Handling issues

Vach wrote:
On the highway it tracked straight as long as there were no bumps, cracks or grooves. Very rough ride. Not teeth rattling but rough. Rocked and rolled around corners. My wife can drive my truck pulling our tailor but don't see her driving something like that.

First, I'm not buying into the idea that manufacturer's have their head up their tail pipes when they specify a chassis. TODAY!!! They choose some thing that will carry the weight and the suspension is designed with that in mind by the chassis manufacturer. Coach builders generally specify a long list of OEM suspension options.

OK.... Let's take a gradual approach. What you are describing... rough transitions over bumps, cracks or grooves and generally a rough ride may relate to the tire pressures. There's an 'old school' herring that assumes that more is better (up to the pressure on the tire's side). That's often not the case. There is a placard on the driver's side door or frame that specifies tire pressures. That pressure is for the FULL RATED GROSS VEHICLE WEIGHT. So, it may be too much pressure for a lightly loaded vehicle. Lowering the pressure by a couple of pounds will soften the ride appreciably because you are getting some side wall flexing in the tire. Now folks are going to jump in here and start talking about low pressures and blow outs. That's only true if the tire is extremely under inflated. What's really going on here is you set the pressure a couple LBs lower than the data plate. (It would helpful to know the actual weight but not so necessary.) As the tire heats up it will increase in pressure about 1 LB / 10 degrees F. The idea is to find just the right pressure to give you a smoother ride while more closely approximating the pressure actually required for the weight of the vehicle.

Next, rocking and rolling around corners. Very typical of a heavy vehicle with a high center of gravity... like most coaches. So, go slowly around corners or through those road situations that cause the rocking and rolling. Before you jack around with all kinds of suspension upgrades, shocks, roll bars, sway bars, etc.. go back to step one above. If the tire pressures are too great for the weight, you lose the compliance and shock absorbing ability in the tire. And, yes! The tire is part of the suspension. If they are a little less stiff, they will begin to absorb and dampen some of the forces earlier that are creating the sway. Sort of like extra shocks... of big rubber airbags, if you will. You will never eliminate it... and you don't want to... but you can reduce the swinging moments by letting the tires do some work.

Just a couple thoughts...