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Old 12-12-2010, 12:20 PM
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heinke heinke is offline
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Default C5 gto

This is a build story about a car I refer to as a ďC5 GTOĒ. Itís a hand built replica (sort of) of a 1962 Ferrari 250 GTO. If youíre not familiar with the GTO, hereís a picture of one while I was making templates and taking measurements. While GTOís are rare (only 39 ever built) and quite expensive, this GTO is still used actively in vintage car races and the rear axle was out for repairs when this picture was taken.





Whatís the C5 part you ask? Iíve made extensive use of 5th generation, C5 Corvette parts in building this car. I sourced the engine, transaxle, suspension, steering, and brakes from Corvettes of model year 1998 through 2004.


The reason I say itís 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 couldnít be narrowed. The wheel base is same as original but the C5 GTO is wider. I personally think the í62 GTO is one of the best styled car bodies ever made, so my basic challenge was to not ďscrew it upĒ while making the body 6 inches wider. The most succinct description Iíve heard on the visual difference is that the C5 GTO looks like a real GTO thatís on steroids. I use a picture of the C5 GTO as my avatar if you are wondering what it looks like.


Iíve been working on this project for about 9 years now. If this is the first time youíve heard of it, Iím starting the story in this thread not from the beginning but somewhere in the middle. If you have an interest in kit cars, you might have read about the C5 GTO in either Kit Car Illustrated or Kit Car magazines. 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, ďLast Chance GarageĒ. Iím not a car building professional or professional writer but just a car guy who likes cars not made in a factory. I wonít repeat here what I wrote in those articles but if youíre interested, hereís some links to a few of the magazine articles that just happen to still be on the web:




In this final article I explain more about what I am trying achieve with the C5 GTO project. I never received any reader response as the magazine just happened to print this article in the last edition of the magazine before they went bankrupt. So if you have an opinion to the questions I ask and want to voice it, feel free to send it to me in a private message. I donít want to side track this thread but Iíd love to hear what people think.



If you read any of the above articles, you probably figured out I elected to build the C5 GTO body out of fiberglass. Thatís a decision that may have been different if made now that Iíve become very interested in metal shaping but never the less itís water under the bridge. I didnít know anything about metal shaping at the time so it seemed like the best alternative. I have been thinking about remaking the doors, hood, and trunk in aluminum but thatís another decision for later. What I plan to post in this thread is information about the metal shaping I am doing on the car.
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Old 12-12-2010, 12:29 PM
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Default C5 GTO - the story continues

So without further ado, letís jump into the project. Hereís a couple of pictures of the chassis in ďgo kartĒ form.







I designed and built this chassis specifically for this project. Itís the first chassis Iíve designed or built so the juryís still out on whether itís a good design or just a mediocre one. The engine is a 2004 Corvette LS3 crate motor with 405 HP from the factory. Itís topped it with a Magnuson inter-cooled super charger that should bump it up into the 550 HP range.



Front and rear suspension is from a í98 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 isnít. 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.


Hereís the bare chassis after it returned from being powder coated:





The chassis has a built in roll cage meeting SCCA specification. Itís constructed of carbon steel DOM tubing the main structural and largest tubing members being 1.5Ē diameter. Thereís a mix of 1Ē and .75Ē tubing used for triangulation. All the tubing ďfish mouthsĒ 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, Iím quite proficient now.


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 thatís fully triangulated on all four sides. Iíve found that I canít 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 ďbirdcageĒ chassis.


I fabricated the chassis, assembled all the drive train, installed the fiberglass body and wired it up while the chassis was in bare steel. I wanted to make it 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.
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Old 12-12-2010, 12:29 PM
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Kerry Pinkerton Kerry Pinkerton is offline
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Looking forward to this Joel. Did you ever get your ewheel finished?
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Old 12-12-2010, 12:56 PM
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Default ewheel

Yes, here's a picture:



This is the english wheel I built using plans from MetalMeet and with some key parts I bought from Kerry. The main frame is 4"x6"x3/8" wall rectangular tubing. The upper adjuster and cradles are from Kerry. The anvils are from Hoosier Pattern. The tripod stand with locking wheels has worked out great. I have limited shop space so being able to move this around is important. With the wheels locked, it stays in place for metal shaping.

From my use so far, it's worked great!
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Old 12-12-2010, 01:30 PM
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Kerry Pinkerton Kerry Pinkerton is offline
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Just got through reading the kit car articles Joel. You write very well. I'd have preferred more photos and how tos but we all know magazines are for selling ads not sharing information....

Really interesting to read how you approached your build. Any scratch built car builder faces the same challenges...some with more success than others. It was interesting how you went about finding body buck info.

Your build faces additional challenges based on the high performance aspect of the car.

I'm assuming most the metal shaping is related to interior panels?
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Old 12-14-2010, 10:10 PM
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Default C5 GTO - belly pan

The beauty of a bare chassis is that you donít have to crawl underneath to work on the bottom. I used my engine hoist to roll it on its side and that made building out the belly pan much, much easier.




I first made paper templates for the large panels and then made them from .050 3003 sheet (still white in these pictures as the protective poly coating hasn't been removed yet). My brother had given me a 4í wide end roll from a news paper printing plant thatís near to him. Iíd recommend news print like this for a cheap source of paper for templates. I used a combination of step roll and 1/2Ē half round roll to bead roll these belly pan parts. Thereís a chassis triangulation member under the half round beads and I was trying to get the belly pan close enough to pop rivet it in place. It mostly worked but I had to use a few shims in a couple of areas. The belly pan edges are hammer formed over the chassis tubes using a rubber dead blow hammer.




The belly pan is completed with a panel down the middle. This panel is attached with nutserts and screws so it can be removed for access. The belly pan is the lowest part of the car and sits about 5 inches off the ground. That leaves no room for exhaust under it. So the exhaust pipes run through the chassis backbone and mufflers are located in the middle of the backbone. After this picture was taken, I took the middle panel to a friend with a punch press and had some oval holes punched in it for air ventilation. I considered louvers but was afraid they just get crush shut on a tall speed bump.

The chassis backbone is covered inside with aluminum similar to the belly pan. Itís bead rolled in a similar fashion for pop riveting to chassis tubes. It was harder to do because of being enclosed. If youíve ever tried to place sheet metal around triangulated tubes, you know what I mean.

The open space in front of belly pan is where the engine sits. The cross member with holes is used for engine mounts. With this engine setback (front of engine is about 6Ē behind front wheel center line), the C5 GTO is almost a mid-engine car. The engine is set low with the oil pan bottom just slightly higher than the chassis tubes and belly pan. In addition, the aluminum suspension cradles are clearly visible in this picture. Lower A arms, transverse composite springs, sway bars, and in front the rack & pinion steering all mount on these cradles. In short, they make great unitized suspension modules with four bolt chassis attachment that works great for custom chassis applications like this.
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Old 12-17-2010, 03:33 PM
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Default C5 GTO - firewall

Iíve chosen an inset diamond tuck pattern to add some texture to panels on the C5 GTO firewall and interior. While doing some research before starting the firewall, I saw some similar things on HAMB (and maybe even here) and I really liked the extra personality it added. First, Iíll start with the tooling/machine and then show the panels at various stages.



Iím using a 24Ē Mitler Brothers bead roller. I built the stand and table attachments myself. Iím 6í5Ē tall so the stands they sell with the machines were too short (and Iím too cheap). The table is really a mandatory addition and Iím surprised they donít sell these as an option. I copied the idea from Ric Campbell (http://www.bigwigracecars.com ) and some pictures he posted on HAMB. The primary purpose of the table is to hold the sheet level in the rolls so you can use your hands to move the sheet in various directions without having to also hold it horizontally. For large panels, it really saves your back as well. I made the table to attach to bead roller with only 1 bolt so itís easily removable. The legs also slip on/off for compact storage.



To do the creases for the diamonds, I had to get a custom bottom roll made. Here to I need to give Ric Campbell credit as I copied the design from a picture he posted. I donít have a lathe so I had to get a friend to make it for me. The top roll is a standard MB tipping wheel.





Iím using .040 thick 3003 sheet for the firewall panels. The first step after cutting the piece from the larger sheet is to layout the pattern. Ultra-fine Sharpies seem to work best for this. Standard/fine point Sharpie makes too fat of a line. To frame the diamond tuck, I use a rectangle with rounded corners and a depth of about 1/16Ē. Really just enough to give a visual frame to define the edge but not much as thereís rigid insulation behind the panel. Iíve found that a delrin step roll is much more forgiving than steel (doesnít show my jerky movements as much) while making the rounded corners.





It took some trial and error to get diamonds sized to look good. Iíd definitely recommend practicing on some scrap pieces to get the sizing and ratio you want. I settled on 1.5Ē wide by 3Ē tall diamonds. At first I was worried about crushing the creases made on first pass when making the creases for the second pass. I tried reducing the roll pressure, moving over the crease and then raising the pressure again. In the end, the easiest and fastest way worked best. Just leave the pressure on and run the rolls right over the other creases. If you let the sheet rock as it goes through the crease, the flattening that occurs isnít really noticeable.





Why did I make two insets in the second panel you ask? This panel goes on a surface with a bend in it. I didnít want to crush the diamond insets when using my Magnabend to bend it.







Hereís the panels installed on the chassis. I did peel the poly off a section on one of them. I elected to use anodized aluminum for the firewall and engine compartment panels. I peeled the poly before attaching the panel to make sure the bead rolling didnít ruin the anodized surface. It didnít.
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Old 12-17-2010, 04:05 PM
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Joel, You project is fantastic, great craftsmanship and attention to detail. Excellent documentation and pictures. Can't wait to see more of the project. Thanks for taking the time to document and post the build.
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Old 12-18-2010, 03:49 AM
2fast4u 2fast4u is offline
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When making diamondpatterns like that you could try to use a skateboardwheel as lower roll. It deforms when you cross a previous track allowing you to make crosspatterns without deforming the old tracks.
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Old 12-21-2010, 01:33 PM
dontlifttoshift dontlifttoshift is offline
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First the whole project is bitchin. There are a couple of girl up here that have a datsun based 250. they used a bmw v12 and converted to right hand drive to authenticate it. Always like that car.

Second, you are way overpowered, should be a good time

Third, The quilted layout. DaTinman on the HAMB did that on a 32 firewall and I thought it was awesome. If remember right he used a tipping die on top with a flatwheel wrapped in electrical tape on the bottom. I am going to make some tooling and try this on my pullmax
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