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davemilster's avatar
davemilster
Explorer
Sep 07, 2017

2013 Fleetwood Excursion Freightliner XCS chassis

Hi All,
I have the subject RV with 24XXX miles. It's a diesel pusher. It has NEW tires all around (age replacement) and their all inflated to 120lbs. I bought it with 10K miles on it. Since new, I've been bothered by a handling issue and have searched on line for solutions and found nothing per se' appropriate to my issue. The new tires have not changed handling either. While cruising down the road I find the coach when it LEANS to either side due to any causes, such as cross winds, tilted pavement, other trucks, etc, the back end swings out toward the side to which it's leaning pushing the nose of the coach the opposite direction. When you enter into a sweeping turn on the highway, you first turn the wheel to start into the turn, then the coach leans a bit which causes the rear suspension to "steer" a bit and then you have to correct the steering wheel back close to neutral. The sensation is a bit like you're driving on ice and have to make no sudden movements or you feel like you'll spin out of control. Not very calming on a long drive!

Now I've worked on sport handling cars and dealt with "OVERSTEER", but this is a bit different. In a car, the harder you corner, the more oversteer you have as the body leans. This COACH though doesn't seem to lean any farther (or if it does, no further oversteer occurs) and a hard corner produces no more oversteer than a sweeping turn.

On a car, I'd just add or increase the size of the FRONT stabilizer bar to minimize oversteer, or use urethane link bushings vs rubber, but this is different.

I've also noticed when going over a speed bump slowly at an angle, the front suspension seems to have NO side to side leaning (or stabilizer bar effect), where the rear over the same speed bump on an angle tilts the coach dramatically. I've looked underneath and see no stabilizer bar on EITHER end of this coach.
SO here are the questions:
Who are the experts in Freightliner XC/XCS chassis tuning?
Who has dealt with this overteer/body lean on an XCS (SHORT) chassis? It's 35ft long vs the typical 38-40 on an XC chassis.

4 Replies

  • "davemilster".....You don't say what brand tires you installed. You also said they were replaced due to age.....4 years? Is the coach new to you or are you the original owner. Trying to get some info as to when this started and with what tires.

    With that said, I owned a 1990 Fleetwood Jamboree that came new with Michelin tires. We owned it for 14 years, so there was a tire replacement along the way. Being young and not wealthy, I replaced the tires with Daytons, which I believe were an off brand of Goodyear.

    When we went on our first trip, I found that on sweeping turns on the freeway, the coach just wanted to roll and lean like it was still turning after I had stopped. It was very disconcerting and certainly didn't feel safe. It sounds like yours is doing what mine did.

    Back then, I didn't no to check the sidewall plies or load rating, just trusted that America's Tire Company was selling me the right tires. I took them back and paid the difference to have Michelins put back on. Problem solved.

    So my point......I would look to see if the new tires are sufficient for the load in terms of ply rating both tread and sidewalls. If they're a cheap off brand, they may just not perform well.
  • Ivylog's avatar
    Ivylog
    Explorer III
    Over inflated rear tires will make for squirrely handling, not better handling. New tires can take a 1000 miles to stop doing what you describe. Go to a truck stop with a Cat scale and get your axle weights and set tire pressures accordingly.
  • The Freightliner information states to run the fronts at 120 lbs and the rears at 105 lbs. At these settings, the oversteer was significantly worse. So that's how I arrived at 120 for the rears.
    I'm not sure where to go to get the corner's weighed. Is that at a Freightliner service center? A Truck Stop? The RV repair places by us have nothing like that.
  • First thing to do is get your coach weighed at each corner if possible, then go to the tire inflation chart and adjust your tire pressers accordingly. Typically what happens is the service centers will usually fill tires to the max sidewall pressure which will give you the symptoms you describe. 120# sounds too high unless the actual weight and chart gives you that #