One area of race car performance that still seems difficult to explain is suspension and handling. Although many enthusiasts can t ell you what changes will produce what results, they may not be able to tell you why these changes produce these results. Since not all enthusiasts have an engineering or physics background , this book will attempt to discuss suspensions and handling in terms the layperson can understand. Good handling could be described as going around corners faster while improving driver control. Just as in the case of engine tuning, where very small changes can have a dramatic effect on horsepower output, very slight changes in the suspension of your car can have significant effects on your handling. Even a one-degree change in camber can have a measurable effect on performance, so a high degree of precision is required to set-up a suspension properly.
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This is where the "Big picture" provided by Chassis Engineering comes in. While not as detailed as some of the design books I have seen, Chassis Engineering excels because of the methodical explanations and progression through the key elements that affect handling—weight distribution, suspension, chassis and aerodynamics. It provides formulas, diagrams and photos to help the reader understand each concept it discusses. I found that when I had finished reading it, I could conceptualize a race car design beyond my earlier fanciful drawings.
I could see the "big picture" of vehicle dynamics--weight, its transfer, grip, suspension geometry and components. I could understand the interaction between chassis , aerodynamics, and suspension. More anti-squat is a good solution to this problem. Photo by Michael Lutfy.
I delved deeper into the topics covered in " Chassis Engineering" by purchasing specialty books, but whenever I needed a reminder of how a car behaves, I would open my trusty copy of this book. The book is laid out in a format that is easy to follow. The essentials of vehicle handling are discussed first, which gives the reader a clear understanding of how weight distribution and transfer affects handling.
Successive chapters introduce the actual components of the suspension and suspension design as well as frame design and construction. One of the most novel parts of this book is the demonstration of using balsa wood to make frame designs and then testing them for torsional rigidity. I have personally spent many hours cutting, gluing and testing! The great part about this method is that at the correct scale, it actually correlates to steel tubing and can form the basis of your own model.
Book Sections The book begins with a discussion about tires, their performance characteristics and skipad testing. Bushings The bushings section looks at the various types of bushings steel, nylon, urethane, spherical bearing used in suspensions and their pros and cons.
It also looks at the effects of deflection steer and camber loss caused by different types of bushings. Topics including spring rates, wheel rates, spring selection, mounting locations, and ride height adjustment are discussed. Shock absorber dampening attributes and mounting are also discussed. The book does step into a bit of fabrication at this point too, with a how-to on coil spring cutting and lengths.
Front Suspension Design After laying down the essential foundations of handling, the author moves on to front suspension design. The author discusses the geometry of an unequal length wishbone suspension, and uses this type as the basis for demonstrating aspects such as swing arm length, camber gain, roll center movement and bump steer. Even though it is not a detailed design of a suspension, the principles are well explained and that is what I found most valuable.
For actually playing with suspension designs, the author points to computer software, which makes a lot of sense. If you understand the principles, the computer software does the intense calculations.
Double A-arms are preferred, because they mount the wheel and hub on rigid arms, which do not deflect during hard cornering. The problem of equal length arms is that they do not provide any camber gain.
There is no right or wrong answer. Figure Unequal length control arms mounted at various angles can provide a variety of roll center heights and swing-arm lengths. Live Axle Rear Suspension Design In this section, the author moves to the rear of the car, where live axle rear suspension design is discussed.
He describes design requirements such as lateral control, roll center height, bump steer, and anti-squat for the various types of live axle suspension. There are some good diagrams in this section which help to differentiate between the different linkage types, and which demonstrate the geometry. Independent Rear Suspension IRS Like the live axle section, this one looks at the characteristics of the suspension and talks about the design requirements for such suspensions.
Various types including corvette, formula and Jaguar IRS are covered. From "Chassis Engineering" by Herb Adams, showing how the circle of traction works to divide traction between different accelerations.
Building Rear Suspensions This chapter provides brief but useful advice on various aspects of constructing the rear suspension. Both live axle and IRS are discussed. Topics such as live axle lateral location, links, camber and IRS rear suspension components are covered. Frame Design One of my favourite chapters in this book, Frame Design covers the basics of structural design using balsa wood stick representing tubes and balsa sheet representing sheer panels models.
The examples beg to be tried on your own and give an excellent opportunity to model your chassis and car in small scale. The author also discusses different types of frames Ladder, backbone, and their features as well as frame layout. Building the Frame This section looks very briefly at the construction of a tube frame for a short track oval race car.
There is some practical advice, but it very minimal and it is not a guide to fabrication. It might be better called "Frame building and testing tips" Aerodynamic Downforce This section provides some very basic aero theory for the reader and then proceeds into several practical examples of using the aerodynamics of the car in various types of racing.
There are some good illustrations and photos to help the reader understand the use of air flows, aero devices, downforce generation and the use of air flow for cooling. In all, it provides a good practical overview of aerodynamics that adds to the learnings from the previous chapters. Rotating Inertia The rotating masses of the driveline and running gear are discussed in this section. The author discusses the goal of reducing these masses to improve acceleration and ultimately top speed in a race car.
Tuning Techniques Tuning the final product is given a fair bit of treatment in this book. The section begins with instructions on aligning the front and rear wheels to obtain good results from tuning.
Then it moves on to the process of testing using a G-Force logger and test procedures. The book discusses the results and recommends adjustments to the car depending on the logger outputs. Helpfulness to amateur race car designers This book is a broad introduction to race car design and an ongoing reference for the designer.
It methodically builds the key knowledge a person needs about race car design. From handling, to design and construction, to testing, it gives the reader an overall perspective of how race cars are put together and how each component affects the others.
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