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 Requirements Target Units

Scrub Radius 10 mm

Roll Center Height 50-100 mm

Car Ride Height 5 in

Anti-Dive 25 %

Steering Axis Inclination 7 deg

Caster Angle 4 deg

Camber Angle -0.5 deg

Caster Trail 15-35 mm

Final Design

Final Design

Upper Arm = 5.60 in Lower Arm = 11.03 in Scrub = 10 mm Steering Axis = 16.5º Rotor Clearance = 0.69 in

Design Animation

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 Method2 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 – 11.03 in

Case 1: Steering Axis – 16.0° Scrub radius – 11.0 mm Upper arm – 5.70 in Lower arm – 11.04 in

Design Evaluation

Design Evaluation

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2

Degree

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lCamber Curve Comparsion

Case 5

Case 1Zero scrub/ 20 Degree steering axis

35 mm scrub/ 7 Degree steering axis

FEA Results

Final Evaluation

Engineering Requirements Target Result Goal Met

Scrub Radius 10 mm 10 mm  

Roll Center Height 50-100 mm 50.8 mm  

Car Ride Height 5 in 5 in  

Anti-Dive 25% 25%  

Steering Axis Inclination 7º 16.5º  

Caster Angle 4º 12º  

Camber Angle -0.5º -0.5º  

Caster Trail 15-35 mm 25 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?