The Basics Of Rear Suspension - Tech

ConclusionSo, what have we learned here? The main thing to take away from this rear suspension discussion is that there's more to improving traction than just dumping 50 pounds of ballast in the trunk. You can use specific suspension components to help you create optimal traction, but only if you understand how all these components work. This has been a primer intended to introduce you to the ideas around rear suspension science. There are dozens of other variables like weight distribution, engine torque, shock tuning, tire pressures, and of dozens more that contribute to improving traction. That's why this is as much art as it is science. But when you get it to work for you, your car will make you out to be a low-e.t. hero.

SimulationsThere are several computer simulations that do a great job of implementing the ideas around four-link rear suspensions. It might be useful to hit both of these Web site to investigate the information these simulations can deliver. The first is Performance Trends' 4 Link Calculator ($80). An interesting visual cue for this program is a side view of a drag-race doorslammer equipped with a four-link rear suspension. The illustration helps you understand how the instant center moves in dynamic situations and how the dynamics affect the car during the launch. Performance Trends even offers a limited but free downloadable version of the program you can use to experience it first hand.

The second program is by Racing Systems Analysis. FourLink ($169) produces a chart output that shows shock-absorber separation, force acting on the shocks, and rear tire load, along with average tire force and tire force variation in percentage during the first 60 feet. These outputs are great, because you're looking to produce the highest average tire force in pounds along with the least amount of variation in tire force applied to the pavement. One misconception is that once the force is applied to the rear tires, it is consistent throughout the entire run. The reality is that due to dynamic changes as the car accelerates, the IC moves, and this constantly changes the force applied to the rear tires loading and unloading. The idea is to minimize these force variations, making the car more predictable and stable as it runs down the track.