Personal project, 2021
The Jeep Gladiator is part Jeep, part pickup truck. Consequently, it has the longest wheelbase of any Jeep ever made. While this allows for a very practical truck bed, it also makes for a terrible break-over angle when trying to drive over off-road obstacles. The solution to a terrible break-over angle is to add suspension lift, but that would have a negative impact on day-to-day usability and fuel economy.
My solution was to realize the best of both worlds – to have a tall Jeep when driving off-road, and to have a lower Jeep when driving on the highway or loading cargo in the bed.
Actions:
My first approach to any engineering problem is to look for existing solutions. Though there were no off-the-shelf kits available for this vehicle, I did at least confirm that the traditional solution to vehicles requiring alterable ride heights is to use air suspension.
I then calculated the weight for each corner of the suspension and derived an approximate air bag diameter required to support the vehicle at a reasonable air pressure. I sourced a commercial vehicle air bag that fit my requirements and set to work designing and building new spring mounts to put the air bags in place of the Jeep’s original coil springs.
Since the original design relied on the shock absorbers to limit the suspension droop, I procured some second-hand shock absorbers with additional length. With longer length comes a longer collapsed length, so I also designed and built new bump stops for the front and rear axles to prevent bottoming out and damaging the new shock absorbers.
The air bags are of little use without a means of inflating and deflating them. For that purpose, I installed a small air tank, high-volume 12-volt air pump, and 8-channel air valve. These were strategically hidden such that no cargo space inside or outside the vehicle was compromised.
My original plan had been to install a set of manual switches for the air valve. However, partway through this project and while I was holding my phone, I realized that I had the perfect wireless controller already in my pocket. I set to work installing an Arduino with modules for relay control and Bluetooth wireless communication.
I coded an Arduino program to live on the Jeep, which was relatively easy given my existing Arduino experience. I then taught myself to create Android applications and to use the phone’s Bluetooth radio to communicate with the Arduino and independently control the height of each suspension corner, as well as air compressor functions.
Results:
At the time of this writing, the new suspension has been in place and reliably operating for over two years. Ride height is adjustable within a window of 10 inches, improving the break-over angle by approximately 60% when at full height. With independent control of all four corners, the Jeep can be leveled to correct for off-camber trails and obstacles or varying loads in the bed or on the trailer hitch. By all accounts, the ride is very comfortable.
Matt Mundell 