Steering Free Play
Steering free play is probably the number one complaint we hear about from coach owners at our shop. This happens when the steering wheel can be moved back in forth in your hands, but the vehicle is not steering. In other words, there is excessive “play” in the steering wheel.
It’s easy to understand why steering free play is such an issue. Many different components make up the steering action on today's motorhomes. In the steering components, you have the steering wheel, coupler, two or three universal couplings, the steering gear, sector shaft splines, the pitman arm, drag link, bell crank, tie rod ends, and the tie rod end sleeves. Generally, it is a cumulative effect, where several components contribute to excess play in the steering. We’ve seen everything from an inch or two of play in either steering direction to extreme cases where we wonder how the customer was even able to drive the coach!
In any case, steering freeplay is fairly common, and it can be reduced or even eliminated. We diagnose the problem with, what we call, a “Dry Park Test”. We put the coach on a rack with an inspection bay underneath. One technician is in the cab of the coach, moving the steering wheel back and forth. He looks for play in the steering shaft, steering U-joint or coupler, and sometimes even the steering wheel itself. At the same time, another technician is under the coach in the inspection bay. During this part of the test, we invite the customer into the inspection bay so they can see for themselves what is going on. A lot of shops want to keep the customer out of the shop, but we want customer to be part of the process up until the repair is initiated. I ask our customers, “If you were going to build your house on the side of a mountain, wouldn’t you want to know what the foundation is like?” The chassis is the foundation of your home on wheels, and we think it’s important for you to know what’s going on down there.
The first component we check underneath the coach is the steering gear box. Motorhomes use what is called a reciprocating ball type, and they usually have a certain amount of play in them by nature of their design. There has to be some play within the steering gear components, and that can often translate to play in the steering itself (we’ll get into steering boxes in detail in a future issue). We often stock blueprinted steering boxes on our shelves, or we can send yours out to be blueprinted, but there is some turnaround time involved.
Continuing on our path toward the wheels, we have to check the steering linkage that attaches to the steering gear box, which is called the “pitman arm.” Some pitman arms have replaceable joints that wear out, in which case we can replace the joint—but sometimes, the joint simply wasn’t tightened down properly at the factory and came loose. The “sector shaft” comes out of the steering box and has splines on it; if the nut wasn’t tightened down properly, there could be play in the splines, and the shaft can also be damaged in an accident of some kind, for example if the coach was driven off the road and struck a hole or large rock.
The next component is called the “drag link”, which can wear out, and can often be replaced by an aftermarket product. Finally, the tie rod joints and sleeves are checked for play, and if worn out can be replaced with products from a number of component suppliers.
On some steering systems, the steering linkage is supported by a mechanism such as an “idler arm” or “bell crank”. One of the things our manufacturing division, SuperSteer, is known for are the bell cranks we make to support the linkage on the P32 chassis, Freightliner XC chassis with straight axle, and the idler support we offer for GM pick-ups, vans and Class C motorhomes. The original equipment designs utilize a sleeve-type bushing, which can create looseness in the steering mechanism when it starts to wear out. The problem is, you can’t pre-load (adjust the play out of) a bushing without some degree of binding. Our products replace the sleeve bushings with tapered roller bearings. They are not only much better at carrying load, but can also be pre-loaded for precise movement.
On P32 chassis, there is also a component called a “bell crank arm”. This attaches to the bottom of the bell crank and to the steering center link. All of the pressure from the steering mechanism goes through the bell crank arm joint. The only way to diagnose play, in this component, is to start the engine and use the power steering. Otherwise, you can’t get enough force on the joint to make the play obvious. If this component requires replacement, SuperSteer also offers a replacement bell crank arm.
The looseness in the idler arm of GM trucks, vans and Class C motorhomes can cause changes in toe (where the wheels point inward or outward) as the vehicle drives down the road, and toe-in is the most critical tire wear angle. In fact, toe-in that is off by as little as 1/8-inch is equal to 28 feet of side-scrub per mile, which results in greatly accelerated tire wear. Our SuperSteer Idler Support features a stronger cast-aluminum housing and tapered roller bearings. Also, we designed a kit with Cognito Motorsports that ties in the pitman arm, center link and idler support for improved steering feel.
Last but not least, sometimes the front and/or rear leaf springs in Chevy P32, Ford and some Workhorse chassis can cause the sensation of steering freeplay. This can often be cured by a SuperSteer trac bar, but that’s another topic we’ll discuss in a later issue.
Steering freeplay doesn’t have to diminish your driving experience. With a little knowledge and a good alignment shop, you should be able to greatly reduce or eliminate the problem. Or, bring it by Henderson’s Line-Up the next time you’re in town. We’ll take care of the problem for you.