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Thread: 1962 Ferrari 250 GTO scratch build

  1. #1
    Senior Member C5GTO's Avatar
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    1962 Ferrari 250 GTO scratch build

    This is a build story about a car I refer to as a “C5 GTO”. It’s a hand built replica (sort of) of a 1962 Ferrari 250 GTO. If you’re not familiar with the GTO, here’s a picture of some at Pebble Beach.



    The GTO below (#3943GT), I was able to get access to for pictures, templates and taking measurements. That's me taking tail light measurements. While GTO’s are rare (only 39 ever built) and quite expensive (one sold for $38.5 million last year), this GTO is still used actively in vintage car races and the rear axle was out for repairs when this picture was taken.



    What’s the C5 part you ask? I’ve made extensive use of 5th generation, C5 Corvette parts in building this car. I sourced the engine, trans-axle, suspension, steering, and brakes from Corvettes of model year 1998 through 2004.

    The reason I say it’s sort of a replica is that in addition to the C5 internal parts, I also had to re-style the body shape to account for a difference in track width of 6 inches. I wanted to use the complete unitized front and rear Corvette suspensions so the track width couldn’t be narrowed. The wheel base is same as original but the C5 GTO is wider. I personally think the ’62 GTO is one of the best styled car bodies ever made, so my basic challenge was to not “screw it up” while making the body 6 inches wider. The most succinct description I’ve heard on the visual difference is that the C5 GTO looks like a real GTO that’s on steroids. Sort of like comparing a 289 FIA Cobra to the 427 SC model.

    I’ve been working on this project for about 14 years now. Why so long, simple answer is, "life happens" and I do have other priorities like family and work. If this is the first time you’ve heard of the C5 GTO, I’m starting the story in this thread not from the beginning but somewhere way down the line. You might have read about the C5 GTO in either Kit Car Illustrated or Kit Car magazines before they went out of circulation several years ago. Word got out to a magazine editor when I decided to do the project and they convinced me to write a recurring build article which I called, “Last Chance Garage”. I’m not a car building professional or professional writer but just a car guy who likes cars not made in a factory.

    The first thing I did when starting the project was to make a plan for the chassis. Nothing fancy but good enough so I could get it reviewed by a chassis builder. His opinion was that I’d over engineered it and he helped identify where I could simplify it. Once you see the actual chassis, you’ll probably chuckle because it still looks like a pile of pick-up-sticks. Here's the chassis plan top view.



    Given where I’m at on the project now, most of the early parts I’ll show mostly in pictures. If you have questions or want more context, please post/ask them. I’ll try to answer the best I can.
    Joel Heinke
    (Classic Roadsters Cobra, Ferrari 250GTO under construction)

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    Senior Member C5GTO's Avatar
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    C5 GTO chassis build

    Here’s some pictures of the space frame chassis. I started by mounting the suspension to a I beam frame and aligning the wheels. I then built the chassis to connect the front and rear suspensions. I had to have the torque tube and drive shaft shortened because of engine set back and a shorter wheel base than the C5 has.











    I designed and built this chassis specifically for this project. It’s the first chassis I’ve designed or built so the jury’s still out on whether it’s a good design or just a mediocre one. I followed the chassis design principles of Herb Adams in his book Chassis Engineering. The main strength and rigidity in this chassis comes from the oversized transmission tunnel/backbone that’s fully triangulated on all four sides. I’ve found that I can’t jack the chassis and raise one tire at a time, two tires always come up. I do get cracks from people that my design looks like the Masserati “birdcage” chassis.



    Front and rear suspension is from a ’98 Corvette. I designed the chassis to use the cast aluminum suspension cradles which use 4 bolts each to attach them to the chassis. Power is driven through a 6 speed transaxle which places a good bit of drive train weight back on the rear wheels. The engine is setback 12 inches from normal Corvette placement resulting in a 55% rear to 45% front static weight ratio. Normally a front engine car is heavier in front than rear but this one isn’t. My goal is to get enough rear tire traction to minimize wheel spin but also get great corner handling as well. A 25 gallon fuel cell is squeezed in at the rear of the car to safety store the fuel.

    Last edited by C5GTO; 05-20-2015 at 11:19 PM. Reason: fixing pic URLs
    Joel Heinke
    (Classic Roadsters Cobra, Ferrari 250GTO under construction)

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    Senior Member C5GTO's Avatar
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    C5 GTO chassis build (cont.)

    The chassis has a built in roll cage meeting SCCA specification. It’s constructed of carbon steel DOM tubing the main structural and largest tubing members being 1.5” diameter. There’s a mix of 1” and .75” tubing used for triangulation. All the tubing “fish mouths” were cut on a Joint Jigger with hole saws in my drill press. All the welding was completed with a TIG welder. I was a newbie at TIG welding when I started the project and needless to say, I’m quite proficient now.

    Here’s the bare chassis after it returned from being powder coated:





    I fabricated the chassis, assembled all the drive train, installed the fiberglass body and wired it up while the chassis was in bare steel. The engine is a 2004 Corvette LS3 crate motor with 405 HP from the factory. It’s topped it with a Magnuson inter-cooled super charger that should bump it up into the 575 HP range. I'll post more engine pics later as there's some other unique mods to it.

    I wanted to make the chassis drivable and verify I had all tabs and brackets welded on before getting it powder coated. After that, I took the whole thing back apart and sent it out for sand blasting and powder coating. The bare chassis with aluminum suspension cradles installed weighs in at 460 pounds. My goal was high strength while also being light weight.



    Last edited by C5GTO; 05-20-2015 at 11:25 PM. Reason: fixing pic URL
    Joel Heinke
    (Classic Roadsters Cobra, Ferrari 250GTO under construction)

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    Senior Member C5GTO's Avatar
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    C5 GTO chassis build (cont.)








    The chassis bottom is clad with .050 3003 aluminum forming a smooth under belly. I used a bead roller to inset some portions and raise areas for riveting to the chassis tubes. In these pictures, the sheet still has poly on it. I plan to leave the bottom of the car in polished aluminum.



    Last edited by C5GTO; 05-20-2015 at 11:32 PM. Reason: fixing pic URL
    Joel Heinke
    (Classic Roadsters Cobra, Ferrari 250GTO under construction)

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    Hi Joel. For some reason i'm not seeing any of your pics. On your first posts as well. Cheers Jose'

  6. #6
    ...................
    Last edited by infinitewill; 05-17-2015 at 09:06 AM. Reason: Double post

  7. #7
    The OP may not have had permission to post photos at the time but they show up on my browser.

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    Hi Joel. This all looks great. Looking forward to seeing the body. Cheers Kevin

  9. #9
    Senior Member C5GTO's Avatar
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    Side window frame

    One of the pieces I needed to complete prior to the general body work was the door window frames. Given the GTO is a Berlinetta (roughly translated means sporty sedan or 2 door hardtop), I needed to establish the window opening for so I could form the roof, A and B pillars. The GTO side windows are 2 pieces of Lexan that slide over one another to open windows.



    I decided to fabricate the window frames from .060" 304 SS sheet so they could be polished out to a shine. The most difficult part on this window frame is the upper back corner that is rounded. I had taken a cardboard template of the original GTO window frame so I knew the final shape I was after. I found a sheet metal shop that had a break (press break I believe) that could form 6 foot channels 3/4” high and wide. This leaves about 5/8” by 5/8” inside the channel for felt and Lexan.

    The pie cut for the upper front angle bend was relatively easy. I knew I couldn't “form” the rounded corner so it was cut and splice time. I cut the desired rounded shape from an old piece of plywood as a template. Here it is in pictures.







    To be continued...
    Last edited by C5GTO; 05-20-2015 at 11:37 PM. Reason: fixing pic URL
    Joel Heinke
    (Classic Roadsters Cobra, Ferrari 250GTO under construction)

  10. #10
    Senior Member C5GTO's Avatar
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    Side window frame (cont.)

    I used a TIG welder to weld the filler piece in. When you do this, be sure to either purge the backside or use SS flux. The TIG argon gas protects the weld puddle but the backside needs protection as well.










    This is the newly shaped window frame being mounted to the door frame.

    Last edited by C5GTO; 05-20-2015 at 11:40 PM. Reason: fixing pic URL
    Joel Heinke
    (Classic Roadsters Cobra, Ferrari 250GTO under construction)

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