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

[iNVision]

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:


The frame table is being assembled. The main longitudinal beams are 15ft long - the cross members with fully adjustable legs/pads are 6ft across.


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.


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:


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... [IMG]http://********shaping.com/images/smilies/biggrin.gif[/IMG]


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.


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.


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.

[Rick (madera)]

Just like a house, you have to start with a good foundation!

[rokcrln]

Good deal, I love detailed builds! I to started off much the same way with my coupe/RPU build. My table it 14'x3'-6" and made of 3.5"x3.5"x1/4" tube with a 1/2" x3" plate welded to the top. This plate has 3/8" holes drilled every 3" OC. for bolting in what ever is needed and wanted. I built mine this way because the over all idea is to have jigs for each section of the build so it can be bolted in place and repeated every time for vehicle production. I also started with a full size drawing. Really helps see the end result.

I too am already brain building the next version before the first are even a reality. I have thought of taking the C5 vett running gear but bolting the motor right to the C5 trans axel (I was told it can be done).

Keep up the posts and pics!

Kevin
LFD Inc.

[3 Chiefs]

Thanks for deciding to post this build. I was hoping you would. Your attention to the details impresses me. You cars are well thought out in advance. I think that contributes to your success. Like your first build, I will enjoy this one too. Keep us posted.

Paul

[Hotrod1932]

Looks like it is going to be another really great build Nick. Thanks for your efforts ( and the same goes to all the others here ) to post up your dreams and then let us watch them become real!!!

Part of what makes Metalmeet so interesting and helps keep the "Child" in all of us so excited!

Thanks for posting it!! Then "Drive it like ya stole it!" :twisted:

[iNVision]

Thanks Gents. I thought you guys would like to be included in the build progress.

As you can tell, we're really excited about R2. The frame table and construction of the wire frame buck take all the guess work(frustrations) out of creating the body. Essentially, it a complete vehicle jig. And simplifying the vehicle's design has already saved soo much fabrication time. Without the rear section of the vehicle flipping up...we don't need additional structural reinforcements, pivots, latches..etc. Also, using C5 suspension components not only improves the power to weight ratio and handling, but we don't need to spend the time to engineer a complete suspension like we did for Rhythm. Don't get me wrong, Rhythm handles really well...however, there is a lot of room for improvement when you use steel control arms and McPherson struts.

[iNVision]

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.



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



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.



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.



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...



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.

[jlrussell4]

Nick,

Great start! I love the build sequence pictures and text. I'd like to see how you got such nice looking panels. Would it be possible to see some pictures of of the processes you used to shape some of these panels?

[godspeed]

I'm keeping an eye on this one to see how it turns out.

[iNVision]

Originally Posted by jlrussell4

Nick,

Great start! I love the build sequence pictures and text. I'd like to see how you got such nice looking panels. Would it be possible to see some pictures of of the processes you used to shape some of these panels?

Thanks for your thumbs up Mr. J. You're right about posting additional process photos....the thing is taking them...sometimes we get so involved in fabricating a part that we forget until the pieces have been completed.

Will try to remember going forward..

Cheers