Chassis Design Details
Chassis Structure (Cont.)
Figures 8 and 9 are camber charts which show camber change through a typical range of suspension movement under normal operating conditions.
As can be seen from the above charts, the front camber change is greater than the rear in all instances. This variation is required due to dynamic chassis loads, one of which is lateral weight transfer. As the actual corner weights in a 1.3G (0 longitudinal acc.) corner are nearly 1080 lbs (outside front), 860 lbs (outside rear), 100 lbs (front inside), and 215 lbs. (rear inside) with body roll of 1 degree, the greater negative camber gain in the front suspension is required to maximize tire contact patch and to deal with the large slip angles imposed. It is therefore also important that the inside tires have a positive camber gain to maintain a vertical contact patch. In the case of the rear camber gain, less is required to meet these cornering loads and under straight line acceleration low camber gain is required to maintain as flat a tire contact patch as is possible when the rear squats due to longitudinal weight transfer. The above curves produce the proper camber angles to take advantage of the current high performance radial tire design specifications.
The front and rear suspensions are completely adjustable for various static camber and caster angles. Depending on the circuit type, tire configuration, and driver preference, these angles may differ considerably from the settings as shown above. For instance, if the circuit is a low speed type with many slow corners, the driver may elect to increase front camber and castor to allow the vehicle to point into the corner quicker. Also, this type of circuit will often require less anti-squat in the rear to allow more bite exiting a corner. This would require changing the rear castor settings to allow more rearward weight transfer. High speed circuit settings typically will be set so that the vehicle will react to driver inputs in a very gentle manner with a leaning toward understeer and stability. The adjustability of this chassis will allow adaptability to virtually any circuit or driver preference.
Figure 10 below show the cockpit adjustment plate. This unit is mounted just in front of the gearlever on the center tunnel.
Anti-Roll Bars (cockpit adjustable-blade type)
Unlike the static changes that the driver can make to the chassis settings while in the garage or pits, operation of the anti-roll bar adjusters is done while in motion. This adjustment allows the driver to change and fine tune the chassis balance characteristics (IE. understeer/neutral/oversteer) to suit the road and track conditions at any given time.
If, for instance, the driver wishes the vehicle to understeer(push) a bit during high speed cornering, they would move the FRONT lever towards "FIRM" a notch to increase the roll stiffness and therein produce the effect. Conversely, the driver could elect to reduce the rear roll stiffness by moving the REAR lever towards "SOFT" and produce a similar effect.
Ideally, once set to driver preference for a given circuit or road condition, these adjustments will remain unchanged unless conditions change. (IE. The road surface becomes wet or oily.) In the instance of the above conditions, the driver would reduce the settings towards "SOFT" to allow greater lateral weight transfer to match the road conditions and driver preference.
Figures 11 and 12 below illustrates front anti-roll bar in both full soft and full firm positions.
Figure 11 Full Soft Position
Figure 12 Full Firm Position
Cockpit Adjustable Brake Bias
The brake bias (front to rear balance) is adjustable by a dash mounted knob (Figure 13) which is turned either clockwise or counterclockwise to vary front and rear brake line pressures.
Figure 13 - Brake Bias Adj.
The brakes and master cylinders on this chassis are sized to give a neutral bias when the adjustment is in the center position. (IE. all four corners will lock at the same time.) As the loading in the vehicle changes due to passenger or fuel load changes the driver can fine tune the balance to maintain this bias under all conditions.
Also, many drivers wish to have a slight rearward bias, which would allow the rear brakes to lock first. This setting is quite useful on high speed circuits which have some very slow corners. With the chassis set for high speed understeer, it if often difficult to point the nose in at slow speed, therefore a rearward brake bias allows the driver to momentarily lock the rear brakes and tighten the arc into the corner.
Figure 14 shows the chassis assembly with suspension and engine systems in place.
Brakes & Pedal Assembly
The Front brakes are Wilwood Superlite IIA NASCAR Type with 12.19 X 1.38 H/D curved fin rotors. The rear are Wilwood Dynalite II, with 12.19X1.25 H/D curved fin rotors. Pads are Wilwood polymatrix units. The pedal assembly is a Wilwood alloy 2 pedal unit with bias adjustment.
Carbon pads are used for competition usage. There are optional composite center fed ducts on the front brakes which lead from the forward brake ducts for cooling of the vented rotor. The pedal assembly is a Tilton adjustable dual unit with inclusion of a hydraulic clutch system.
Figure 15 - Standard Rear Brake Assy
The standard fuel tank is a 16 gallon fuel cell (figure 16). This cell is a foam filled polyethylene unit with a 2.5 inch diameter filler opening with a rollover flap to prevent fuel spill. The cell has AN fittings for: fuel pickup, fuel return, and vent. ( The vent also has a ball valve for rollover protection.) It also contains a standard fuel level sender.
Figure 16 - Fuel Cell
The standard Bodywork is fabricated utilizing ISO resins, E-Glass cloth, mat, and core mat, with optional KEVLAR reinforcement in side door area. All layup is done by hand. The body is permanently mounted to the chassis utilizing structural urethane adhesives and mechanical fasteners.