If you have a newer Class C motorhome or a Class A manufactured since the mid-1980s, there is a good chance that your coach has an air ride system with “air springs” as part of its suspension. The system may seem shrouded in mystery because its components are underneath the coach chassis. If everything is in good working order – out of sight and out of mind. But like all coach systems, the components are subject to wear and tear from use and should be inspected regularly.
The two primary components of your suspension system are airbags and shock absorbers. Most everyone is familiar with the latter because most cars and trucks have them, and they are an item that needs replacement every few years or after, say, 100,000 miles.
Air bags are rubber. The same type of rubber as tires. Rubber deteriorates with age.
What does the air spring system do?
The airbag system under your coach has three functions: First, the system lifts the coach to “ride height” or a level well above the tops of the tires when the coach is in the travel mode. Second, the air suspension levels the coach, both while underway and while parked in camp. And finally, the system provides a cushioning effect that substantially enhances the smoothness of the ride while on the road.
How does the system work?
The airbags are mounted forward near the steer wheels and the aft dual wheels. There are pneumatic lines that connect the bags to an engine-driven air compressor that inflates them and allows the operator to maintain a level coach body by adjusting valves with controls located, generally, near the driver’s seat. The valves let air out of front or aft airbags and/or left or right airbags to achieve level.
What do you look for when inspecting the air ride system?
Condition of airbags and pneumatic lines.
How can you tell when it is time to refurbish your air springs?
Airbags are tough and built to handle the inflating, deflating, and intense air pressure. But they are made of rubber, and rubber deteriorates with age, as with tires. Airbags should be inspected for integrity as a matter of pre-departure routine. The system should get special attention if there is any indication of low airbag inflation, airbag failure, the sound of an air leak, or failure of the coach to reach level ride height. In addition, if your coach is more than ten years old, it is time to start carefully inspecting for cracks in the rubber, heavy oxidization, or the appearance of bare cords (see below). An exposed cord should prompt an immediate plan for an airbag replacement, just like visible cords on a tire.
Replacement airbags and associated components are typically sourced from your coach manufacturer or many parts outlets, particularly those that supply Class A RVs or commercial trucks. There are also discount parts suppliers online, such as SDTruckSprings.com and FinditParts.com. It is worthwhile to shop carefully, referencing the specific part number(s), as there can be a wide range of pricing for a given airbag part number. I have personally seen a difference of as much as $80-$100 per airbag! A Class C coach with air spring-assisted suspension has two airbags. Most Class A’s have eight or more!
Do it yourself?
The handy motorcoach owner will likely consider doing an airbag replacement project themselves. However, remember that this project involves raising the coach, blocking it safely, and dismantling the air ride suspension system. Older coaches sometimes have rusted or corroded airbag attachment brackets which are very difficult to get off. Air supply valves and fittings might also be worn and require new parts, and sometimes those components are located in very tight quarters near the wheel wells and bulkheads. And again, I stress, if you are going to do any work underneath the coach, ALWAYS USE FRAME BLOCKS!
Leave it to the pros
In my case, in the end, I decided to leave it to the pros.
I found cracking and some bare cords on the airbags and called my favorite heavy-truck shop, Ross Point Truck Repair, in Post Falls, Idaho. Their truck chassis technicians change dozens of these systems out every year. They have the parts, tools, and know-how to get the job done right.
If your coach won’t level or ride right, or rides like a hay wagon instead of a Bentley, take a close look at your air ride system.