The U.S. military is turning to a retrofitted suspension system to make MRAPs designed for combat in Iraq safer when they are redeployed to the rocky, mountainous terrain of Afghanistan.

During a demonstration at Aberdeen Proving Ground, Md., a Mine Resistant Ambush Protected vehicle shook violently as it descended a steep hill. But it made it to the bottom with no real problems, according to a Wall Street Journal report.

"You’d never even have tried that with an old MRAP," military contractor Mark Jackson told the Journal. "It wouldn’t have made it even halfway down the hill."

The military is attempting to adapt to ground conditions faster than it did in the early days of the Iraq war. In the period after roadside bombs became prominent in Iraq, troops resorted to welding their own armor on their vehicles for extra protection.

"The MRAPs were bought for Iraq," Marine Brig. Gen. Michael Brogan told the Journal. "They weren’t bought with any vision of needing to handle the rough terrain that’s common in Afghanistan."

The problem, the Journal wrote, is the MRAP’s design, in which both sets of wheels are connected to a single axle. This kept the wheels from moving independently on rocky, uneven surfaces.

Military engineers worked with civilian contractors to develop the independent suspension systems, allowing each wheel to better absorb the shock, the Journal wrote. They also added additional shielding to the underside of the vehicles to protect against explosions.

At a cost of about $100,000 per vehicle. the military hopes to retrofit all 1,000 MRAPs in use in Afghanistan. To date, only five have received the new suspension system.