This specification affects motorhome ride and handling and also component life.
By Brett Wolfe, F252125
December 2011
Safety caution: Never work under a motorhome without using adequate safety stands.
Correct ride height is important. If the ride height of a motorhome is too low, the suspension can bottom out on bumps, result in a harsh ride, and crush the shocks on compression. If the ride height is set too high, the shocks can pull apart on extension and the motorhome’s center of mass is raised. Ride height that is either too high or too low can destroy the U joints and driveshaft, particularly on a diesel pusher. Even 1 inch out of spec on an 18-inch diesel-pusher driveshaft significantly alters the driveline angles. It also can transfer a huge amount of weight from side to side. How many of your really strong friends would it take to lift the left rear corner of your motorhome?
Ride height is critical to ride, handling, and component longevity. All chassis makers have specifications for the correct ride height “” leaf spring, Torsilastic, and air suspensions. A proper wheel alignment cannot be done before correcting ride height. Ride height specs are generally from a given point on the axle to a given point on the chassis rail.
Here are methods for adjusting the ride height on the three suspension systems listed above.
Leaf spring suspension: Out-of-spec ride height on a leaf spring suspension can be caused by worn springs, shackles, or out-of-spec weight on a corner. It can be corrected by replacing the springs, adding a spacer shim, adding a leaf, or moving weight. Truck suspension shops make these repairs routinely.
Torsilastic suspension: On the BFGoodrich Torsilastic suspensions found on some Foretravel and Safari products, ride height is raised by removing the spacer shims. Each shim is 1/4-inch thick, and removing one from in front of and behind a wheel position raises that wheel position ¼-inch. Loosen but do not remove the long bolts securing the shims. The shims are slotted and are removed easily. Torque the nuts on the long through-shim bolts to 115 foot-pounds once the shim is removed.
Air suspension: Most motorhomes with air suspensions use three ride height valves “” two on one axle and one on the other. These valves can leak and/or the light rods used to attach them to the axle can be bent easily by road debris. Check and adjust ride height at least twice a year or anytime you run over road debris; notice a change in ride height or ride quality; find that the coach is too low for the jacks to deploy properly, or the steps are closer to the ground, etc.