While many off-road vehicles can Greenlane or “two track” most un-surfaced roads, the desire of many off-roading enthusiasts is to attempt much more challenging terrain. The following listings show the modifications that are done and why:
Vehicle lifts – A vehicle lift is when the normal height of a vehicle is lifted to increase the amount of clearance between the ground and the bottom of the body or frame of the vehicle. There are numerous types of vehicle lifts:
Body lift – A simple and cheap way to lift a vehicle that has a body on frame design such as a pickup truck or some SUVs. A body lift consists of spacers placed in between the normal mounting points permit the fitting of oversized tires, but do not otherwise contribute to ground clearance. But because they increase the space between the ground and the bodywork they have the benefit to make bodywork damage less likely.
Suspension lift – A suspension lift is when modifications are made to the vehicle’s springs, shock absorbers, controlling arms and steering linkage. In this case small or short pieces of the suspension are replaced with longer or larger items of similar construction. Lifting a vehicle changes its driving dynamics and a suspension lift adds to the vehicle’s handling capabilities in relation to the increased height (see lifting concerns below). Some examples of this are:
- Larger arced Leaf springs
- Longer Coil springs
- Coil spacer blocks
- Leaf spring spacer blocks
- Longer Control arms
- Longer Pitman arms
- Air bag spring replacement
- Longer leaf spring shackles
- Reverse leaf spring mounting on the axle
- Longer Spindles in the front
Axle lift – Unlike a suspension lift, which only lifts the vehicle’s body, an axle lift can either be achieved by fitting larger other, have been modified to fit under the off-road vehicle of choice, e.g. Land Rover Defender, Jeep Wrangler.
An alternative is bolt-on portals which are fitted to the original axle flange. The advantages of this option are the limited work necessary, compared to modifying an axle to fit another vehicle.
Large tires – A quick and easy way to gain ground clearance is to increase the size of the tires on a vehicle. One advantage over body and suspension lifts is that larger tires will improve ground clearance under all parts of the vehicle, including the axles and differentials—typically the next lowest points after the tires.
While some vehicles can have larger tires added without a lift kit, such as a Ford F-250/F-350 pick-up truck which can usually take 33-inch (840 mm) tires before lifting is required, most will require a lift kit in addition to larger tires and, in some cases, bodywork modification such as cut back wheel arches may also be necessary.
Many off-roaders will combine different aspects of each of these vehicle lifting techniques, with the more experienced combining all of these items for a vehicle that could be lifted over 12 inches (300 mm) from its normal ride height.
Traction control – One of the main aspects of off-roading is to be able to keep traction on different obstacles. This can be done with more aggressive tread on tires as well as with help from traction control devices in drivetrain.
Some traction control devices used are:
- Locking differential
- Limited slip differential
- Four-wheel drive
- “Airing Down” – greatly lowering the air pressure in the tires
Dangers of vehicle lifting – While lifting a vehicle to gain ground clearance is helpful to off-roaders, it can also make a vehicle dangerous as, when a vehicle has been lifted, its center of gravity rises making the vehicle more likely to tip over in certain situations. Other dangers include loss of visibility of smaller objects and bumper height as compared to other vehicles on the road. In the United States bumper and frame height laws are in effect in most states to make sure that the vehicles on the road are not too much higher than their car counterparts.
Vehicle protection – A danger with off-after-market accessory. Skid plates may be simple flat plates, but they may also be formed (by stamping or by welding multiple pieces) to protect shaped items like differentials. Fuel tank skid plates are a common factory option.
Probably the most common improvement for off-road use is the grille or bull guard, which can be added with or without an improved bumper. These typically metal frameworks extend to protect the front grille, and potentially the headlights as well. One common type used prerunner bar and grille guard can be fitted. Bumpers designed for off-road use typically have added eyes or D-rings to assist in vehicle recovery.
Another common off-roading accessory, “exocage”. External cages help protect the entire body of the vehicle in the case of a rollover or slide into an obstacle.
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