3-types of suspension:
Vehicles modified at our shop have springs that fall into three different categories: leaf, coil and torsion bar. For coil and leaf springs, the general rule is that the taller the spring is, the stiffer it is. On most coil and leaf spring equipped rigs, ride firmness will remain close to stock on lifts up to 4". From there up, ride becomes increasingly firm. On vehicles with torsion bars our suspension lift alone does not noticeably change ride quality because the torsion bars are not replaced. Firming-up the ride isn't always a bad thing; some factory suspensions are too soft.
These factors greatly impact ride quality:
1- On leaf springs suspensions, your choice of Superlift Heavy-Duty or Superide leafs.
2- Using multi-shock kits and add-a-leafs will firm-up the ride.
3- Tire type and their operating air pressure... Larger diameter tires normally have more sidewall flex which softens the ride and increases body roll. Conversely, a bias-ply tire (non-radial) run at maximum air pressure will stiffen ride quality.
These factors influence ride quality, plus they affect how much net suspension lift is attained:
1- What factory suspension package the vehicle has, and it's condition.
2- Adding additional weight, such as a winch, bumpers, storage boxes, extra fuel capacity, etc..
3- Track width is is the distance from outside of tire-to-outside of tire.
The Math: On all torsion bar IFS vehicles and Ford's TTB vehicles, the leverage exerted on the springs increases as track width increases; the wider tires / wheels make longer levers. This added leverage brings ride height down slightly. If really wide tires/wheels are used, or the vehicle is exceptionally heavy, the vehicle may set too low and/or the ride may be too "spongy". In some cases heavier rated torsion bars may be needed in order to reach maximum lift height. Heavier torsion bars are available from your local 4x4 shop or new car dealership parts department.
On coil spring equipped TTB vehicles, these leverage and weight related problems are addressed by using slightly heavier rated coils and / or shims that install under the coils.
