Add-on air suspension smooths RV's ride

September 02, 2005|by JEFF JOHNSTON/Motor Matters

Motor-home owners appreciate a comfortable driving experience. After all, that's part of the reason someone choose a motor home, isn't it? Enjoying the ride, and getting there in comfort, is part of the fun of recreational vehicle travel.

Workhorse Custom Chassis is a popular manufacturer of Class A motor-home chassis. The company has sold a variety of chassis models for many years and is well known to the motor-homing public for its practical, well-engineered products. Workhorse has recently introduced two new products that could dramatically improve the ride and performance of its gas-powered chassis models.

An all-new replacement air-bag suspension system is now available to fit the Workhorse W20, W22 and W24 chassis models. The hardware, known as the Stabil-Air Suspension, replaces the stock steel leaf-spring suspension parts that are standard on all three chassis. Motor-home chassis built on model-year 2000 and later can be fitted with the new system.


Air bags are commonly used on large, expensive diesel pusher motor homes, and most lower-priced rigs use leaf springs for economy reasons. While the Workhorse leaf springs are about as sophisticated as such springs can be, some owners still find them a bit too harsh for a motor home that's supposed to be comfortable on the road. This new Workhorse air-bag system makes it possible for drivers of leaf-spring equipped motor homes to enjoy the benefits of air ride without tackling the huge initial cost of a coach so equipped from the factory.

The Stabil-Air system includes replacement parts for supporting the axles in place, as well as mounts for the air bags. The bags are outboard of the frame, which creates a wider suspension stance for reduced body roll and lean in the corners. A Firestone IntelliRide control system monitors the coach ride height and maintains the proper air-bag pressure. The system adds air when the coach is heavily loaded and reduces air pressure when there's less payload aboard so the rig drives at a consistent height.

In addition, the control function provides an "off road" air bag setting and a "kneel" setting. The "off road" setting raises the coach body about 3 inches to reduce bottoming-out when driving into or out of a gas station with a deep gutter by the curb, for example, and the "kneel" adjustment drops the coach between 2 and 2.5 inches to make climbing in and out easier and to facilitate leveling. The unit's auto-level feature varies the air pressure in each bag to level the coach on uneven terrain, within the lifting range of the air bags, of course.

The system has a built-in fail-safe should there be a catastrophic loss of air pressure. Each air bag includes a built-in bump stop, and if the bag collapses, it allows the driver to keep moving the coach to a safe location or a designated repair facility. The ride will be a bit rough at that point but it beats being stranded.

At the moment, the Stabil-Air is only available through the Workhorse aftermarket parts division. You can't order a new motor home with the air suspension right from the factory, although that could possibly happen in the future.

The Stabil-Air carries a $3,395 MSRP, plus the cost of approximately 20 hours of installation time by a professional shop.

Workhorse has further upgraded some of its models with new six-speed automatic transmissions. For model-year 2006 products, the Allison 2100 MH series has been bumped up to six speeds and is used in the W24 chassis. The slightly smaller Allison 1000 MH transmission has likewise been fitted with six speeds and is used in the W20 and W24 chassis models.

The new units feature two overdrive gears at the top end. This allows the manufacturer greater flexibility in designing the best possible coach powertrain combination. The powertrain, rear axle ratio and so on may be tailored to work best with the engine power output, coach weight and such. The extra-"tall" overdrive ratio can result in lower engine rpm at highway speeds, which translates directly to a quieter ride with less vibration and possibly even some incrementally better fuel economy.

In addition, the company uses Castrol TranSynd synthetic fluid in the 2100 transmission. This extends the warranty to five years or 200,000 miles, which is way beyond the mileage most motor-homers put on their vehicles. The scheduled maintenance interval is also doubled to 48 months or 100,000 miles.

For more information about the new Workhorse products, phone (800) 309-7163 or go to

Copyright, Motor Matters, 2005

The Herald-Mail Articles