1970 Lotus Europa Front Suspension Redesign ME 462 Capstone Design Spring 2007 Sponsor: Bishop Steering Technology Kel Tiedman, Jason Wou Tom Filipucci Frank Faulkenberg Brian Schludecker David Giles Team Members May 3, 2007

Project Background 1970 Lotus Europa 1470cc, 4-cylinder engine producing 78 hp 120 mph top speed 13-inch wheels 2-piece control arms Stamped & welded Bolt-on ball joints Coil-over shock & spring arrangement

Customer Requirements Maintain suspension geometry Provide stable 200 mph ride Maintain 5 inch ride height Utilize 15 inch Audi wheels Utilize current frame mounting points Maintain wheel-to-wheel dimension Attempt to utilize stock shock and spring size Minimal bodywork modifications

Engineering Targets Engineering RequirementsTargetUnits Scrub Radius10mm Roll Center Height50-100mm Car Ride Height5in Anti-Dive25% Steering Axis Inclination7deg Caster Angle4deg Camber Angle-0.5deg Caster Trail15-35mm

Final Design

Upper Arm = 5.60 in Lower Arm = in Scrub = 10 mm Steering Axis = 16.5º Rotor Clearance = 0.69 in

Design Animation

Design Evaluation Suspension Analysis Four-bar Mechanism

Design Evaluation “Fourbar” Program – Norton Evaluate each control arm length iteration Rough wheel motion “Four-bar Mechanism” - Matlab Quantitative wheel motion ProEngineer Mechanism output to Excel “Camber Curve” - Matlab Camber curve comparison

Design Evaluation Iteration Method 2 Iteration Sets First Set – 11 possibilities Manipulated Variables Scrub radius Steering axis Second Set – 6 possibilities Same Variables Smaller scrub radii Larger steering axes

Design Evaluation Case 5: Steering Axis – 16.5° Scrub radius – 10.0 mm Upper arm – 5.60 in Lower arm – in Case 1: Steering Axis – 16.0° Scrub radius – 11.0 mm Upper arm – 5.70 in Lower arm – in

Design Evaluation

FEA Results

Final Evaluation Engineering RequirementsTargetResultGoal Met Scrub Radius10 mm Roll Center Height mm50.8 mm Car Ride Height5 in Anti-Dive25% Steering Axis Inclination7º16.5º Caster Angle4º12º Camber Angle-0.5º Caster Trail15-35 mm25 mm

Conclusion & Recommendations Conclusion Kinematic motion requirements met Verified some physical packaging requirements Recommendations Further finalization of arm shapes In-depth finite element analysis Close examination of control arms and knuckle attachment One team for knuckle/brake and suspension design

Questions?