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Suspension Geometry                               

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WinGeo3 5.01 - Suspension Geometry with Force-Based Roll Centers

The latest version 5.01 of the WinGeo3 suspension geometry program includes the Expert suite of programs. This version includes the Parts menu which permits uprights and a-arms to be measured off the car in their own coordinate system and then assembled into a suspension. This is more accurate than trying to measure the center of a rotation of a ball joint. This reflects the way stock car teams build suspensions.

The Expert suite of programs includes the SetupAarm and SetupRear programs which permit the analysis of camber shims, caster slugs and anti-dive slugs. This simple program produces a camber curve allowing the race engineer to achieve a desired camber angle at a specific ride and roll target.

WinGeo analyses automotive suspensions. The program will determine how camber, toe, scrub, roll center, etc., change as the vehicle moves through different combinations of ride height, body roll, or steering inputs. The user can also change the alignment (by shims or other adjustment) and see the effect on camber, caster and bumpsteer.

The program allows the user to rapidly and accurately study a suspension design or setting. The user may move the chassis using the keyboard arrows and quickly see the consequences on the screen. The program displays the computed suspension parameters on the screen as well as a graphical view of the vehicle. The program also shows how the parameter is determined.

The WinGeo3 5.01 Geometry program now comes in three versions:

Advanced $495 -  Full three-dimensional kinematic analysis of Double A-Arm and MacPherson Strut suspensions. Analyze up to five different suspensions. The user can move the chassis to a particular point or run through a range of motion.  A ride iteration would compute suspension parameters for a variety of ride heights. This would produce a graph of bump steer. A roll iteration would produce a graph of roll center movement as a function of chassis roll. A steering iteration would produce a plot of net steer and Ackerman at different steering inputs.

The program will compute the suspension values for a given set of ride, roll, steer and pitch. The user may also enter spring or shock displacement and calculate the chassis position that produces those values. This is useful if you have data on suspension travel. The user may also specify chassis clearance. This is useful for studying the effect of setup changes. For instance, you might measure the car on a flat plate. But when the car goes to pit lane the team will record chassis clearance values. These can be entered into the program to calculate the corresponding chassis ride and roll values.

 In addition to Double A-arm and MacPherson Strut suspension you can also analyze solid rear-axle suspensions with a Panhard rod and five-link independent suspensions (often called Multi-Link).

 The Fixture allows the user to measure the points of the hub on a measuring device and then attach the hub in a specific position by specifying camber, toesteer, caster and track. This is an essential tool for stock car teams.

The Build menu allows the user to manipulate existing parts by changing tire size, track or other parameters. The Design menu allows the user to create a suspension from desired suspension parameters. The user may specify caster and kingpin and Instant Center location and the program will design a suspension with those characteristics.

The Table feature permits the user to run the suspension through a range of motion and produce a table of suspension values. The range of motion might be ride height and the table would show bump steer. Or it might be the path a car takes through a turn so you can study suspension movement through the turn.

The Solve for Steering permits the user to specify a steer value and calculate the steering input that produces that steering value.

This version will also handle third springs and five-link independent suspensions.

Expert $895 - This version was introduced in November, 2008. This is the Advanced version plus the Parts menu which permits the user to assemble a suspension from parts and to adjust that suspension accurately.

Regular This version was previously available for $345. But most of the few customers who purchased in this 2005 upgraded to the Advanced version within one month. The Advanced version offers many more features and is a better buy.

Premier/Data or Grand Prix / Data $1,895 Load data and compute suspension for any point on the track. The data may be in a MATLAB file, an ASCII comma-separated variable or blank-separated variable and must include speed, lateral G, steering and suspension travel.

Tire Deflection Specify a vertical tire deflection rate for the tire (spring rate) and the program will compute a tire deflection proportional to the load from the springs and swaybars. With many modern cars having 50% of their suspension travel in the tires, this analytical tool is vital for proper analysis. There is also a special report for understanding the effect of different tire spring rates.

Fundamental Analysis Compute camber and scrub movement from instant center location.
Derivative Analysis Compute Instant Center locations from camber and scrub calculations.
Rising Rate Compute rising rate values for spring displacements.
Anti-Dive, Anti-Squat, Sideview Swingarm additional analysis of anti- properties.
Pitch Center
Halfshaft Analysis

Suspension Parameters

This plot shows a race car from the rear looking towards the front. This is the driver's view of the front suspension. The car is turning left; has rolled one degree and moved 0.5 inches below pit lane ride height. The right tire has 0.439 degrees of camber and the left tire -0.964 degrees.The right spring has compressed 0.613 inches and the right shock 0.531 inches.The antiroll bar has twisted 5.071 degrees. The right tire has toesteer of 0.021 degrees to the left and the left tire has zero toesteer. The right side instant center is 2.919 inches above ground and the left is 5.112 inches. The roll center has moved 5.980 inches to the left of the centerline and is 1.136 inches above ground.



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