Hard to stay in lane on highway?

[nosebreaker]

We picked up our used 2018 class C last weekend with 12k miles, and on the drive back we noticed it was significantly harder than a car to keep in the lane. I've had experience towing a heavy trailer with a F250 before so I was surprised at how tiring it became to drive. We were constantly correcting it to stay in the lane while driving, especially on the highway. I am not sure if maybe a tie rod or bushing or some other part is somehow already worn out, there did seem to be a bit of play in the steering wheel. Do you think this is normal? I was going to take it to the dealer to look at but don't want to waste their time if it is a normal behavior.

[ron_dittmer]

At the risk of repeating myself.....

Motor homes are built in all kinds of sizes, shapes, weights, weight-distributions, and wheel-bases. It is not possible for chassis manufactures like Ford, Chevy, Dodge, and Mercedes, to set the final front wheel alignment prior to leaving their assembly line.

When shopping for a "new" motor home, it is critical the accomodations and amenities work for you and the people you travel with. It is NOT how the rig handles.

Handling issues are inherently going to surprise most new owners. An around-town test drive of an empty new rig will feel much differently than when loaded up on a trip, rendering the test drive misleading.

I strongly advise to get the house that works best for you and your budget, and then address any handling issues afterward. There are solutions to handling problems. Just be prepared and budget appropriately.

All the test-driving homework in the world will mislead you after loading your family, goods, water, propane, 55 gallons of fuel, a tow vehicle, etc. and rolling on the open highway with trucks passing, gusting cross winds, sloloming down canyon and mountain byways. A test drive of the rig you are set on is a good idea to get a general feel, but don't be critical over how it handles for it will change when loaded and rolling on a trip.

[tatest]

Harder than a car to keep in a lane? Always, because a car is using 5 to 6 1/2 feet of the lane, your RV 7 1/2 feet, and car drivers drift to lane edges and beyond all the time.

Constant corrections, all driving is constant corrections. On a larger vehicle the corrections might be more forceful, more steering wheel movement against greater force at the wheel. My Class C RV is a lot of work compared to the full size van, mid-size sedan, compact pickup I've driven during my years with the C, but not as bad as the subcompact hatchback with zero-feedback electric power steering. Most unstable vehicle I've ever driven was the little VW bug, even compared to the Renault R-8 I briefly owned.

But you've towed with a HD pickup, so you know different vehicles handle differently. While a motorhome will sometimes respond to side winds opposite those felt on a truck pulling a high-sided tow (which is somewhat stablizing compared to a single big box with a long overhang) it shouldn't be that much more work compared to a heavy pickup.

Something is not right with the setup, and I would start with tire pressures. Pressures need to be adjusted to actual (or at least approximate) axle loads. Heavier Class C RVs come with tires that are max rated for rear axle loads, and usually tires on front axle need 60-75% of the tire's max load air pressure. Fill the fronts to the number on the sidewall (meant to carry maximum load on the rear) and you reduce contact patch by 1/4 to more than 1/3, and steering gets really loose at speed.

If it is still loose after getting tire pressures right, get the alignment checked. For less front wandering (trading against more effort for steering), get the caster adjusted to the maximum end of the allowable range.

Wind is always going to be a problem, but there are aftermarket centering devices that fight against off-center forces that help to some extent, until the amount of steering correction needed for the wind gets you into fighting the centering device.

[flyingsquirl001]

the best advice I got in terms of a wheel alignment was to take my class c to a heavy duty truck shop. Find a place that specializes in dump trucks and school busses. One cannot go off of factory specs for a cut-away chassis.

I’m also another vote for weighing and adjusting tire pressure.

[klutchdust]

Bordercollie wrote:
Agree with Luvlabs. Before you spend real money on suspension upgrades, give yourself some time behind the wheel to get used to the handling of a Class C. They tend to wander a lot more than a car due to wind and cross-wind conditions, dips and crown of the road, turbulence from passing big rigs and even from passing cars. Adjustment of caster by a good truck alignment shop seems to be the most common first attempt to improve steering , load the rig as recommended above.

I take claims of "handling like an SUV", after spending big bucks on suspension upgrades, with a grain of salt.

PS: Class C's have a harsh ride mainly due to stiff "box truck" rear suspension. Some have had rear springs modified for less stiffness. I advise taking breaks at rest stops every 100 or 200 miles, getting out and resting on solid ground to conserve your nerves.

I have driven many different size vehicles down the interstates including big rigs and when I drove my Class C home from Minnesota to California it was a totally new experience for me. It wandered, leaned, drifted on the trip home. I just adjusted the movement slightly with the steering wheel and also tried different speeds. My rig likes 65 MPH on the open road. If I go 70 it feels looser on the front end. I watch for big rigs and let the air disturbance push the rig a little and then it just comes back to straight with little effort on my part. Trying to steer to compensate doesn't work. Relax and get the feel of your rig, start out at slower speeds. It's been said that a motorhome is basically a kleenex box with wheels, aerodynamics don't exist.
Larger vehicles will definitely have an effect.
Alignment on mine made a HUGE difference, that and all new shock absorbers.

[Bordercollie]

Agree with Luvlabs. Before you spend real money on suspension upgrades, give yourself some time behind the wheel to get used to the handling of a Class C. They tend to wander a lot more than a car due to wind and cross-wind conditions, dips and crown of the road, turbulence from passing big rigs and even from passing cars. Adjustment of caster by a good truck alignment shop seems to be the most common first attempt to improve steering , load the rig as recommended above.

I take claims of "handling like an SUV", after spending big bucks on suspension upgrades, with a grain of salt.

PS: Class C's have a harsh ride mainly due to stiff "box truck" rear suspension. Some have had rear springs modified for less stiffness. I advise taking breaks at rest stops every 100 or 200 miles, getting out and resting on solid ground to conserve your nerves.

[luvlabs]

Timeout! Before you do anything that involves spending thousands of dollars try the following (they cost nothing but a little time):

1. Weigh the coach and get your tires inflated to hold the weight you are carrying.

2. Drive it and then drive it some more. When you get 3-4000 miles under your belt, then make the suspension mods, if you still need them.

A driving tip or two for you: 1) Drive with your eyes a 1/4 mile or more in front of the coach; 2) lock your elbows into the arm rests and only steer with your wrists - this will prevent the oversteering that is common to all new motorhome drivers.

Keep a log of your driving experience. Note things like wind (direction and speed), crown of the road, type of road (interstate, US highway, state or local). Effects from passing trucks, etc.

When you decide you need upgrades, you have a much better idea of what you want to fix.

[CharlesinGA]

Before you go in for alignment, go ahead and order in two Ingalls Engineering 59400 double eccentric alignment bushings, and take them with you when the alignment is performed.

It is highly doubtful that the shop will have these bushings, they almost certainly will need them, as the stock Ford adjustment won't go that far (-5°) in most cases, and if you don't have them, they will charge you alot more for them and you will have to make a second trip to get the alignment finished.

Charles

[S1njin]

I'd love to drop some PSI in my rears as I think I'm riding on 4 rocks back there, but w/o a true corner weighing I have no idea if I have one corner significantly heavier then the other corner.

I'm guessing we can get away w/ that on the front axle given there is less up there configuration wise that could really throw things off kilter?

[ron_dittmer]

Hi nosebreaker,

Your new purchase likely needs some suspension work. But before you start investing bigger money, start with the lower cost ones that are certain.

As others have mentioned, start with the proper tire pressure for the weight of your rig. The 2 front tires will likely require a different tire pressure than the 4 rear tires. Too much air in the front tires will cause constant steering correction. Not enough in them increases the risk of a front tire blowout. Too much air in the rear tires causes a very bumpy ride. Just like the front tires, not enough air pressure increases the risk of a tire blowout. The right tire pressure will not only improve the handling and reduce risk of a blowout , but also yield proper tire wear, maximize braking performance, and provide good fuel economy. And BEWARE, not all tire gauges are the same as I learned HERE. They can vary by an alarming amount.

Also as others mentioned, get a front wheel alignment done with your rig loaded as if ready to leave on a trip including a full tank of gas and fresh water, personal effects, food, cookware, everything in it's place. If you can, add weight representing you and your spouse in the front seats (actually just behind those seats so the vehicle can be driven). This because the load and how it is distributed, affects the wheel alignment.

With our motor home built on a 2007 E350 chassis, we needed a lot of help in getting our rig to handle nicely. We needed the following suspension upgrades in addition to a front wheel alignment and proper tire pressure.

- front & rear heavy duty stabilizer bars
- heavy duty shock absorbers
- rear trac bar
- heavy duty steering stabilizer

Our driving experience changed from exhausting to relaxing. It went from two hands holding tight and correcting all the time, to one hand holding the steering wheel steady with only minor adjustments, and a cup of coffee in my other hand. This even with trucks passing and gusting crosswinds.

People don't realize the varying dynamics of each motor home. Each brand and floor plan will have their own unique driving characteristics. Many rigs have the main frame lengthened which changes the wheel base. Almost every class C motor home has a rear frame extension, rear of the rear axle which lightens the front end creating the floaties. These days most have a heavy slide out or two or even three which further adds variation. Their various heights and shapes influence aerodynamics which affects handling in other unique ways. The worst handling rigs are the shortest ones because the wheel base is short yet the rear over-hang is most often as long as mid-length rigs. That ratio of over-all length to wheel base will be an indicator for what the owner can expect.

That is why it is impossible for the chassis manufacture like Ford to set the alignment. They don't know what the end-product will be.

So the good news is that something can be done to make things right. The bad news is you are not done spending money on your rig. If you have a shop do everything for you, it will cost as much as $4000. If you buy everything yourself and install them yourself, you will cut the cost in half, maybe even more pending the deals you find on the internet.

[Photomike]

If it is newer it should have warranty so I would take it back to the dealer or a auto dealer and have them look it over. Doing anything while you still have warranty is foolish till you eliminate a build issue.

[S1njin]

I would respectfully disagree w/ the suspension of a 2018 not needing anything. They still roll off Ford's line w/ the incredibly wimpy sway bars fore and aft. Might be good for a van or something else with a reasonable profile, maybe even a short box truck. But not a motorhome, especially since most are on a stretched chassis.

Can you drive one w/o anything? Sure you can. I bet you wouldn't want to though after you drove one that had a owner who had it dialed in w/ mods that address stability.

[Desert_Captain]

As noted above the OP needs to get his rig weighed and the tires inflated to the load they are actually carrying. If that does not cure the problem then take a look at the alignment with an eye towards the caster adjustment previously described. The suspension of a 2018 should need no additional aftermarket equipment to drive and handle well.

Overinflating the front tires will make generate loosey goosey steering {as this dramatically reduces your tires contact patch with the road} with passing trucks blowing you all over the road and don't even think about driving this way on a windy day. :S
Ignore the door sticker psi numbers as they are worse than worthless. What matters is your actual weight being correctly supported by the correct psi as determined by the tire manufacturer.

I have to ask the OP... did you not take a thorough test drive? If you did why would you buy a coach that handles and drives this badly without investigating cause and cures before completing the purchase? :h

[Harvard]

Ford ships these E350/E450 Cutaways off the assembly line
with +3 to +4 degrees of Caster. Those settings are
OK for city driving BUT you want to have +5 to +6 degrees
of Caster for highway driving, OTHERWISE:

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:

There are at least two ways to increase the effective
runtime caster (see Self Aligning Torque):
1. Decrease the tire inflation pressure to the required
minimum for load (to increase Pneumatic Trail), and or

2. Increase the caster angle during an alignment
(to increase caster trail).

If you find an improvement in reducing the tire pressure
you will be amazed what it is to add +2 degrees of caster. IMO.

The specified range of Caster for the E350/E450 is
from +1.5 to +7.0 degrees. As you can see
almost any possible setting is "within spec"
for the "tweak the toe and you are good to go"
alignment services. Stay away from Ford
dealerships and have it done at a "good" truck front end shop.

Our experience. Circa 2010

[DougE]

Twin I-beam Fords prior to 2009 had the issue memtb is referring to. There are caster adjustment bushings on the market to dial in more caster on those Fords. The original poster needs to give brand information to get more knowledgeable input. Low air pressures will cause wandering. It's unusual for a unit this new and with as few miles to have wear problems. I would take it to a good alignment shop prior to going to a dealer.