Mk III-T Chassis

Bare Chassis, just painted

The bare chassis features a high strength driver’s cage, including front hoop and braces, main hoop, forward braces, and headrest, all fabricated of 4130 Chrome-Moly tubing, 1 3/8” diameter, .080” wall thickness, joined by “secret” fillet braze alloy. This alloy, special ordered from England, has been used for decades by race car and race bike constructors over there, just for this purpose. It allows high strength joints, with fillets that spread the load over a broader area, and that can be made without heating the 4130 to fusion temperature as welding would do. Thus we avoid creating a heat-affected zone of potential fracture. Cooper, Lotus and others used this technique in fabricating Formula One chassis, back when they were tubular frames, as well as Spondon and others in racing bike chassis. The remainder of the structure is 1” square seamless mild steel tubing, primarily joined by MIG welding. The main stiffness of the chassis is provided by the triangular-section torsion boxes which form the sidepods, with the stressed engine providing necessary strength in the rear bay. All suspension loads are fed directly into the central cage.

Chassis Frame with Floor Pan

The floor skin is 6061-T651, .062” thick, providing stiffness and intrusion protection for the driver.

Floor Pan with Full Belly Pan

The Belly pan, and all other aluminum sheet metal, is 6061-T651, chosen for strength and resistance to corrosion. The full pan is .031”, therefore there is a double layer of material in the cockpit floor.

Side Pod Ribs

Chassis side sheet is 6061, .062”; ribs are 6061, .031”.

Floor Pan and Side Pod Riveting

Structural riveting, using Monel AN-grade rivets for strength and corrosion resistance; rivets are spaced 1” O.C. approximately.

Chassis with Floor Pan and Sidepod Ribs Assembled

Sidepods are now complete until cover skins are riveted on; this must wait until fire system, fuel pump, etc. are installed and access ports added to covers.

Note rear bulkhead is now installed, it is also 6061-T651, .062”.

Fuel Cell Enclosure

Fuel cell is enclosed in 6061 sheet, .062”. Cell is ATL, 5 gal. capacity. The sheet aluminum forms the containment for the fuel cell as well as the seat back for the driver compartment.