"The Next One" - Handcrafted Mid-Engine Sports Car
 

I really appreciate everyone's enthusiasm for Rhythm's fabrication thread. That really shows the passion you guys have for not only your projects underway in your garages but as well as other members' rides. Thanks very much.

This is an all new thread that I'm starting so as to share the progress for 'the next one' - our second hand-crafted mid-engine sports car. Like Rhythm's build, it's something that both my dad and I are involved with...I wouldn't have it any other way.

The Idea

Rhythm was in the final stages of assembly and as crazy as it sounds in the back of my mind I found myself already tossing around the idea of creating a second mid-engine vehicle. However, taking into account what had been learned over the course of the building Rhythm, I decided that if and when this new project began, fabrication would have to be approached from an entirely different perspective.

You may have previously seen that Rhythm’s body was essentially hammered and dollied out entirely by hand. While this sounds impressive and taught me how sheet metal behaves, it was immensely time consuming – not something I wanted to repeat. So an English wheel would have to be bought or built to help in creating the panels. I decided to build one. Also, with 'the next one', a fixture would have to be developed to not only provide a base for shaping the body panels, but to also ensure higher fabrication tolerances. For the non-metal shapers out there these fixtures are usually referred to as bucks and can be created many ways including carving a full-scale shape out of foam or building a wooden buck. To meet our requirements we decided to create a wire frame buck. This buck would provide the flexibility to alter particular aspects of the design features relatively easily if it was ever necessary. To ensure that the buck was always square and remained true during the sheet metal shaping process an extremely rigid frame table was necessary. I dislike doing things over again, so the frame table was designed and built in such a way that it was fully adjustable in all 3 planes and to not only work for this project but for others as well.

Here are a few photos of the table:

http://i1099.photobucket.com/albums/.../INVFT-012.jpg
The frame table is being assembled. The main longitudinal beams are 15ft long - the cross members with fully adjustable legs/pads are 6ft across.

http://i1099.photobucket.com/albums/.../INVFT-022.jpg
The table is kept square with the use of triangulation gussets which work on a friction system. Once the bolts are tightened...thats it...she's not going anywhere. To move the table around, the rear legs pop out and wheels slip into the pockets.

http://i1099.photobucket.com/albums/.../INVFT-032.jpg
With a comfortable height set, sliding jigs are being created to mount the engine/trans, seats, and suspension components. It took a bit..well actaully a lot of work to fabricate the table, but we(my dad and I) wouldn't go back to anything else. And when another project needs to come into the bay the wheels can be installed within a few minutes and the table with what ever is sitting on top is rolled out.

Vehicle Design Overview

Starting out as a fresh sheet of paper design, ‘the next one’ loosely resembles Rhythm. Simply called R2, the lines have been re-proportioned and tightened up resulting in a modern aggressive appearance. Since it’s being built as a driver, we want a final fit and finish that only a metal body can provide. An LS6/LS7 engine mated to a Porsche G50 transmission called for a redesign of the chassis for increased rigidity as well. Rolling on 275/35/R18s in the front & 315/30/R19s rear R2 is 28” shorter, 6” narrower, and a little over 900lbs lighter for a total weight of about 2800lbs. The final horsepower to weight ratio is expected to come in around 6lb/HP.

Here are the specifics:
http://i1099.photobucket.com/albums/...SpecSheet2.jpg

Creating the Wire Frame Buck

Once R2’s final design was established and renderings completed 2-dimensional construction drawings were created. These were then taken to a print shop and scaled to full size side, top, front & rear views and posted on our shop’s ‘build board’. Then the exciting part began. To create the wire frame buck, the wheelbase, engine/transmission, seating position, and front windscreen locations were set using sliding jigs on the frame table based on design dimensions from a common datum point. Construction of the wire frame buck began by simultaneously working with four drawings and translating reference dimensions from the ‘build board’ into 3D and 'stump shaping' steel rods, square-stock, and flarbar to match the appropriate feature curves.

Initial 20 minute mockup... I grabbed some parts from storage to get an idea of the new proportions. Ahh.. no worries, those won't be the final wheels... :D
http://i1099.photobucket.com/albums/...cation02-1.jpg

We're into the thick of it with the fabrication of the wire frame buck. The various lengths of box tubing were fabricated to slide along the frame table, then lock into place at set positions. Other lengths were tacked to them.
http://i1099.photobucket.com/albums/...ication012.jpg

To make room for another job, R2 is rolled out of the bay and covered up. At this point, with most of the wire frame completed, the tarp actually created a temporary surface on the buck and outlined some of the body lines.
http://i1099.photobucket.com/albums/...derWraps12.jpg

Just to clarify, the wire frame is a temporary structure. Once all the inner & outer panels have been created it will be removed and all the panels re-assembled on their own.

It will be interesting to see a new project take shape!

I was on autoblog and i saw this Russian concept car with the most unusual doorshttp://www.blogcdn.com/www.autoblog....ncept-lead.jpg.
That's right, they slide up through the body and cross over in the back.
Wanna give it a try?

Looks like a good start!

Thanks Gents,

It was a huge step forward taking the design from 2D into 3D. The key was to make the buck as accurate as possible since it translates any errors directly to the sheet metal stage...and potentially slow that process down.

It's great to play with concepts...those slide-up doors are trick. R2 has butterfly doors incorporated into the design...on a single hinge. The issue one always has to tackle when creating doors for a hotrod/custom car is in creating a wind/watertight seal with existing production door deals. We're running with two seals - an interior one as well as a knife edge seal around the exterior perimeter.

Thanks for looking.

Excited you're building #2 Nick. I envy your time working with your Dad.

Couple questions/comments:

1- What software are you using?

2- How did you bend & weld the wire for the wireform buck. When I tried welding the 1/4" rod, it pulled and caused a kink in the flow.

3- Do you have any images of the overall design?

4- What are you going to use for the transaxle?

Really cool project. Could you describe your weather seal solution in a little more detail? I'm trying to figure out how to upgrade some ancient weather seals, and am interested to learn more about current methods.

That looks like it will be not only an amazing feat of craftsmanship, but also an amazingingly fast street car. What type of suspension will you be using to keep the wheels on the pavement?

With the weather seal design on R2, there is one rubber that slides over the pinch weld on the cab - like in most cars. This one is fairly easy to incorporate into an opening and can come with molding dyed with a colour that matches your interior.

The second seal goes on the actual door with the use of 'one way" plastic "T" clips below the shoulder line of the vehicle. The upper portion of the "T" slides onto holes in the rubber and the vertical leg pops into holes in the door. Creating the seat for this is much more challenging.

The knife edged seal goes around the top perimeter of the door ... above the shoulder line. This one usually sits in a "C channel and requires the most work to sit correctly, but totally eliminates any wind noise.

For the best way to get an idea how these seals work, drop by your local wrecker with a small section of your original door seals and check out the new vehicles - 1998 and up..for possible fits.

Hope this helps and thanks for the thumbs up.

Its funny, but I enjoy the fabrication process more than driving them... Don't get me wrong though...driving is a blast.

As for the suspension, C5 Corvette control arms, hubs, and coil overs will be used on this project.

With the car's buck back in the shop we're starting to fabricate body panels. In regards to the hood, hatch, and door openings independent wire frame sections were created and bolted into the holes. Decided to start with the more straight forward structural sheet metal components that will support the exterior sheet metal skin.

http://i1099.photobucket.com/albums/...rication12.jpg

Templates are created from drawings, dimensions and the wire frame. Since everything is identical from side to side - only revered... ie. rockers, inner wheel wells, A-Pillars, etc only one template is created and then transposed onto the sheet metal. Depending on the what structural components are being created we're running with 18GA & 22 GA

http://i1099.photobucket.com/albums/...rication22.jpg

This is the rocker cover after being transposed from the template with the interior lip created after being run though the tipping wheel...with a soft lower wheel.

http://i1099.photobucket.com/albums/...rication2a.jpg

The blue line indicates the second exterior bend of the door seal step. The first exterior bend is 11/16" to the left of the blue line...one down and one up.. as per the shape needed.

http://i1099.photobucket.com/albums/...ication162.jpg

Then using a shrinker/stretcher, the lips are stretched and shrunk to create the appropriate curvatures. Doing this a series of times and putting the different pieces together gives you this...

http://i1099.photobucket.com/albums/...ation10822.jpg

Here's a shot of the driver and passenger side door openings. With the wire door frame sections removed, the almost complete jam perimeter panels have been temporarily 'pinned' into place on the buck.

http://i1099.photobucket.com/albums/...rication32.jpg

The beginnings of the rear cab wall. Pieces are laid out on the sheet metal in such a way as to reduce waste, yet created as large as possible to eliminate fitting and welding multiple pieces together.

http://i1099.photobucket.com/albums/...rication42.jpg

Rear wall with final forming complete. The beads put in with the bead roller before the ends were rolled over.

http://i1099.photobucket.com/albums/...rication52.jpg

Rear wall temporarily pinned into place with some self drilling self tapping metal screws to the jams and floor pans which were created earlier. This method allows the piece to be removed if necessary for tweaking. An old seat thrown in to add some perspective inside the cab.

http://i1099.photobucket.com/albums/...rication62.jpg

Creating the drivers side scoop for ducting air into the rads. Once the desired shape is attained with cardboard, it's translated onto sheet metal.

http://i1099.photobucket.com/albums/...rication72.jpg

Completed drivers side scoop shaped, welded and installed. The flange will be incorporated and fixed to the engine compartment's interior panels later.

http://i1099.photobucket.com/albums/...rication82.jpg

http://i1099.photobucket.com/albums/...rication92.jpg

Starting fabrication on the rear hatch's inner structure.

http://i1099.photobucket.com/albums/...ication102.jpg

Taillight housing pieces...from paper to metal.

http://i1099.photobucket.com/albums/...ication112.jpg

Taillight housing formed and welded up. Temporarily tacked into place.

Once the front trough pieces were created they were tacked together.
http://i1099.photobucket.com/albums/...ication132.jpg

Carefully controlling the metal in the heat affected zone(HAZ) while welding the front trough to eliminate warpage.

http://i1099.photobucket.com/albums/...ication152.jpg

http://i1099.photobucket.com/albums/...ication162.jpg

http://i1099.photobucket.com/albums/...ication172.jpg

Tipping one of the flanges on the wiper mechanism cover.

http://i1099.photobucket.com/albums/...ication182.jpg

Using the foot actuated shrinker/stretcher I built used Triumph TR7 clutch & brake pedals to actuate the heads, the curve created after tipping up the flange is straightened on the cover.

http://i1099.photobucket.com/albums/...ication202.jpg

With the pieces installed...it's slowly shaping up.

http://i1099.photobucket.com/albums/...ication192.jpg

Rear hatch perimeter complete.

As a little side note, after completing the front moisture trough...I wasn't happy with the way it looked. So it was redone. http://www.metalmeet.com/forum/image.../icon_wink.gif

Thanks for looking.

Nice work. It is really looking good. Thanks for posting your work. Johnny

Thanks Johnny :D

Work on the vehicle's substructure continues...

http://i1099.photobucket.com/albums/...cation22-1.jpg

Once the rear cab wall was fabricated and located the rear cab mounts were created. Since these will be supporting a little more than 50% of the cab's weight, they have to be tied into the sub structure really well.

http://i1099.photobucket.com/albums/...rication24.jpg

... fabricated and installed. Ran with same gauge as the cab mounts since this area will also be supporting the cab and door hinges.

http://i1099.photobucket.com/albums/...rication26.jpg

Horizontal DOM impact/support beam mocked up.

After temporarily pinning these panels in place work on the doors began...

http://i1099.photobucket.com/albums/...rication28.jpg

Inner door shells tacked together. Exterior skins will be created later and then hemmed over the perimeter flanges.

http://i1099.photobucket.com/albums/...rication27.jpg

Inner door shell gapped and mocked up. They need to be tweaked a bit yet for the seals to fit correctly. Access and mount holes will be created once impact beams, latch and hinge mounts have been fabricated.

coming along nicely

Thanks Richard :D R2's body panels are coming out much quicker than I expected...

Fantastic work, and fasinating to see how you're tackling the inner structure. Very much looking forward to seeing this develop!

Designing the inner structure was a challenge. It needs to tie all the panels together and contribute to the frame's rigidity by acting as a stressed member, yet remain light and uncluttered. Thanks for looking Barry :)