[77newell]

Perhaps we could consider comparing to a Prevost coach, they have similar configuration and all the dynamics we experience. Has anyone driven a Prevost and can give us their experience of how it drives in comparison. I doubt commercial bus drivers would tolerate steering wander many of us experience, but I could be wrong. And if they do drive better the what are the mechanical differences that "drive" that? If they don't drive better then we probably have as good as it gets.

[whatsnewell]

I have to agree with Guy......the steering on my 1982 is wonderful. I can take my hands off the wheel and she just goes straight. Of course, then there is strong wind from either side.......then I have to over steer one direction, or another.....wears me out!

[ccjohnson]

Sounds like you have something worn or out or out adjustment.  Possibly wheel bearings?  Tie rod ends?  king pins? Steering gear box?  Also maybe check tire pressure.

[Richard]

I had originally intended this thread to explore why the truck drove better than a coach on a design or principles basis.

Your replies were good and on target. It was pretty silly of me to think that you had intimate knowledge of all the things I have done in aligning the current coach and previous coaches over the years.

On the current coach, the toe in is set at 3/16 to 1/4. My previous post on this shows that I think due to wear in the system that there is a difference in the toe in set on a turntable alignment rack and the actual toe in when the coach is rolling. By rolling I mean to roll the coach forward twenty feet or so and allow the tire forces to act on the suspension components. I don't have data to prove this, but I think this situation was made worse when I changed to the 365 tires. The toe in was set at 3/16 on the alignment table but when measured after rolling the tires the toe in was actually toed out. By the way, it wandered a bit, in the toed out condition.

I have changed tie rod ends, and drag link ends to new. I have measured the play in the center link ends to be .030 in total. I plan on replacing those as soon as I come up with a solution to an unobtainable part.

I have adjusted the freeplay in the steering gear box to it's minimum using a dial indicator.

When we get the coach to Florida, I will probably take it over to Josam in Orlando and have them put more caster in to generate straight line stability.

I have driven a handful of Prevosts. I can't say that the steering sensation was dramatically different than the Newells. Certainly not the difference I immediately felt in the truck.

I think if you drove my coach, you might say what am I whining about. In my pursuit of steering perfection, I am trying to understand WHY that truck steered more precisely than my coach.

On a sidebar, just for Monday morning entertainment. I spent a day on a abandoned concrete parking lot aligning the previous coach after I had paid two different local truck places to do alignments. It did not drive well after the pros worked on it. So I used a homemade trammel bar. string, a digital level, and some basic trigonometry to make all the adjustments myself. It drove OK after that, but I was always curious how accurate I could have been with my redneck setup. So, on a trip we stopped by Miami and I paid Newell $600 to put it on the rack and tell me "I'm not touching it, it's on the money" Rhonda got a big kick out of that, and told me not to be so anal ytical.

I think Jimmy's answer was the most helpful." I have had a couple of old class C's that steered better than any of the bus's I have had. "

[br549hoffman]

This may or may not have a bearing on your coach but I have owned and driven both a 92 Prevost and 85 Eagle Bus the steering on both were similar to my 87 newell handled really well until getting side by side with a semi, Then depending on who was passing who you would get wind shear but that is not uncommon in and type coach. Trucks handle different primarily because there not a driving billboard " one 35-45 foot solid wall" that being said I added new shocks and super singles on the front of the 87 #131 newell coach and it made a world of difference in the handling and stability of the coach. I also took the steer tire from the front and added it to the tag axle as well

[77newell]

Given the perspectives thus far, I wonder if the difference Richard noticed withe the truck is also due to wheelbase length. The shorter it is the less steer input is needed to establish a change in vehicle angle to the road. Maybe the difference is that the corrections are not so much less frequent in the trucks and cars as they are proportionately smaller based upon wheelbase. This explanation would be consistent with the reported behavior of Prevost and reports that our coaches tend to go straight in flat road no wind conditions. I've experienced this with both my coaches AND complained about wander.

We can't change wheelbase, but we might consider reducing the diameter of the steering wheel. That would deuce the distance our hands travel to achieve an angular input.

One other thing I've noticed is that when I consciously slow down the speed and frequency of steer inputs the coach behaves better. This would be consistent with Richard's wondering about the effect of our forward sitting position.

I'm beginning g to talk myself into the perspective that most of our coaches are fine, the problem is mostly the result of how our brains interpreted the sensations produced by the configuration of our coaches.

[MrE]

Just a guess, but I'm going with weight ratio between front and rear axles. The handling of cars changes substantially between front, mid, and rear engine. Possibly putting a wing on the front to add additional down force on the front axle would make the difference? I do know that my 33' '73 was easier to drive in high cross winds than my 40' '86, but that could also be caused by the size of the sail. The '73 also had a leaf spring front end with airbag assist.

[HoosierDaddy]

Jon (MrE), I think you are on to something. Please allow me to modify your idea as an attempt at humor. I propose front and rear horizontal stabilizer wings that adjust "on the fly" to balance weight loading on the respective axles....Actually they could adjust to add lift thus removing weight as needed. ;-)

[Richard]

Thanks to all for your inputs. I have been thinking about your comments.

I think Jon is on to something about wheelbase length. I do believe that the combination of wheelbase length which contributes to slow reaction to steering inputs, and the effect of sitting in front of the wheels which exaggerates the side to side movement leads me to the feeling of impreciseness in steering. Thanks Jon, these were factors that I didn't previously consider.

I do totally agree that air pressure and weighting of an axle change handling. However, the experience I had with the truck didn't really change the overall handling. I drove it empty, I drove it with a heavy load on the front axle when the load had my rollaways in the front of the truck, and I drove it with the rear axle heavily weighted when the last half of the truck was packed out. I weighed the truck on both loads so I have axle weight data to corroborate the loading. The best drive was with the front axle heavily loaded or the truck empty. When the rear axle was weighted more, the steering became slightly more twitchy, but the overall characteristics of the truck didn't change.

I also hadn't taken the aerodynamics into consideration. We are driving a barn door/sail and given the surface area of the sides, any slight change in the air pressure on either side of the coach is going to result in a side to side movement. I am just wondering out loud if the vortex generators installed at front and back would change that in any way.

[ccjohnson]

One thing that entered my mind is the belief that our large tanks, both fuel & water are not baffled. This can result in some sloshing which can affect handling. We usually travel with everything full except black tank. We also upgrade our steer & tag tires this trip out and I have noticed a big difference in handling.