Most 4×4 can be used for rock crawling, but many standard vehicles will struggle. Most offroading vehicles are modifled in some form and outfitted with custom parts. Power is usually not an issue, as rock crawlers typically lower their gear ratios in order to drive more slowly over obstacles without stalling the engine.
Modifications can include:
- locking differentials
- taller off-road tires
- upgraded suspension
- four wheel steering
- roll cage for driver protection
- engine modifications for increased performance, mostly torque
- lowered gearing in either or all of the transmission, transfer case (including often times employing a second transfer case to reduce gearing even more), or axle differentials
- body armour (rocker panels, tube fenders, etc.)
- beadlocks (locks tires to the rims for low tire pressures)
Over-sized, low-pressure, knobby, mud-terrain tires are used.
Most vehicles have a low-geared transfer case to make the most torque in the low speeds used for rock crawling.
Suspension-wise, rock crawling vehicles sometimes have after-market lift kits installed, raising the chassis and increasing suspension flex, though the rock crawlers running the tougher trails often have fabricated suspension systems, or home-assembled leaf packs to cheaply achieve the goals, making it easier to drive over larger obstacles with less risk of damage to the vehicle. Most suspensions are made to be highly flexible, allowing for the maximum amount of tire area to contact the ground, while keeping the vehicle as low as possible.
Due to the conflicting nature of the dynamics and needs of rock crawling and road driving vehicles, it is not unusual to modify a vehicle solely for off-road recreational usage as on road handling will be severely changed (often not for the better for road use). If you want to go all out and make an extreme Rock Crawler then extreme modifications may result in your vehicle being deemed “off-road only” i.e. not driven on the roads and trailered to trails or off road centres. The modification possibilities are endless if trailering your vehicle isn’t an issue.
Those with the technical, mechanical and engineering know how can build their own rock crawler. The biggest benefit of this approach is that the owner has complete control over what their vehicle is capable of, since each part of the vehicle can be custom designed. Building your own vehicle also saves expense as no labour charges are applicable.