Tipping Point: Installing Roadmaster anti-sway bars
May 1, 2010
Filed under Tech Tips
The motorhome industry transitioned to a 7-foot interior ceiling height several years ago
to gain the visual impression of more interior space. It worked. But one of the trade-offs
soon became obvious, at least in some coaches built on leaf-spring chassis: excessive body
roll, or a tendency to tilt uncomfortably on curves.
It should be no surprise that a coach
that stands 12 feet 3 inches tall might heel over, at least moderately, on curves.
Nevertheless, it came as a surprise with a 2008 Itasca Sunrise 35A built
on a Ford F53 chassis. During a test drive with partial tanks of fuel and
LP-gas, little water and no personal supplies, the motorhome showed only a modest tendency
to tilt on curves and corners, and its overall road manners were good.
Loading a coach to its maximum gross vehicle weight rating (gvwr) – 22,000
pounds in this case – can be expected to affect handling, but not this much! On curves, a
different motorhome emerged; body roll was uncomfortable on curves even at lower than
posted speeds. In left-hand curves on uneven, crowned roads, the amount of lean to the
right often progressed to the white-knuckle stage for the co-pilot.
The apparent causes of
excessive body roll in this case included an excessively high center of gravity for a coach
built on a leaf-spring suspension, inadequate sway bars and a rather long rear overhang.
With other motorhomes, the need for better stability will vary with driver sensitivity and
with different chassis and coach designs.
Late-model air-bag-suspended diesel pusher
motorhomes tend to be equally as high centered as our test coach, but usually have better
road manners due to the dynamic stabilizing effect of their air bag suspensions. The Itasca
was fitted with Bilstein shocks, which are quite good, but shocks are not a significant
factor in controlling body roll.
The quest for solutions led us to Roadmaster
Inc. Renowned initially for its tow bars, the company expanded into anti-sway bars
(also known as anti-roll bars or stabilizer bars) and steering stabilizers.
For the 35-foot Itasca, with its 22,000-pound gvwr,
Roadmaster prescribed two of the company’s anti-sway bars: a 1
1/2-inch-diameter bar for the rear – in addition to the stock 1 3/8-inch Ford rear bar – as
well as a 1 3/4-inch-diameter front bar replacing the stock Ford 1 1/2-inch unit. Thus, we
were looking at three bars instead of two for this chassis, and it needed all three.
company also recommended the Reflex Steering Stabilizer, which consists of a hydraulic
damper inside a spring that is attached to the frame at one end and to the steering tie rod
at the other. While it has no effect, per se, on body roll, steering characteristics can
have an effect on a driver’s response to body roll, and is essential for driving comfort in
Roadmaster anti-sway bars are made of grade 4140 cadmium-plated chrome moly
steel for more stiffness, whereas the stock Ford bars are 1020-grade steel, according to
Roadmaster. In addition, polyurethane bushings used at all pivot points by Roadmaster are
more rigid than the stock rubber bushings, increasing effectiveness of the bars.
Anti-sway bars attempt to keep the coach as firmly upright
in relation to the wheels as is reasonably possible. The Roadmaster rear bar more than
doubles resistance-to-body-roll at the rear, and the front bar increases resistance
substantially over the stock bar. Roadmaster says roll stiffness is increased 30 percent
with each additional 1?8-inch in bar diameter.
The company recommends its Reflex Steering
Stabilizer since it applies return-to-center spring pressure and a steering damper effect
anytime the wheels are turned out of straight-ahead alignment.
After having driven the
Itasca for several thousand miles, a considerable portion of it on secondary roads that
were crowned, uneven and narrow, we were well-acquainted with how far this motorhome would
tilt on curves and in driveways, and how difficult it was to estimate what would happen on
the next bend in the road.
We arranged with one of
Roadmaster’s dealers, T&D Auto and Truck in Plainville, Mass., to install the
components, which took about three hours. Installation of the rear bar was mostly a bolt-up
procedure, beginning with two steel brackets that were attached below the axle. Eight nuts
on the U-bolts that attach the axle to the springs were removed, allowing placement of the
brackets. The nuts were reinstalled with plenty of threads showing.
The bar was attached at
four pivot points utilizing polyurethane bushings and clamps – two at the axle and two at
the frame. Four holes were drilled through the frame for attachment of linkage brackets
used to connect the forward tips of the bar to the frame.
Installation of the forward bar
was a direct replacement, using new steel brackets with polyurethane bushings. The tips of
the Roadmaster bar were connected to the frame using the stock Ford linkage.
We separated our driving test into several stages, first with the Roadmaster
anti-sway bars in place. Later we connected and disconnected the Reflex Steering Stabilizer
several times so it could be evaluated separately.
Our initial impression of the difference
created by the anti-sway bars didn’t take long; we were barely out of the driveway. As we
exited the installation shop driveway through the rain gutter into the street, the coach
did less of the whipsaw motion we had come to expect.
While heading through the town toward
a country road, the effect was apparent on pavement undulations: The usual wobble from side
to side was greatly reduced. While anti-sway bars will not eliminate body roll, they can
greatly reduce it, and we noticed this effect immediately.
The real test was on a winding
road. In each curve, a moderate amount of body roll would occur, and then we could feel the
buildup of the bars’ resistance. We began to realize and trust that we could drive winding
roads at reasonable speeds with a feeling of confidence. After several thousand more miles
of backroads, this impression endured; the bars had made a dramatic improvement and had
turned a coach that was very uncomfortable to drive on anything but flat, mostly straight
pavement into one that could handle mountain roads with comfortable and predictable
Oddly, crosswinds did not affect this motorhome as much as we had anticipated,
based on the amount of body roll that had been occurring on curves. During crosswinds up to
40 mph we had to reduce speed but didn’t feel like we had to get off the road. Even so, the
Roadmaster bars held the motorhome more upright, and made driving in strong winds more
Roadmaster markets the Reflex Steering Stabilizer as
an effective measure for handling front-tire blowouts, rut tracking, inadvertently
wandering off the edge of the road, potholes, driver fatigue and crosswinds. The unit
consists of a hydraulic damper inside a spring that is attached at one end to the frame and
at the other to the steering tie rod. The spring exerts no pressure when the wheels are
straight forward. When they are turned, the unit applies pressure to return to center. And
it dampens rapid steering movement. The unit is a simple bolt-on installation, after which
a bit of tweaking may be necessary if the stabilizer spring pulls steering slightly to the
right or left while driving straight ahead. Adjusting the tie rod bracket to achieve the
neutral position is easy, using a 9/16-inch socket wrench.
One of the most noticeable
effects of the Reflex unit on the Itasca occurred during strong, constant crosswinds, which
we encountered on several occasions, including an interstate highway trek westward across
Texas. The effort needed to constantly steer into the wind was noticeably reduced, along
with driver fatigue. The unit also helped quell the effects of gusting crosswinds and
pavement ruts by reducing the frequency and amount of steering correction.
retail prices for the anti-sway bars are $678 front and $918 rear. The Reflex Steering
Stabilizer carries a price of $384 for the unit plus $118 for a mounting bracket.
For More InformationRoadmaster Inc. 800-669-9690, www.roadmasterinc.com.