I've been noodling building something like a D-Sport and I'm wondering what donor candidates might be available cheap. What small, light sports cars might have double A-arm suspension front with IRS rear and is both common and cheap? Triumph Spitfire?
The answer always is "Miata".
What he said ^
Triumph Spitfire has been used on a variety of race and specialty builders (think Lotus) but not the rear suspension, which was always it's Achilles heel. For what you are describing, our standard answer to everything is your best choice (Miata).
stroker said:Triumph Spitfire?
My Triumph Spitfire mostly has a Miata suspension under is.
You could be a contrarian and noodle up the suspension gibblets from a Suzuki Capuchino. Fits under an MG Midget
RX-8?
C4
RX8
I will mention the gen1 RAV4 has 5-4.5 wheels and 12 inch brakes, 4wd has a lightweight irs diff, but struts front
And just to really add a non-orthodox suggestion, the gen2 ford explorer is a a-arm front suspension, the gen3 has irs.
btw, here is the RX8 front suspension I pulled from the $200 RX8.
In reply to stroker :
The Zoomboni not only uses Miata suspension front and rear, but the whole subframes just to keep everything simple. This wheel works, no need to reinvent it.
KyAllroad (Jeremy) said:In reply to stroker :
The Zoomboni not only uses Miata suspension front and rear, but the whole subframes just to keep everything simple. This wheel works, no need to reinvent it.
It seemed strange to even see the question when the answer is, once again, the answer.
The links and wishbones are the easiest to DIY fab, welded steel tubes with appropriate joints on the ends.
The Vertical Links, especially for driven wheels, are the most difficult to DIY, castings, forgings, or weldments, and difficult to design parts that are strong, light, and robust, so take advantage of the OEM investment in R&D and re-purpose something.
Select the VL that meet your needs, by strength, weight, # of lugs and PCD, wheel sizes available.
Lay out the suspension geometry based on the VL joints, which gives you the chassis mounting points, and then design the chassis
to handle the loads and stiffness requirements (find a copy of 'Racing and Sports Car Chassis Design' by Costin and Phipps).
Welded steel space frames are the most practical for DIY, both in design and fabrication. Triangulation and mechanical engineering knowledge to calculate the stresses in each tube member of the truss, selection of the tubes size and wall thickness, and design of the welded joints. Helps to have metalworking and welding skills.
But monocoque and similar stressed skin structures are possible (find a copy of 'Aircraft Structures' by David Peery). The skin stresses of a torque box are somewhat simple; t=2qA where t= max torque stress, q = skin shear strength, A= enclosed box area. But the devil lies in the details of skin reinforcement to prevent buckling, corner and seam joints, torque box intersections, and fastener placement and fabrication. Helps to have some airframe construction/maintenance experience, and sheet metal tools & skills.
Composite chassis, carbon fiber/fiberglass is a different ballgame, both design and fabrication. There is plenty of knowledge out there now that you can take advantage of. Burt Rutan offers a lot of practical advice for kit plane constructors that can be used by anyone building a composite structure.
So good luck, and have fun.
Carter
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