T E C H N O L O G Y
These book reviews will appear in Racecar Engineering magazine. I included them in the October issue of TV MOTORSPORTS.
About a year ago the Society of Automotive Engineers (SAE) announced the publication of The Shock Absorber Handbook by John Dixon. I was interested because Im working on a shock book myself. I suspected it would be an academic-style work as was Dixons book on vehicle dynamics. I didnt order it right away but began to get emails and phone calls from people who had. They were unanimously disappointed in the book. Hurry up and finish your book, was what people told me.
When I finally got the book I experienced the same disappointment. This is academic writing at its worstendless equations with no meaningful explanation. I hated this when I was in engineering school and I hate it now. No wonder young people dont enter engineering schools. College instructors know all the equations but few have any practical knowledge.
Seeing a book with the title Shock Absorber Handbook and a photo of a racing car suspension on the cover naturally gets the juices flowing. Unfortunately, there is little sustenance in these pages. The introduction chapter contains an interesting history of dampers and a useful review of the literature. Automotive engineers and designers might appreciate an all-in-one reference source containing mathematical material covering vibration theory, ride and handling, fluid mechanics, and damper basics; but this work is not useful to the working race engineer or club racer.
Written by John C. Dixon, 495 pages, ISBN 0-7680-0050-5, published in 1999 by Society of Automotive Engineers. $49.
Book Review: Inside: The TT44 Manual
In contrast to the book just reviewed, this simple little manual has plenty of practical info for the club racer, racecar engineer, or motor racing enthusiast. Profusely illustrated with drawings, black and white photos, and graphs the manual begins with a precise description of hydraulic flow inside the TT44.
The four external adjustmentslow-speed compression, low-speed rebound, reservoir compression, and high-speed compressionare fully explained with photos and damping force vs. shaft speed graphs. Internal adjustments, seemingly infinite variations of shim stacks and preload shims, get a complete mechanical description backed up by chapters on shim-stack theory, hysteresis, and combining main piston and reservoir damping.
Chapter 9: Damping Functions provides some advice on how to deal with the compromises necessary to optimize a racecar. The discussion includes aerodynamic and mechanical grip, tire management, and driver comfort and control. There is also a discussion of different types of ground-effects cars and the relationship between compression and rebound damping. Chapters 10 and 11 present Öhlins recommended damper configurations and damping guidelines.
The first 11 chapters in this manual, 26 pages, represent the most practical information yet presented about racing shock absorbers. Having said that, a club racer expecting to learn how many clicks of rebound will cure his racecars entry understeer in Turn 4 of his home course will be disappointed. Tire variations as well as differences in driver style and skill preclude that level of detail.
Chapter 12 is an illustrated guide to disassembly, adjustment, and repair of the TT44. The next chapter offers force vs. shaft speed graphs for the full range of each adjusterpresented in pounds and inches/second to our delight and astonishment. The last three chapters present dimensioned engineering drawings for standard and optional parts.
Written and published in 1999 by Öhlins Racing AB, Sweden. 63 pages. Send a check for $30 ($25 plus $5 for shipping and handling) to Motorsports Spares at 101N Gasoline Alley, Indianapolis, IN 46222.
Ill publish my own shock book the middle of next year. It will include chapters on tires and basic vehicle dynamics as well as shock basics and a review of available racing dampers. There will be some equations.
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