Maximizing Suspension Performance - CHP How It Works

Maximizing Suspension Performance Requires Scaling and Setting Crossweights. Industry Experts Tell You How

Stephen Kim Apr 22, 2011 0 Comment(s)
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John Hotchkis: A very undesirable characteristic in any car that’s driven on the street or around a road course is a chassis that understeers or oversteers more turning in one direction than the other. The best way to get a car to turn left and right equally is by making sure weight on the tires is as equal as possible. Electronic scales are great tuning tools because they enable adjusting crossweights. If you were to take the corner weight at one side of a car, add it to the weight at its diagonally opposite corner of the car, then divide that total by the total weight of the car, you’d get the crossweight percentage. Ideally, the percentage should be as close to 50 percent as you can get it. This ensures that each corner of the car sees equal loads in corners and eliminates weight jacking so you don’t have more weight on the tires when turning in one direction versus the other.

Adjustment Methods

Matt Jones: One of the great perks of an aftermarket coilover system is the ease in which it can be adjusted. When it comes to setting corner weights, this can easily be accomplished by lowering or raising the spring perch on the shock body. Ride height and corner weight adjustment on cars with OE-style coil springs is a bit more difficult. In these types of applications, you can actually rotate the spring in the lower spring pocket and install stop bolts to keep it in place. Some circle track parts suppliers even offer threaded adjusters to make wedge adjustments easy. Typically, these methods will not be as simple as a coilover for ease of access, but the adjustment methods are the same.

Doug Norrdin: When setting the corner weights and crossweights of a car, aftermarket coilover systems greatly simplify the process. However, adjusting corner weights aren’t that difficult with factory-style coil springs, either. Any coil spring can be clocked, or rotated within the spring pocket to change the weight at that corner. Likewise, spacers can be wedged between the spring and the control arm or frame. Leaf springs are tough to tune, since the only way to adjust the corner weight with them is to change the shackle length. Unfortunately, that’s not always a great idea. Generally, if you raise the right rear corner of a car, it will increase weight on the right rear and the left front corners of the car. Conversely, raising the left rear corner of a car will increase weight on the left rear and right front. Lowering one corner of a car has the opposite effect and reduces weight over that corner and its diagonally opposite corner. In most scenarios, it’s best to balance out a car by moving around the mass within the car first before corner weighting. As a last resort, you can use the endlinks of a sway bar to preload and weight jack the chassis.

John Hotchkis: Increasing the ride height at one corner of the car has the effect of putting more weight on that corner. Conversely, lowering one corner of a car reduces weight at that corner. Adjusting corner weights without the luxury of aftermarket coilovers can be time consuming, but it can be done. You can shim springs or even trim the coils slightly to get the corner weight you want. Some aftermarket control arms have provisions for shims of various thicknesses in the spring buckets. Oftentimes, we’ll just work on optimizing corner weights on the front. If we can get the front where we want them, it’s usually good enough and the car will handle great on the track.

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