The last one! #538 is getting V12 and RHD

[DopeOfWelding]

I officially have the last GTM sold! Technically not the last produced though, mine is #538 of 539. Last one for the USA. I’ll try to not bore you all with the details so I’ll give the short version of it.

539 total were produced, but number 538 was an incomplete kit. As of February 2024, 539 was being finished up for a Canadian customer and 538 was just a left over, un-powder coated chassis. I called in late January ‘24 about buying a GTM and was told they were discontinued. I had some very unusual plans for a exotic build I had been wanting to do for the better part of 20 years and explained to the right person at F5 that I really only needed a body and glass for my unconventional build. Although I would entertain buying a chassis if they had one. I was told that the chassis jig had already been destroyed but they could get a body together for me. I got a call back a few weeks later that they had one chassis left in storage that they kept as a possible “final send off” build for the GTM by F5, that they would sell to me. Due to the plan I have for this build, it worked out great that it was an incomplete kit since the parts missing is the stuff I don’t need. I ended up with a damaged body they were going to end up destroying, which also works perfectly for my project. It seemed to me that they were happy the last one they had was going into the hands of someone that could do something with what was left.

Fast forward to the 2nd week of March ‘24 and the GTM was in my shop and on the chassis table ready for surgery.

The plan: Styling updates to bring what is now, a dated looking car into the 2020s. It’s s great looking car, but having been designed in the early 2000s, it shows. The tail light panel and front valance will receive the majority of the make over. I intend on building the car as JGTC car ( Japanese Grand Touring Championship/ GT500) The car will have heavy JDM influence, including RHD conversion which I’m nearly done with already. The body will receive a mild wide-body. Lexan window sliders, rear window will have a scoop. Large dual element, swan mount GT wing. I also have LED Ferrari F355 taillights I will be using.

The power: V12. I have seen many talk about it, but I haven’t seen it done. I have a Mercedes Benz M120 6.0L from a 1994 SL600. Yes, the same long block used in the original Pagani Zonda. It will have the famous titanium equal length headers, ITB, Link stand-alone ECU, 60-2 crank trigger. Backed by a Mendeola SDR5 with 3.88 LSD. Transaxle is done and ready to ship.

Suspension: I already have it in roller status on C5 Z06 arms, sprung by custom QA1 dual adjustable coilovers. I know further tuning will be needed, but a good starting point. Brakes are going to be slotted 355mm 6 piston Brembo.

Wheels: I have Advan Racing GT premium forged center locks for Porsche GT3RS. 19x12 rear, 19X9 front wrapped in Toyo R888R 345 rear and 265 for the front. I’m making cup style center locks to eliminate the goofy Porsche lock mech.

Interior: I have full carbon fiber Bride Zieg IV wide racing seats and complimenting Sparco components like FIA approved 6 point Hans harnesses and steering wheel with Works Bell quick release on a Mazda RX-7 FC column. Dash will custom full carbon as well with custom gauges.

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I hope to keep this thread updated with the build as it progresses. I’m aiming to have the car completed in 2ish years time. This is far from my first rodeo, but given my car is so incomplete, I will be making everything as I go. Certain things I would like to follow the way the car was intended to be built, so I may need to pick some of your brains to overcome some obstacles!

Thanks for looking!

[ohmygosuness]

Very exciting to see how this turns out. Curious to see what chassis modifications you will do to make the V12 fit.

Out of curiosity, when did you place the order for Mendeola? I have mine ordered nearly 3 years ago and I'm still on the waiting list.

[DopeOfWelding]

Very exciting to see how this turns out. Curious to see what chassis modifications you will do to make the V12 fit.

Out of curiosity, when did you place the order for Mendeola? I have mine ordered nearly 3 years ago and I'm still on the waiting list.

The M120 isn’t grossly larger than an LS. It’s the same width, a few inches longer. I will be using a dry sump oiling system so that will greatly reduce the height of the engine. I may have to get creative stealing space where I can by the firewall. I know I’m already going to be swapping from distributor to coil on plug and eliminating the VVTI. Gooichi Motors makes some compact water necks and filter relocation parts. The transaxle will likely be shifted back up to 2” which is fine since I don’t have a transaxle mount with mine. I’ll have to fabricate one.

I got REALLY lucky with my Mendeola. I gave up on using one and was sourcing an alternative as I was told by Mendeola it’s 6 months when I spoke to them in February. Only to find out that many people like yourself wait 1-1/2 to 3 years. I was looking at Ricardo M7003 6 speed. Pricey, but not by a ton more than a new Mendeola. The Mendeola is around $13- $14k now. I happened to be on Facebook marketplace one day and one popped up, brand new in the crate. Struck a fair deal and sent a deposit. It was a blessing since I’m trying to complete this car in 2 years, and it’s greatly hinging on fitting the v12 in it as soon as possible.

[JimStone]

Wow, that's a heck of a plan. Clearly you know what you're doing. Respect to you GTM guys.

[ohmygosuness]

Maybe I should've just done that instead of waiting. It's making me want to cancel the order and get a Porsche trans. I've been itching to make it AWD. But it would need a ton of work.

What ECU are you planning on using?

[DopeOfWelding]

Maybe I should've just done that instead of waiting. It's making me want to cancel the order and get a Porsche trans. I've been itching to make it AWD. But it would need a ton of work.

What ECU are you planning on using?

Finding a Mendeola for sale isn’t too common. I have seen the Ricardo’s come up for sale in the $15-$20k price range. Problem with the G-50s is they are a fortune ($10k for a junk yard core, $20-$25k for a ready to run box) and not as strong as a Ricardo. The M7003 from the Ford GT is really the only other option IMO since they can eat 800hp and ask for more and are the same length as a Mendeola. I believe about 50lbs heavier. Other Ricardo’s such as the one from the Panera are not as strong and don’t take kindly to hard launches.

As for the ECU, right now the plan is to run a Link and add a 60-2 trigger to the harmonic balancer. I know the M120 V12 has support from Halltech, but that maybe a little out of my budget unless I can pick up some sponsors. I just about have my life savings dumped into this car already. Oops

[ohmygosuness]

Damn. G50s really going for that much? I guess a rebuild would put it in the same price range as Ricardo/Mendeola. But at least the Mendeola would come new out of the box.

What made you go for the M120 as opposed to the beloved LS motors?

I just about have my life savings dumped into this car already. Oops

Same here! The things we do to build our dreams...

[VRaptor SpeedWorks, LLC]

Looks like a very ambitious project! Welcome to the madness here.

[Tooth]

Can't wait to see this come to life.

[DopeOfWelding]

I can’t say I have searched every corner of the web for G-50s but that seemed to be the average I have seen over the last 6 months.

As for the M120. An exotic looking car should sound exotic no? At least that was my reasoning. I didn’t want to sit in the car and feel like I was sitting in anything remotely like a corvette. The M120 has a great track record for reliability, puts out a modest 400hp in stock form, forged internals, can be made to scream like a 70s formula 1 car, used in the Pagani Zonda… and I only paid $3,300 for one with low miles!
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[Jim1855]

I like the odd, unique and unusual if it makes sense. This does and should be seriously cool. V-12 has a nice "ring" to it.

A local builder stretched a GTM, installed a LS something motor and a traditional RWD automatic. That didn't make sense to me, but I suppose the trans was cheaper. He did run events like the Silver State.

Jim

[DopeOfWelding]

My Mendeola SDR5 arrived this week! Did a little clean up on the V12 as well as sourced out some go-fast goods that will make it singggg. Also set the car up on the table at “ride height” so I can start making up all new tabs for my QA-1 coilovers. I also bought a small powder coating set up so as I make mounting tabs and such, I’ll just powder them and bake them.

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[beeman]

Are you using the OEM c5 front UCAs? They will make it a challenge to gain camber without losing caster. Less caster means more squirrelly at highway+ speeds. I used the OEM front UCAs but moved the upper mounts towards the rear for more caster and maybe 1/4 inch inboard to help with camber. I now have 8+ available caster and more available camber than I need, I think I set it for like 1.8 to start. I also added anti squat while I was at it to better match the C5 corvette, I added half the angle of the corvette UCA to be conservative.

[VRaptor SpeedWorks, LLC]

Since he has a Gen II, the front UCA mounts are already moved back an inch compared to the Gen I.....

[DopeOfWelding]

The V12 has found its way into the car! Also finished up the pedal box and steering column swap to right hand drive. I still need to address the steering rack but that is actually to simple part. I had to redesign the column mount to raise the column up at least 2” from the stock style mounting location which means it HAD to go right through the dash bar. That spot received some significant reinforcements. I’m happy with the use of the RX-7 tilt column. Did I mention that I’m 6’6” tall?? Between the V12 taking up additional cabin space, the fixed carbon fiber Bride seats, my height and the car having a 39” overall height… I like challenges.

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As for the M120 V12, I knew I would have to make some compromises to make it fit like moving the firewall forward some. I know I was going to have to convert it from distributors to coil on plug. I also removed the water pump and will be using a remote electric pump, that freed up a lot of space. But the most expensive problem that I knew could have been an issue… I have to convert to 5 stage dry sump oiling. I need to get the engine lower. I can lower it 1-1/2” as is now, but dry sump will lower it around 6” significantly improving clearance for the independent throttle bodies (which made the engine taller, but let’s be honest- totally necessary.) the dry sump system in total about $6,500- $7,000. Ouch. Had the cut out the X-brace above the transaxle to fit the engine, but I have a plan for that as well to have a removable brace there.

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[DopeOfWelding]

A few additional photos

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[cob427sc]

WOW! I love this kind of a project, just a little (heh, Heh) out of my retirement budget capabilities. I wish you good luck! I have built various maybe called odd ball or at least different cars along with numerous restores over the years including 7 FFR cars. Just finishing a V8 engine/Bugeye Sprite transformation. Looking forward to your progress.

[VRaptor SpeedWorks, LLC]

Very nice work! Love to see the progress on such a huge project!

[Shoeless]

Hell yea man, keep up the great work and sharing updates. I love seeing stuff like this!!!