Constantly adjusting steering wheel to stay straight.

[F53Challenge]

Hi Folks, hoping to gain some education. I have a 2011 Itasca Sunstar 26P, (28K miles) sitting on a 16k gvwr F53 chassis with only a 158" wheelbase. My overhang is 115" so 72%. So perhaps a tail wagging the Dog issue. I am hoping to find a remedy if so, other than trading it in. When driving I am constantly having to steer back to the center of my lane. Center lane, no wind, no trucks passing. I think the previous owner may have been fighting this same issue. I bought the coach with the following already installed, Kelderman Ford F-53 Chassis 2-Stage front and rear air suspension, Koni Shocks, Roadmaster rear sway bar, SuperSteer rear trac bar, SafeTPlus Steering Control, Front trac bar is not labeled. CHF has been done front and rear. 6 new Michelin tires. I have been chasing the handling issue for some time with various alignment shops that say they know MH chassis and handling. No worn parts (drag link, tie rod ends, steering box, king pins, wheel bearings etc,) have been identified. I had one of the shops add shims to adjust the caster to 5 degree positive. I have played with airbag pressure and tire pressure's without benefit. One shop that weighed the MH came up with F= 5,457lbs / R=10,651lbs so 51% on front axle. I considered I'm just getting old and not accustomed to sitting over the steering tires, however the last alignment tech told his boss, I do not know how this customer keeps this on the road. I am very much interested on input from those that have some experience with the short wheel base.
When I bought the coach, I was thinking of enjoying the golden years, not studying to become a physics expert. Thanks in advance.

[wingnuts]

If it's that bad something is wrong, I was gonna say maybe just the crown in the road may be causing it, but sounds like this issue is all the time

If all the front end parts look good I would start looking at the rear. ..if your rear end is askew even a few degrees it will pull in that direction. ..


Was it the same with the tire's you took off.?

[LJowdy]

As you've figured out, there's not enough weight on the front axle. You said you have air bags and have tired adjusting air pressure. Have you increased the the pressure in the rear and lowered the air pressure in the front? Another trick is to increase the caster angle on the front tires. I'd also make sure that you have a full alignment done (front and rear)

Aside from that, provided the alignment is correct I seriously doubt you'll solve the problem short of adding weight to the front end.

[F53Challenge]

It does not pull just left or just right. The previous owner installed the new tires.

[F53Challenge]

What percentage of the rear axle weight should the front be carrying? I have lowered the front air bag pressure with the rear increased and did not notice a difference. Of course when doing that one decreases the positive caster. I had the caster set to 5 degrees positive. Do you have some experience that would point to something other than 5 degrees positive?

[Mr_D]

Well, it won't help your handling problem but your front axle is not at 51%, it's about 33%. I didn't run the figures though.

[vsheetz]

Usually adding a rear track bar nearly eliminates this issue. But I see you already have one - plus every other aftermarket add-on... Typically the rear track bar, CHF, and SafeyTplus will provide relief and a decent handling coach. I'm wondering if a negative interaction of two or more of the aftermarket add-ons.

[F53Challenge]

Originally Posted by F53Challenge

Hi Folks, hoping to gain some education. I have a 2011 Itasca Sunstar 26P, (28K miles) sitting on a 16k gvwr F53 chassis with only a 158" wheelbase. My overhang is 115" so 72%. So perhaps a tail wagging the Dog issue. I am hoping to find a remedy if so, other than trading it in. When driving I am constantly having to steer back to the center of my lane. Center lane, no wind, no trucks passing. I think the previous owner may have been fighting this same issue. I bought the coach with the following already installed, Kelderman Ford F-53 Chassis 2-Stage front and rear air suspension, Koni Shocks, Roadmaster rear sway bar, SuperSteer rear trac bar, SafeTPlus Steering Control, Front trac bar is not labeled. CHF has been done front and rear. 6 new Michelin tires. I have been chasing the handling issue for some time with various alignment shops that say they know MH chassis and handling. No worn parts (drag link, tie rod ends, steering box, king pins, wheel bearings etc,) have been identified. I had one of the shops add shims to adjust the caster to 5 degree positive. I have played with airbag pressure and tire pressure's without benefit. One shop that weighed the MH came up with F= 5,457lbs / R=10,651lbs so 51% of rear axle weight is on the front axle. I considered I'm just getting old and not accustomed to sitting over the steering tires, however the last alignment tech told his boss, I do not know how this customer keeps this on the road. I am very much interested on input from those that have some experience with the short wheel base.
When I bought the coach, I was thinking of enjoying the golden years, not studying to become a physics expert. Thanks in advance.

Correction, 51% of rear axle weight is on the front axle.

[LJowdy]

It looks to me that roughly 30% of the combined weight is on the front axle.

Lowering the front end usually changes the camber, not the caster.
5 degree's of caster is a lot, I wouldn't add any more, besides, I doubt you have any caster adjustment left in the stock system. Remember, camber is how far the top of the tire leans in or out. Caster is defined as the angle created by the steering pivot point from the front to back of the vehicle. In other words, caster is best shown as the front wheel on a shopping cart. Look at the center of the wheel in comparison to the rear wheels on the cart. Caster keeps the front wheels rolling straight.

[wingnuts]

Originally Posted by F53Challenge

It does not pull just left or just right. The previous owner installed the new tires.

I see now ,sorry I read it wrong. ..does indeed sound like a weight issue ...

Is there any play in your steering wheel. ..?

[F53Challenge]

Originally Posted by LJowdy

It looks to me that roughly 30% of the combined weight is on the front axle.

Lowering the front end usually changes the camber, not the caster.
5 degree's of caster is a lot, I wouldn't add any more, besides, I doubt you have any caster adjustment left in the stock system. Remember, camber is how far the top of the tire leans in or out. Caster is defined as the angle created by the steering pivot point from the front to back of the vehicle. In other words, caster is best shown as the front wheel on a shopping cart. Look at the center of the wheel in comparison to the rear wheels on the cart. Caster keeps the front wheels rolling straight.

I agree, roughly 30% of the combined weight is on the front axle and that a proper caster setting helps the front wheels to roll straight. The last alignment shop showed me a printout of my settings before they added the shims to attain a 5 degree positive caster measurement, then the printout after adding the 5 degree and then a printout once they dumped the air in the front airbags (they dumped the air out of frustration with the handling). When they dumped the air, the 5 degree positive caster reverted to left 3.1 positive and right 2.9 positive. Ford spec is 3.88 - 5.38. I appreciate everyone's contributions.

[F53Challenge]

Originally Posted by wingnuts

I see now ,sorry I read it wrong. ..does indeed sound like a weight issue ...

Is there any play in your steering wheel. ..?

I held onto the pitman arm with a large set of channel lock pliers and with the engine running had my brother slightly move the steering wheel, I did not pick up any play although when drive that is the impression I get, some play between the steering wheel and the road. I am now wondering if the steering box is adjusted too tight and I need more weight in the front.

[Bob Hyatt]

Originally Posted by F53Challenge

Hi Folks, hoping to gain some education. I have a 2011 Itasca Sunstar 26P, (28K miles) sitting on a 16k gvwr F53 chassis with only a 158" wheelbase. My overhang is 115" so 72%. So perhaps a tail wagging the Dog issue. I am hoping to find a remedy if so, other than trading it in. When driving I am constantly having to steer back to the center of my lane. Center lane, no wind, no trucks passing. I think the previous owner may have been fighting this same issue. I bought the coach with the following already installed, Kelderman Ford F-53 Chassis 2-Stage front and rear air suspension, Koni Shocks, Roadmaster rear sway bar, SuperSteer rear trac bar, SafeTPlus Steering Control, Front trac bar is not labeled. CHF has been done front and rear. 6 new Michelin tires. I have been chasing the handling issue for some time with various alignment shops that say they know MH chassis and handling. No worn parts (drag link, tie rod ends, steering box, king pins, wheel bearings etc,) have been identified. I had one of the shops add shims to adjust the caster to 5 degree positive. I have played with airbag pressure and tire pressure's without benefit. One shop that weighed the MH came up with F= 5,457lbs / R=10,651lbs so 51% on front axle. I considered I'm just getting old and not accustomed to sitting over the steering tires, however the last alignment tech told his boss, I do not know how this customer keeps this on the road. I am very much interested on input from those that have some experience with the short wheel base.
When I bought the coach, I was thinking of enjoying the golden years, not studying to become a physics expert. Thanks in advance.

Unfortunately, you have really bad chassis geometry. The standard measurement is to take the wheelbase, divide by overall coach length. If that is < .50 it is going to be undriveable. Yours is right at .50 which is on the bad end of the scale. Most consider .52-.53 as acceptable, higher is better. For my 32sa, the coach is 34.25' long, wheelbase is 228", which gives 0.554. The lower that number, the bigger the "tail" you have wagging you around. Mine also came with Sumo springs, and it drives just fine. We drove a couple of Thors and a Jayco that really liked to "gallop" (rock for-to-aft) on any bump on the interstate. And trucks really pushed them from side to side.

That short wheelbase is killing you. You can go to sifffer sway bars, stiffer springs and shocks, add Sumo springs or the newer liquid springs. And you will end up with something that drives better, but rides significantly rougher... Just is what it is...

[Waiter21]

You mentioned your front end caster... What was the toe-in??? A toe out or zero toe in will cause what seems like instability in the front end....