Class C Stability

[Otisthecamper]

I have been thinking of buying a 30' class c motor home.  Possibly a new one or slightly used one. I talked to a person who used to own a 2 year old class c and he said driving it scared him so bad that he sold it.  He said semi trucks and wind gusts almost blew him off the road.  He also said he had a lot of extra aftermarket parts installed that promise to make driving safer but they were very little help.  Are they that bad to drive or could he have been exaggerating?  Is it necessary to add aftermarket parts to make the ride more stable and safe or are new and late models already equipped with such items?

 

[Harvard]

Some E350/E450 have handling issues, some do not, the following may explain the difference:

Ford ships all E350/E450 cut aways with identical fixed, non adjustable
caster/camber collars, "one size fits all". You can recognize these collars
because they are keyed and cannot be rotated. They are marked
"F8UA-AA 0+.25" on the passenger side and "E97A-CA +0-0" on the drivers side.

The RV builder almost never changes the Ford collars, as a result:

If the final RV build is nose down one degree then the runtime caster will be about +3.5 degrees.
These units can have a real wandering problem.

If the final RV build is nose level then the runtime caster will be about +4.5 degrees.
These units are probably indifferent.

If the final RV build is nose up one degree then the runtime caster will be about +5.5 degrees.
These units are probably just fine, possibly excepting the 31+ footers.

So, some RVs have a problem with wandering at highway speeds and some do not have a problem. JMO.

POPULAR MECHANICS MAY 1973:
START QUOTE:
If too little caster exists, the car will wander and weave,
thus necessitating constant corrections in steering.
END QUOTE:

 

[Gary RV_Wizard]

Nose up or down is just another way to describe the balance of weight in the RV. When it leaves the factory and gets aligned, the RV is empty, so likely nose-up and fine. Later the owner loads in his gear and passengers, typically maxxing out the weight to the GVWR, and the alignment changes as the suspension settles to its new attitude.  Re-aligning when load may help, but sometimes it is still off-balance enough to get the optimal caster. Camber may be affected as well.

 

[TheBar]

As said above alignment is key, tire pressure, and cargo weight. My 22 year old 30' Class C is not scary when semi trucks pass. Over inflated tires make it twitchy.

 

[Larry N.]

I talked to a person who used to own a 2 year old class c and he said driving it scared him so bad that he sold it.  He said semi trucks and wind gusts almost blew him off the road.

Excessive pressure in the front tires can cause much of that. Weigh the coach (axle by axle -- better yet, wheel by wheel) and check that against the tire manufacturer's inflation tables.

 

[Isaac-1]

A lot depends on he individual RV design, and how it is loaded, too much RV on too light of weight Chassis is going to result in poor performance, unfortunately lighter E350 chassis are cheaper than (possibly optional) E450 chassis, and we all know how the RV industry loves to save a penny.  Also many of the aftermarket suspension upgrades will have handling benefits, though they will rarely make a night and day handling difference, often the best bang for the buck handling improvements can be achieved by proper weight loading ,put the RV on a set of scale and move heavy cargo around to balance it correctly, properly inflate the tires using a tire manufacturers load chart (more pressure is not always better) https://www.goodyearrvtires.com/pdfs/tire-care-guide.pdf and get a proper front end alignment.

 

[ArdraF]

We've had three Class Cs (18', 22', 30') over the years and didn't have that problem.  Like others said, it depends on design and many other factors.  A shorter wheelbase with a high profile can be a contributing factor as can what I call "skinny" tires that appear to be the minimum needed for the chassis, especially if they're under- or over-inflated.  We always load our vehicles and then weigh them, occasionally rearranging items to even the load on each axle.  We also make sure our tires are properly inflated per manufacturer specs.  When looking at new motorhomes we've always looked for ones with a longer wheelbase and less overhang, both of which affect handling.

ArdraF