the pistons for clearance but results in a very angry sounding engine, so I'm leaning towards the L2 specs naturally :P

[DryftKult]

Camshaft Bearings Were delivered yesterday.

Man these are hard to find, in japan the classic Isuzu guys are paying over $800 for a set.
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[DryftKult]

Ordered up new carpet, kick panels and tweeters last night.

Needed the tweeters so I can shape the dash and blend them in before I recover it, car gets rego in just under a fortnight so I want it to be comfy.
Carpet is USA red, kisk panels are raw fiberglass and I will be covering them myself.

I chose a set of Pyle Titanium super tweeters, these are going into the dash corners.
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[Godbolt]

Good stuff. You still driving the car or about to start cutting her up?

[DryftKult]

Haha, I'm just about to start driving it about. I need it to get around from a to b to buy and collect all the supplies I need to start making many of the parts.

I grew up around old school hotrod guys in Australia, back in their days there wasn't a great deal of stuff available and almost everything that was available was imported from the states with a huge local markup by the shops selling them, so they all learned how to make things from scratch.

I spent my early teens to my early 20's working in my father and uncles hotrod shop. so I learned a lot about metal casting and how to manipulate steel, but I haven't done any of that in years.

This project has rekindled my interest in the lost arts, so I need to source a lot of equipment, I'm glad I have a towbar haha.

[DryftKult]

Recieved my new carpet and kicks, now I need to stop messing about and sort it out for rego.
It's due to all be back on the street this coming friday, then I can start working on a few bits and pieces to make it liveable/reliable, I have a few suspension mods ready to go on but everything is somewhat temporary as none of it is to be used on the final car, but the 4x4 ride height and skinny as hell tyres just arent working for me. New springs/shocks/wheels and tyres are first on the cards.

[cluxford]

Hey mate, I love those little Gemini's and your plans are awesome. I see you are Brisbane based. You have the fastest 4cyl in Australia up there and it's for sale right now. My fav Corolla, I've had 3 of these and if I weren't pumping all my cash into my new business this one would already be in my Garage (it's for sale right now). Turbo charged 4cyl making over 900rwhp, pulls 8 sec qtrs. Yes 8 secs. It's best is 8.17 @ 169.21 mph

https://www.youtube.com/watch?v=IDxsQH074Vo&feature=youtu.be

[DryftKult]

No sign of my tweeters and they were supposed to be delivered on monday.
Messaged the seller only to find out they hadn't sent them yet, so I got a full refund.

Have now purchased these Pyle PDBT35's.
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[DryftKult]

Well my tweeters arrived, and they look beautiful.
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I started the process of mounting them but I burned out my hole saw (bi-metal my ass) so now I need to buy a new set.
Also bought upholstery chord, leather point needles and a teflon presser foot for the trusty old singer, all I need now is to find a suitable covering material and I can begin the dash upholstery as soon as the shaping is finished.

I also found these, and am considering getting them to fit out all the switchgear on the dash as they match the tweeters perfectly.
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looking for some round vents for the dash, hoping to find something else that matches, or I'll have to whip something up.

[DryftKult]

Finished stripping the dashboard today, have to finish rough mounting the tweeters in the corners then get started on the foam repair and shaping.

I'm fitting a console extension in the center of the dash to make more room for the aftermarket air conditioning unit, controls and car pc 7" touchscreen.
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[DryftKult]

Bought a pair of new old stock lower timing chain tensioners for the twincam engine.
These are extremely rare, and almost impossible to find.
Got them very cheap, as the person selling them didn't know what they were.
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[DryftKult]

Ok lol, I'm starting to lose a little focus here, been buying random bits and pieces here and there and as a result I haven't been able to really get anywhere with this, so time to get back on track.

I need to start driving this thing soon, But the interior in it's current state is a terrible place to be, smelly, old, deteriorated, and extremely uncomfortable to drive so I'm fixing that first.
so far I've fitted the new carpet and stripped the dash vinyl for foam repair and reshaping, and ordered a few new parts.
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With the exception to the dashboard restoration, I now need to get cracking on actually getting it registered before I spend any more money on other parts, my suspension upgrade is still short of a few parts, and I also need to finish saving for my wheels.

I have chosen a set of JNC 010 16x8, if I have worked it out correctly these should fit near on perfect.
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[Godbolt]

Wheels look good. You going polished or black?

[DryftKult]

These ones will be polished, eventually when I buy the wheels for the widebody they'll more than likely be black, but I won't be doing the widebody for some time. still trying to get a hold of the glass needed.

[turbomonaro]

Well done my man, keep the dream
They are cool little cars and will be abit of fun .
Anything you need in the way of connections in Australia that I might be able to help you with.
Please let me know , AD HARDHt monaro

[DryftKult]

Thanks mate, your monaro is a work of art by the way.
My biggest problem atm is budget, I have still yet to return to work as I'm still somewhat recovering, but I doubt I'll be able to return to plastering, so I'm looking at other avenue's.

[DryftKult]

Foam filling prior to sanding and reshaping.
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[DryftKult]

Trimmed off the excess and ready for sanding/shaping
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[DryftKult]

Most of the dash pieces are here now, save for the billet knobs and a few switches.
Sorry bout the crappy photo, poor lighting + phone camera.
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[tonykim]

You have a really cool project. Your car is very similar to what GM sold in Germany as the Kadett C. I love the use of a blower with the weber side drafts if you go that direction. I have lurking in the corner of my garage a '69 Opel Kadett Rallye that I bought 10 years ago and threw a cover over as a future project. Mine has a heavily built 2.0L Opel engine with twin weber 40DCOEs, built suspension, etc. It revs past 7000 rpm easily! Anyways good luck with your project and glad you have work space and your health is better.

[DryftKult]

I've had a few setbacks cash wise, life always gets in the way of project lol.

Have decided that while the "Destroyer" project will be going ahead, it won't be happening with this shell, instead this one will be used as my daily/development car for some of the components to be used on the final car.
A small mishap with the finances means that I'm no longer using the wheels I had originally planned to use, I'll still be looking to purchase them again at a later date but for now I'm looking to use a set of old school smoothies in 15x7 and 15x9, we're tubbing the rear wheel wells up to the chassis rails to gain about 1.5" of extra clearance and shortening the standard axle by 20mm so I can run the 15x9 in the rear without jdm style poke. I'm also considering either using a set of Pontiac fiero 2" drop balljoints and custom tubular upper arms in the front and dropping the spring saddles on the diff about 2" to give it an extra low stance without messing about too much geometry wise.

[DryftKult]

Hi everyone, long time no see.

Well I ended up selling the Gemini and buying a holden Barina as it was more reliable and easier to maintain, I'm back working now and I'm accumulating parts for this build.

I went back to the start and changed a few things, firstly I'm changing from the early TD shape to then next model down the timeline, a TE model.

Main reason is engine capacity. The max allowable engine capacity you can run in Australia is based on the weight of the vehicle, in QLD where I live there is a table that must be followed.

I have some photos to show what's going on but the forum isn't letting me upload them right now for some reason, I'll try to sort it out and upload them shortly.

[DryftKult]

So here's the Later model shape, Americans will recognize it as a RWD Isuzu I-mark
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I've converted it to a 2 door in this rendering, I have glass on the way from Germany for this conversion as GM sold them there as the Opel kadett c, which had a version called a "Limo" which used the sedan shape with the 2 door configuration, the doors are a little longer than the 4 door units.

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Wheels are here, I had the fed-x'd direct from California, yes they are reps, but hopefully in time I'll be able to afford to have a set of forged Rotiform Roc's to replace them, but they will do for the initial build and fit out.
Sizes are 18x9 +30 and 19x11 +25

The rears will require both tubbing and a slight widebody to fit, the fronts will almost fit without work but I plan to widen the front suspension to make room for more steering lock, I'd like to try my hand at a little drifting in this car.