1. Team UDFSAE: Suspension Group
David Zipf, Doug Corley, Josh Akell
Faculty Advisor: Dr. Steve Timmins
Sponsor: Jamie Gil Master Machinist: Steve Beard, Jeff Rickets
Project Scope
To design and fabricate all suspension components, including the front and rear A-arms, uprights, front hubs, mounting points, push rods and rockers, tie rods, spring and shock locations, control arm clevises, sway bar system and steering rods. Suspension must conform to FSAE rules and have wide range of adjustability
Problem Background
Formula SAE® is a student design competition organized by SAE International (formerly Society of Automotive Engineers).
Concept is that a fictional manufacturing company has contracted a design team to develop a small Formula-style race car.
Target marketing group for the race car is the non-professional weekend autocross racer.
Student team designs, builds and tests a prototype based on a series of rules to ensure safe operation and clever problem solving.
Glossary of Terms
Front Suspension
Rear Suspension
Design Detail
Evaluated and optimized using kinematic and force analysis.
Measures of performance include bump steer and roll center movement.
Designed to undergo forces seen in a combination of hitting a bump, braking, and cornering (5G vertical and 5G towards center of car, simulates extreme combined bump and corner loads).
Adjustability in the wheel rate and spring rate was critical and can be adjusted by changing the sway bars’ pickup points.
FBD of forces in suspension FEA of rocker Sketch of steering arms
Mounting
Upright Clevis
Changed from steel to aluminum mounts, halved weight. Rear includes integrated toe link mount
Chassis Clevis
Bolted on steel. Shims allow
alignment changes without removal
of wheel. Camber, caster, and KPA
can be adjusted this way
Pushrods
Made from welded steel. Designed to withstand combined 5G bump impact and cornering load
Front Pushrod Mount Rear Pushrod Mount
Key Metrics and Targets
Metric
Target Value
Wheel Base
60”
Spring Rate
~ 350 lbs./in (adjustable)
Track Width
50” (front/rear)
Dynamic Wheel Travel
2.0”
Minimum Turning Circle
⌀ 20 feet
Camber
-1.5° (static), minimal gain
Ease of Camber/Toe Adjustment
Adjustment w/o removal of wheel/hub
Scrub Radius
0.5”
Roll Center
High as possible without causing jacking.
Bump Steer
≤ 1/16”/inch vertical deflection
Cost
< $1000
Caster Angle 4°
Ride Height
2.5” from lowest point of car
System Weight
<30 lbs/corner with wheel & tire