Chassis Design

Chassis layout

The 289FIA chassis integrates body mounting right into the main structure.  The doors hinge and latch right onto the chassis, preventing sag and misalignment.  Mounting brackets for the front and rear jack-pads (or bumpers, if you prefer) are built in.  Like the original 289, the 19 gallon fuel tank is carried above the rear suspension.

A tubular steel sub-structure is welded directly to the main rails and extends completely around the passenger compartment. This structure provides not only the mounting areas for the body support panels, door hinges, latches and dashboard, but also some passenger protection.

Some companies use round tubes for the main chassis rails.  As you can see above, we use rectangular (4" x 3" x 1/8" wall) steel.

Loads are fed uniformly through the chassis rails:  There are no notches or variations in rail size between the major front and rear loads into the chassis from the suspension and engine.  This means that the rails act in the most efficient manner, and there are no high-stress areas to initiate a structural failure.

Our powder-coating option will make the chassis rust free and attractive for many years too.

For the rest of our design logic, check out our detailed engineering comparison
between possible round tube, space frame and monocoque Cobra chassis.

Because the inner panels of body rivet and bond to the chassis, we have created a semi-unitized structure that extends from the front of the engine compartment through the rocker panels and along the rear of the passenger compartment. Assembling the car with this degree of integration may take a little longer, but you end up with a much stiffer overall structure.   Our bare chassis has been measured at approximately 3200 lbft/deg.  The body and inner panels will add at least an additional 300 lbft/deg.  Not bad for an open car!

Our suspension pickup points feed loads directly into the chassis, minimizing bending moments. Where there are practical limitations, large sections and/or reinforcements are designed in.  The chassis allows the suspension to take full advantage of today's advanced tire technology.

Our optional roll bar is actually functional, bolting directly to the main chassis rails.  Kind of nice, considering some other replicas' bars are there just for show!  While we're on the safety stuff, note that all the seat belt and shoulder harness mounting points (with threaded inserts) are designed into the chassis.   

And a little Crash Protection: Our chassis has three stages of impact dissipation.

  • The bumpers will collapse progressively until the bracket contacts the front of bumperette.
  • When the front bumpers are hit hard enough, the chassis is designed to have controlled shear where the bumper brackets are attached.
  • The kickups in the front section of the chassis are designed to distort progressively up and back under severe impact.

Frankly, the doors, while steel lined, don't offer much side impact protection.  The original latches are just not strong enough for us to justify such a claim.  Our construction is just designed to keep the doors from sagging.

Back to the 289 Home Page!!

Bare chassis

fia/chassis.htm  1-25-2001