By this point in time I was ta
By this point in time I was taking the car to road race tracks and starting to learn about vehicular dynamics. I had noticed that the rear end felt soft with respect to other cars I had driven in anger, but that the shocks were absolutely perfect for the amount of spring in both the front and rear of the car.
So, I got out the old reference manuals on high performance driving, and suspension setups that I rad read (oh so) many years ago. I have all of the Carrol Smith books on race car preperation, setup, tuning,..., Race Car engineering and Mechanics by vanValkenburg,and just to be sure I picked up a copy of Race Car Vehicular Dynamics by Milliken and Milliken, and a copy of Race Car Aerodymanics, Designing for speed by Katz. I recommend that each person who really wants to understand suspension stuff, get these (kind of) books, read them and attempt to understand them.
Due to the use at the race tracks, my rear tires were showing cord, so I odered up a set of the same tires in the same size as was on the car, had them mounted and balanced hopint an invisible tire defect was interacting with the suspension alignments in some unknown way.
Result: My car was even worse than before! I first noticed how much worse at MSR in Cresson while driving through Big Bend with the steering wheel more than 15 degrees in the opposite direction as the arc the car was driving. No wonder the car felt no nervous when I shifted up to the next higher gear, the rear end had to step back in a whole foot when the power came off!
Something had to be done! I went to an old mechanic and expained the problem to him, one of this shop mechanics had worked on the Jaguar race team while Jaguar was running the LeMans Spice car (that lovely V12 in the GTP white body circa 1990). He indicated that they had all sorts of high speed instability issues with that car until they got the front end at the correct ride height.
This piqued my curiosity, so I went back to my books and looked up suspension setup. In each and every book there was a similar sentance:: The first step in setting up a suspension was to set the ride heights and then work from there.
OK, but what ride heights would be appropriate? I had no idea.
I talked with several other people who use/operate high performance cars, and ask them for guidance. One of them pointed me to David Moore at MooreSpeed a race car preperation facillity and Porsche mechanic. I took my car to David, explained the situation; and we agreed to do a complete grounds up suspension setup to factory specs. This included setting the ride heights, adjusting all the normal stuff, and then finishing by getting the corner weights set correctly with my weight in the drivers seat.
Within 10 feet of leaving his facillity, I knew the problems were vastly better, and by the time I got home, I was considering this the best money I had ever spent on mechanics work! The car was completely transformed. It sould drive straight down the hiway, it displaied no hints of instability, or nervousness, and one could hit the brakes at unreasonable speeds with ones eyes closed (if the car was pointed straight before braking).
OK, now that the car was sorted, what did we learn, and how does this apply to other cars with double a-arm suspensions? Stay tuned!