iata 5 28ss road handling

[mwk]

We recently (2 weeks ago) purchased an 2024 Isata 5 28ss 4x4, Dodge Ram 5500 Chassis, w/approx 4000 miles on the ODO. We are on our first weeklong trip to "shake it down". We are seasoned RV owners w/approx 200K miles logged on Winnebago Class A coaches, our recent previous was a 2013 42QD we purchased new.
We test drove the Isata 5 prior to purchase and had it 3rd party inspected by our long time RV shop mechanics .I have noticed mid-trip that this Class C does not handle predictably or responsively. I haven't weighed it yet, but don't think we are overweight, the tires are at correct pressure, and I haven't exceeded 65 MPH on any road or Interstate. we tow a 2008 Jeep Liberty, with an invisibrake system.
the behavior: The vehicle Wallows about; requires constant corrective steering inputs, and is easily diverted by road ruts; the steering is vague but seems to improve at increased speed (approx 65) but on back roads this is not safe. I am suspicious of the drive by wire systems, having had adverse situations with other vehicles.
Are there any Dynamax/Isata owners that have experienced this phenomena, and are there any solutions that you have had success with? This is an exhausting vehicle to drive; in my 20 years of motor home travel, I have not encountered this.

 

[BGMAC]

I don’t have your type of vehicle, but do have a straight axle on my class a gasser. We can have some wondering on ours and many add a steering stabilizer which helps.
Of course not being the same vehicle it’s not a very good comparison so I used ChatGtp and entered your vehicle and issue. Here is what it said.

For your particular symptoms, I’d focus on these

1. Front-end caster — very high on my list.
Insufficient positive caster can produce exactly the feeling you’re describing: vague steering, poor return-to-center and constant corrections. A motorhome conversion can also change the loaded attitude of the chassis.

2. Front track bar / track-bar mounts.
On a heavy 4×4, even a small amount of movement here can make the coach feel like it’s wandering or being pushed sideways when the road surface changes.

3. Steering linkage and steering box.
I’d want the shop to measure actual steering free play rather than simply looking at the components and saying they appear tight.

4. Motorhome body/subframe and weight distribution.
This is especially important with your vehicle. The 5500 is designed to be heavily upfitted, and Ram specifically markets the chassis for a wide variety of upfits. The way the motorhome body is mounted and where the weight sits can have a substantial effect on handling.

5. Tire pressure and tire type.
I would not automatically run the maximum pressure molded on the tire. The coach should be weighed, ideally each axle and preferably each individual wheel position, and tire pressures set according to the actual loaded weights and tire manufacturer’s load/pressure table.

One important question

When you say it “wallow about,” do you mean the whole motorhome rocks/leans from side to side, or do you mainly mean the front end wanders left and right and you have to steer constantly to keep it straight?

 

[Texas Clodhopper]

Does the Isata have lane assist? I had a Lexus SUV with lane assist that seemed to wander.

 

[mwk]

I don’t have your type of vehicle, but do have a straight axle on my class a gasser. We can have some wondering on ours and many add a steering stabilizer which helps.
Of course not being the same vehicle it’s not a very good comparison so I used ChatGtp and entered your vehicle and issue. Here is what it said.

For your particular symptoms, I’d focus on these

1. Front-end caster — very high on my list.
Insufficient positive caster can produce exactly the feeling you’re describing: vague steering, poor return-to-center and constant corrections. A motorhome conversion can also change the loaded attitude of the chassis.

2. Front track bar / track-bar mounts.
On a heavy 4×4, even a small amount of movement here can make the coach feel like it’s wandering or being pushed sideways when the road surface changes.

3. Steering linkage and steering box.
I’d want the shop to measure actual steering free play rather than simply looking at the components and saying they appear tight.

4. Motorhome body/subframe and weight distribution.
This is especially important with your vehicle. The 5500 is designed to be heavily upfitted, and Ram specifically markets the chassis for a wide variety of upfits. The way the motorhome body is mounted and where the weight sits can have a substantial effect on handling.

5. Tire pressure and tire type.
I would not automatically run the maximum pressure molded on the tire. The coach should be weighed, ideally each axle and preferably each individual wheel position, and tire pressures set according to the actual loaded weights and tire manufacturer’s load/pressure table.

One important question

When you say it “wallow about,” do you mean the whole motorhome rocks/leans from side to side, or do you mainly mean the front end wanders left and right and you have to steer constantly to keep it straight?

I don’t have your type of vehicle, but do have a straight axle on my class a gasser. We can have some wondering on ours and many add a steering stabilizer which helps.
Of course not being the same vehicle it’s not a very good comparison so I used ChatGtp and entered your vehicle and issue. Here is what it said.

For your particular symptoms, I’d focus on these

1. Front-end caster — very high on my list.
Insufficient positive caster can produce exactly the feeling you’re describing: vague steering, poor return-to-center and constant corrections. A motorhome conversion can also change the loaded attitude of the chassis.

2. Front track bar / track-bar mounts.
On a heavy 4×4, even a small amount of movement here can make the coach feel like it’s wandering or being pushed sideways when the road surface changes.

3. Steering linkage and steering box.
I’d want the shop to measure actual steering free play rather than simply looking at the components and saying they appear tight.

4. Motorhome body/subframe and weight distribution.
This is especially important with your vehicle. The 5500 is designed to be heavily upfitted, and Ram specifically markets the chassis for a wide variety of upfits. The way the motorhome body is mounted and where the weight sits can have a substantial effect on handling.

5. Tire pressure and tire type.
I would not automatically run the maximum pressure molded on the tire. The coach should be weighed, ideally each axle and preferably each individual wheel position, and tire pressures set according to the actual loaded weights and tire manufacturer’s load/pressure table.

One important question

When you say it “wallow about,” do you mean the whole motorhome rocks/leans from side to side, or do you mainly mean the front end wanders left and right and you have to steer constantly to keep it straight?

Thanks MAC, Most of those items from AI had crossed my mind, I WILL have the alignment checked (attention to Caster) The "wallowing" phenom is more like YAW; FrontEnd and RearEend slosh back and forth while traveling straight ahead. I'm thinking steer stabilizer, maybe upgrade shocks and anti roll pieces. Nice Beard by the way...

 

[BGMAC]

Thanks MAC, Most of those items from AI had crossed my mind, I WILL have the alignment checked (attention to Caster) The "wallowing" phenom is more like YAW; FrontEnd and RearEend slosh back and forth while traveling straight ahead. I'm thinking steer stabilizer, maybe upgrade shocks and anti roll pieces. Nice Beard by the way...

Ours does the same. Many get aftermarket sway bars front and rear plus Koni shocks.

 

[mwk]

I don’t have your type of vehicle, but do have a straight axle on my class a gasser. We can have some wondering on ours and many add a steering stabilizer which helps.
Of course not being the same vehicle it’s not a very good comparison so I used ChatGtp and entered your vehicle and issue. Here is what it said.

For your particular symptoms, I’d focus on these

1. Front-end caster — very high on my list.
Insufficient positive caster can produce exactly the feeling you’re describing: vague steering, poor return-to-center and constant corrections. A motorhome conversion can also change the loaded attitude of the chassis.

2. Front track bar / track-bar mounts.
On a heavy 4×4, even a small amount of movement here can make the coach feel like it’s wandering or being pushed sideways when the road surface changes.

3. Steering linkage and steering box.
I’d want the shop to measure actual steering free play rather than simply looking at the components and saying they appear tight.

4. Motorhome body/subframe and weight distribution.
This is especially important with your vehicle. The 5500 is designed to be heavily upfitted, and Ram specifically markets the chassis for a wide variety of upfits. The way the motorhome body is mounted and where the weight sits can have a substantial effect on handling.

5. Tire pressure and tire type.
I would not automatically run the maximum pressure molded on the tire. The coach should be weighed, ideally each axle and preferably each individual wheel position, and tire pressures set according to the actual loaded weights and tire manufacturer’s load/pressure table.

One important question

When you say it “wallow about,” do you mean the whole motorhome rocks/leans from side to side, or do you mainly mean the front end wanders left and right and you have to steer constantly to keep it straight?

Thanks MAC, Most of those items from AI had crossed my mind, I WILL have the alignment checked (attention to Caster) The "wallowing" phenom is more like YAW; FrontEnd and RearEend slosh back and forth while traveling straight ahead. I'm thinking steer stabilizer, maybe upgrade shocks and anti roll pieces. Nice Beard by the way...

Does the Isata have lane assist? I had a Lexus SUV with lane assist that seemed to wander.

yes, it does. I have it turned off. Our '23 Jeep Grand Cherokee has all the drive by wire junk, and has given me serious "pucker" experiences. I have been a "driver" for over 60 years, I don't feel the manufacturer's have done anything to promote driver excellence by designing in preemptive features. thanks for the reply