W22 steering wander

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:

norisezp wrote:
OKay I got the weights on a CAT scale with the unit partly loaded with leftovers from a trip. They are Steerable = 6560, Drive Axle = 13180, GVW = 19740. This does not really square up with the weights on the Federal Certification Tag of S=8000, DA=14500, GVWR=22000. Anybody got any ideas of the explanation? I mean, I could see it being more, but less? Or, are the FCT numbers maxima?

On further thought, before you make any changes to your MH, it would probably be best if you weighed it again, but, do it after you load it similar to when you drive it on trips. Your partially loaded weights (which you listed above) may throw your "true" weight and balance off.

For example. If your fresh water tank is empty, it adds zero weight. When full, if it holds 80 gallons, you just added 80 x 8.2 = 656 lbs. to your max gross weight. How it distributes depends on where the tank is located in your MH. The same occurs for fuel, black/grey waste, propane, food, and, your personal items.

Chum lee

Rereading the requirements for the FCT, I see that the weights are loaded, not unloaded, as I thought. So, in that way, they are "maxima" as I asked. This point is clear.

I also think I see a way to use these values to determine what a target minimum front weight could be, by using proportions as follows:

Target MFW = Measured Rear Weight * FCT Front Weight / FCT Rear Weight

So, in this case,

Target MFW = 13180 * 8000 / 14500= 7272, about 712 more than the measured 6560


Right?

Correct.

Your handling will improve if your front axle weight moves from current 6560 closer to front axle GAWR of 8000.

Moving weight forward will help that, particularly significant for weight moved from behind the rear axle.

Ideal weight distribution would be to have each axle loaded to the same percent of its GAWR.

norisezp wrote:
OKay I got the weights on a CAT scale with the unit partly loaded with leftovers from a trip. They are Steerable = 6560, Drive Axle = 13180, GVW = 19740. This does not really square up with the weights on the Federal Certification Tag of S=8000, DA=14500, GVWR=22000. Anybody got any ideas of the explanation? I mean, I could see it being more, but less? Or, are the FCT numbers maxima?

The FCT numbers are the GAWRs and the GVWR -- the maximum rated weights for the axles and vehicle as a whole. Your actual weights should be lower than these numbers. The RV information tag (typically found inside a cabinet somewhere) should give you the (at least hypothetical) empty weight of the RV, the capacity of the various tanks and their weights when full, and some indication of the payload capacity based on that information. The exact format and numbers and definitions used has varied over the years a bit.

s N s wrote:

wolfe10 wrote:
OK, what can you move FORWARD!

.

X 1 I totally agree with the above post.

Agree also. Moving weight forward will help with steering caster angle which should improve your directional stability. Try that first, then change your tire pressures, (also check for irregular tire wear) then, if no help, have your alignment checked/adjusted. Make sure everything is adjusted properly before you start installing band aids.

Start with the attitude: "When everything is loaded correctly, the tire pressures are correct, and, the alignment is correct, the vehicle will drive/ride properly." Not: "Let's throw some parts at this problem." (unless you have obvious wear issues or bent/damaged parts)

Chum lee

wolfe10 wrote:
OK, what can you move FORWARD!

With those weights, there is no way is should handle/ride well.

X 1 I totally agree with the above post.

I guess I don't understand your question. The FCT weights are all more than what your actual weights are not less.

OK, what can you move FORWARD!

With those weights, there is no way is should handle/ride well.

OKay I got the weights on a CAT scale with the unit partly loaded with leftovers from a trip. They are Steerable = 6560, Drive Axle = 13180, GVW = 19740. This does not really square up with the weights on the Federal Certification Tag of S=8000, DA=14500, GVWR=22000. Anybody got any ideas of the explanation? I mean, I could see it being more, but less? Or, are the FCT numbers maxima?

s N s wrote:
Ours too is bone stock and I have no problem with any wander. I keep our tires inflated to 95 all around but that may be different for everyone as far as weight goes. Also as mentioned be sure not to overload the rear and take to much weight off the front axle within reason. Another trick if you're are new to driving a motor home is to look further down the road rather than looking down right in front of you. It for some reason gives you a better perception of keeping the rig straight and narrow down the road. Good luck and hope the issue get's resolved.

Along with this, make smaller corrections and expect the vehicle to take longer to react. A long wheelbase vehicle simply reacts more slowly than a shorter wheelbase vehicle, and if you're used to the latter it is very easy to overcorrect...and then have to (over-)correct again, and again, and....

Keeping your focus further down the road does help here, I suspect because you're not responding to every little blip back and forth but rather to your overall trajectory. Figuring out where the lane edges should be in relation to the dash to be in the proper position in the lane will help you keep your eyes down the road (and rely on peripheral vision to stay centered) rather than having to constantly look close up. On my motorhome, it works out that the left side of the lane needs to appear to be going straight towards or through the dashboard vent grille on the left of the steering wheel, which sure felt wrong at first even though it's demonstrably correct.