Suspension Limiting Straps:
Limiting straps are made of woven nylon, similar to that of safety belts and harnesses. They are installed to limit the suspension's extension travel during droop, before any damage is done due to over extension. Their lengths will vary to the suspension travel. The strap should be 1/2- to 1-inch short of the suspension's complete droop or extension travel. The straps are attached to the vehicle's frame and the shock mount bolt.
Layman's Terms: If you want to jump your rig and still drive it home, limiting straps will help to keep your suspension intact.
Spindles:
Lift kits often include an elongated cast spindle/steering knuckle, with a longer shank and relocated spindle shaft. The relocation of the spindle shaft will determine the new ride height.
Layman's Terms: The knuckle is what your front wheels are mounted to. Make sure your lift spindles are from a quality manufacturer.
Dropped pitman arm:
When we lift a vehicle, the OEM pitman arm must be replaced with a "dropped pitman arm." This arm will re-link the steering gear to the idler arm, acting as a lever converting torque of the steering gear to mechanical force for movement of the steering linkage. The pitman and idler arms are a weak link of the steering system when increasing wheel and tire diameter size, which increases weight. Always check these arms for extensive play and slop in the steering-wheel rotation.
Layman's Terms: If you like to steer your truck and not have it steer you, a new and more heavy-duty pitman arm is a very smart upgrade.
Coil spring:
A coil spring is made of wound heavy-gauge steel wire that will support the vehicle's weight. The spring can be located around a shock absorber, between a lower control arm and frame, or on a rear differential and frame. A coil spring may be conical or spiral wound, at a constant rate or a progressive rate, with variable pitch spacing or use variable thickness wire. When using coil springs in an off-road application, they will tend to sag with age. It is best to replace them in pairs to maintain an even ride height from side-to-side.
The spring rate is configured by the amount of weight it takes to compress the spring one-inch. These can vary in coil length, amount of coils, how tightly they are wound, and the wire diameter.
Layman's Terms: Coil springs are often used to lift a truck, most commonly with coilover shocks. When worn, they should be replaced in pairs.
Panhard bar:
The panhard bar helps to keep the rear or front differential from having any lateral movement. One end of the Panhard bar locates to the frame, while the other locates to the differential housing. It must be used when using a parallel four-bar link suspension.
Layman's Terms: The panhard bar is a vital ingredient when lifting a truck, it helps the suspension not to twist and cause excessive body roll.
Fasteners:
Any time you are dealing with suspension moving parts, we can't stress enough to use high-quality Grade 8 bolts. Do not use Nylock nuts. The Nylock material can distort or weaken, melt, and then loosen and unthread. Only use castle nuts with a drilled bolt and fastened with a cotter pin, or use heavy-duty lock nuts. Make sure you always use a flat washer on both sides of the bolt head and the nut. When tightening nuts and bolts, always allow at least three threads to show above the nut. It is better to use UNF, also known as united national fine, threaded fasteners due to the fact that there are more threads per inch and more fastening grip surface, allowing it to withstand greater torque.
It is a good idea to use anti-seize when threading nuts onto bolts as it helps eliminate galling the threads.
Layman's Terms: Spend a little more at first, and save yourself a ton of money and headaches later on.
Differential Gears:
When increasing the overall tire diameter, it will affect your vehicle's gear ratio. The increase in un-sprung mass and the increased leverage of a larger diameter tire will tend to reduce your truck's overall performance and fuel mileage. The factory rear-end gear ratio was calculated to be used with a specific tire diameter, in relation to the engine's torque and power output. For example, an O.E. 4x4 Chevy truck uses an LT245/75R16 as a standard tire. This tire is approximately 30.5-inches tall. General Motors offers stock gear ratios of 3.73 or 4.10. The following information will show you how the increased tire size will effect the engine's rpm.
Layman's Terms:It takes power to turn those monster tires, and new gears will help to send more of your engine's hard work to the pavement.
30.5-inch Tall Tire
Gear Ratio - 3.73:1; MPH - 75; RPM(Automatic) - 2,165; RPM (Manual) - 3,082
Gear Ratio - 4.10:1; MPH - 75; RPM(Automatic) - 2,372; RPM (Manual) - 3,388
33-inch Tall Tire
Gear Ratio - 3.73:1; MPH - 75; RPM(Automatic) - 1,995; RPM (Manual) - 2,849
Gear Ratio - 4.10:1; MPH - 75; RPM(Automatic) - 2,193; RPM (Manual) - 3,131
35-inch Tall Tire
Gear Ratio - 3.73:1; MPH - 75; RPM(Automatic) - 1,880; RPM (Manual) - 2,686
Gear Ratio - 4.10:1; MPH - 75; RPM(Automatic) - 2,192; RPM (Manual) - 2,952
37-inch Tall Tire
Gear Ratio - 3.73:1; MPH - 75; RPM(Automatic) - 1,778; RPM (Manual) - 2,540
Gear Ratio - 4.10:1; MPH - 75; RPM(Automatic) - 1,955; RPM (Manual) - 2,792
40-inch Tall Tire
Gear Ratio - 3.73:1; MPH - 75; RPM(Automatic) - 1,645; RPM (Manual) - 2,350
Gear Ratio - 4.10:1; MPH - 75; RPM(Automatic) - 1,880; RPM (Manual) - 2,583
Lifted Vehicle State Laws:
You can check your local state elevated ride-height laws by going to the authorities website: www.stateabbreviation.gov.
The website will give you all of the on-road and off-road information involving suspension limitations of a vehicle per weight GVWR and the ride height.