A lift kit is an aftermarket vehicle modification that lifts either the suspension or the body to give the vehicle a higher profile. Once a kit is installed, the wheel wells ride higher, allowing taller tires to be installed. Some new 4x4 trucks and SUVs come with moderate ones already installed. There are two types: body lifts and suspension lifts. Each has its advantages and disadvantages.
The body lift kit is a 1, 2, or 3 inch (2.54, 5.08, or 7.62 cm) kit that only lifts the body from the frame. This inexpensive option consists of blocks or spacers. A body lift does not increase ground clearance; however, it might allow for slightly taller tires because it will increase the height of the wheel wells.
Depending on the model of vehicle and the height of the kit, additional money might have to be invested in raising the bumpers, extending the gearshift through the floorboard of the vehicle, and making other modifications to accommodate the body lift. Although this type causes a vehicle to sit higher, it does not alter or improve the suspension or increase travel. In general, it is therefore not considered the lift of choice by offroaders.
A suspension lift kit raises the suspension of the vehicle by replacing the front and rear leaf springs and shocks. This not only creates greater travel, it can allow for significantly taller tires, improving clearance between axles and ground. Articulation should improve with a good kit, but because the steering geometry is affected, some people choose to add steering stabilizers.
A suspension lift is more expensive than a body lift, but produces better results in terms of height, handling and ground clearance. Kits are usually 4-inch (10.16 cm) or 6-inch (15.24 cm), although there are ones as high as 18 inches (45.72 cm). Extreme lifts can drastically compromise safe handling, look odd by most standards, and are not commonly installed except on showcase or hobbyists' cars.
People who are considering a lift kit that is over 4 inches (10.16 cm) should remember that the higher they raise the vehicle's center of gravity, the less stable it will become when making sharp turns at high speeds. This can happen in a split second, such as to avoid an accident or dodge oncoming debris. The jerk of the wheel might not be a problem for stock suspension or even a 4-inch (10.16 cm) lift, but at 6 inches (15.24 cm) or higher, more caution must be used. The vehicle might also have a tendency to lean more in banked turns, such as freeway interchanges and offramps, so it is important for the driver to re-familiarize himself with the feel of the truck, SUV, or jeep after installing a lift.
If the main objective in installing a lift kit is to get tires that are at least two sizes larger than stock, it may be necessary to re-gear the car to account for the new circumference. Re-gearing will also keep the mileage as close to stock as possible. Whether or not re-gearing is needed can depend on the vehicle and tire size, so it's a good idea for car owners to talk to a professional mechanic to find out if a vehicle needs to be re-geared when the kit is installed.
Several different manufacturers make lift kits, and the prices vary, depending on the model and type. In addition to the cost of the kit, owners will need a set of four tall tires and any other modifications that may be required, which can push the total price up a great deal more. New tires are not necessary, but stock tires will look conspicuously small in higher wheel wells.
Lift kits can be self-installed with the proper tools and skill, but unless the car owner is a mechanic, it's probably easier to pay a reputable shop to install one. Many shops that specialize in 4x4 gear also have auto bays and skilled mechanics ready to perform modifications. Although US law prohibits manufacturers from voiding a warranty for installing an aftermarket part, they are often used as a cause for denying a claim, so people who install lifts will want to check with their dealership before doing so if the vehicle is still under warranty.