Clearance between truck and 5er?

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elm_tx

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I posted a question on here a week or so ago concerning the 5er bouncing up and down Real bad when I first picked it up. It was empty. The general response seemed to be that it was not balanced, which was true, the front was higher then the rear.

I called the folks that put the hitch in the bed to check on how tight to torque the bolts when I lowered the hitch, they were adamant that I bring it in and let them do it for free. When I got there they tried to talk me out of lowering it, saying that if the truck goes thru a dip there is a good chance of the 5er impacting the top edge of the truck bed.

How much clearance do I need between the two while sitting level, so as to reduce the likely hood of this happening? Also when I talked about the bouncing effect, he said it was do to my having a short bed truck. Does that sound right? It's  short bed crew cab 06 chevy.

As usual, I really appreciate everyones feedback. Below is a link that shows the truck and 5er, one of the last pics shows the truck & 5er sitting on the road with the front gear up (all the others it was down as I had to park it over night)

http://share.shutterfly.com/action/welcome?sid=0AauWrVq4aMmLjo
 

Bob Buchanan

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elm_tx said:
How much clearance do I need between the two while sitting level, so as to reduce the likely hood of this happening? Also when I talked about the bouncing effect, he said it was do to my having a short bed truck. Does that sound right? It's? short bed crew cab 06 chevy.

When I pulled a 5thW, I was told 6 inches clearance by several hitch outfits. Another said it should be "at least" the width of your hand including the thumb. I went for the 6 inches as my hand wasn't that wide. I got so I could do the adjustments myself both in adjustment the king pin or the hitch. Sometimes one will give more or less of an adjustment that the other.

Tho I am not the expert in this area, would image the bouncing has more to do with wheel base vs. the bed length. Seems the effect of the bed length would have more to do with ability to turn with hitting the cab.
 

Gary RV_Wizard

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Bed length per se has no effect on bouncing because the hitch is over the axle regardless of bed length.  However, as Bob says, a short bed truck will have a shorter wheel base than an otherwise identical long bed. But any extended cab or crew cab truck will have plenty of wheel base length, regardless of bed size. Only in the case of a regular cab short bed will the wheel base be short enough to frequently stimulate a noticeble pitching motion.

Clearance over the bed sides is rarely an issue. A hand breadth is the rule of thumb but that often is not achievable with today's tall trucks (especially those with 4 WD, which are designed with more road clearance). If you have 4 WD but seldom go really off-road, you might consider having the truck lowered to the height more common on a 2WD model.  I towed a big fiver all over creation with only about 4 inches clearance on an F250 Superduty and never touched the side rails. And that was with a "rocking" type hitch too, that allows considerable side-to-side tilt. I won't say its impossible to hit the side rails, but it is really not a major concern in most cases.

Note that having the hitch set high raises only the forward part of the trailer (the king pin area). It is still probably close to the side rails back by the tail gate, so if you are going to hit the sides it will still probably hit near the back even though the hitch is high. 

What did the hitch shop say about getting the trailer level? Or didn't they care about that?

Another option is to raise the trailer by increasing the height at the trailer axles, sometimes called "flipping" the axle. The downside of this is that it raises the center of gravity of the trailer and makes it more prone to leaning or even tipping in an emergency swerve.
 

Carl L

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Gary,

Take a look again at that 5er of theirs.  That rascal has a helluva overhang behind the axles.  I wonder if there is enough weight on the king pin.  Should be 20-25% for a typical 5er if I remember correctly.  Maybe he should check on the pin weight.    Shifting load forward may help his situation.
 

elm_tx

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They didn't seem all that concerned about getting it level. His big thing was that I shouldn't be trying to balance it empty. He felt I should load it up and take a trip and see how it felt then. But that thing was bouncing up and down sooo much I'd rather sell it then pull it like that.

I went and hooked up a short while ago and drove around, I've got a good 6" of clearence and the bouncing effect is greatly diminished. I can still feel it to an extent but the truck is not hopping 6+ inches like it did originally.  Based on what y'all are saying, it sounds like I'm fairly safe clearence wise. Thanks!!!

Where would I take it to get the pin weight checked? Would this be something Camping World would help with?

Thanks y'all!!!
 

Carl L

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I have taken a look at the KZ brochure on your trailer.? For the 36 footers, they list an unladen trailer weight of 12,000 lbs. and a hitch weight of 2100 lbs.? ?That is an unladen hitch weight of only 17.5% of trailer weight!? ?Now I am a TT type not a 5er but that seems awfully light -- most references I have say that 25% is the target weight.?

Question:? Where is your freshwater tank?? If it is forward of the axles, fill it for travel.? ?55 gallons will help a bit depending on the lever arm.? ?In any case, bias your loading forward.

Checking hitch weight can be done at a public scale in your neck of the woods.? Since I do not pull a 5er I will leave it to another member here to give you the exact procedure.? Generally speaking it involves moving the trailer on the scale with all the truck wheels off the scale.? Take that weight - that weight is your trailer weight less the hitch weight which bears on your truck.? Then unhitch the trailer from the truck and take that weight -- this weight is the weight of your trailer.? ? Subtract the first weight from the second weight -- the remainder is your hitch weight.? That weight should be around 25% of your trailer's weight.?

For directly checking the hitch weight, there is the Sherline Gauge.? ?See it clicking on HERE  You would want the 0-5000 model.  I use one myself to keep me honest on packing.  By the way, the Sherline trailering PDF manual is worth downloading and reading.
 

Bill_Frisbee

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I am convinced that the issue of pin weight is being driven by the capacity of existing pick-ups to tow big 5ers. A 12,000 lb 5er should have 3,000 lbs on the pin according to the 25% rule. I am not aware of any pick-up (normally loaded with passengers, fuel, clothes, and trailer hitch) other than a one-ton dually that is legally capable of carrying that much pin weight. My Montana has an "out the factory door" weight of 11,650 lbs and an "out the factory door" pin weight of 1,975 lbs - less than 17%. I do everything I possibly can to keep the amount of "stuff" we haul around in the 5er at an absolute minumum and have had no towing problems of any kind. The 5er is steady as a rock going down the highway. In my opinion, one reason for this happy situation is that (in our particular model) the weight not being carried on the pin is largely centered directly over the axles of the RV.

Bill
 

Carl L

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Well Bill, be that as it may, Elm-tx seems to have an actual problem here.  Your 5er pulls like a champ.  His does not.  Load shifting is a cheap cure to investigate.  The actual weights of any trailer, or motorhome for the matter, is a good piece of info to have about your trailer and may point to a cure for stability problems.

And, yes, it duallies do seem to be popular with folks who pull big fivers.  Medium duty trucks seem to have a small but growing popularity also.   
 

Gary RV_Wizard

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I think 25% pin weight is on the high side, Carl.  The range is probably something like 18-25% with somewhere around 20% being typical.  As Bill says, not many pick-ups could actually handle a 25% pin weight, even on a 30 foot fiver.

I had not looked at the pictures before - that trailer really does have a huge rear overhang!  It really should have a triple axle, but that might interfere with that big side door. Is that a ramp like a toy hauler?  Is this one of the Moto-mover models that New horizons makes?  If it bounces now, I can't imagine what would happen if a ATV or other heavy load was put in the back of that thing! Yikes!  And if the water tanks are behind the axles... wow!

The out-of-level condition looks about normal for a 4x4 pick-up, which is usually taller than a 4x2. I don't think the out-of-level  is real bad and I would not expect it to create the severe problem that elm-tx describes. Getting it level should alleviate the bounce some, though.

An air ride hitch might take some of the violence out of the bounce. The trailer still pitches up and down but the air bag(s) in the hitch absorb the shock.

I'm reluctant to suggest much more in the way of solutions without having a chance to drive the rig.  It looks unstable to me.

 

Carl L

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I'll defer to your experience on 5ers.  I was just quoting Bill Estes on the subject ofm hitch weight percentages.  However, ain't that rear overhang a doozy!  It looks like a big slide is part of the rear overhang too.  Makes one kinda wonder if the mfr. based his weights on calculations not weighings.  Elm-tx needs some real numbers here.  A trip to a public scale may clarify a few things.

However, there may be a saving grace.  It looks like the fresh tank is well ahead of the axles .  If so, and if it is 55 gallons as spec sheets say, then that is a cheap way to weight up the hitch with 440 lbs of weight ahead of the CG of the trailer.  Work or not, a full water tank is cheap enough for a try. 

A shock kit for the trailer might be another approach, but not nearly as cheap as a water cure.  ;D
 

Gary RV_Wizard

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I'd like to see the road elm-tx drove over before deciding how big the problem is.  Certain road conditins will set up a pitching motion and with that much rear overhang it might  happen more easily than on a typical fiver.

Elm-tx: Ya gotta get that thing weighed, with axle weights for each of the  truck axles and the trailer axles as a combined pair. You need the truck rear axle weights with and without the trailer hitched to determine the actual pin weight. Usually we say to do this loaded as you would be for a trip, including any people who usually ride in the truck, but in this case you could go "abre" if you want to for the initial weigh in. You can do this at any public scale - many truck stops have them, some moving companies, and grain elevators and feed mills often have them.  Google Cat scales to find locations of CAT public scales.
 

elm_tx

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Houston, Tx
The rear does not open, there are two recliners back there. The big slide by the door has an entertainment center / computer nook in it. The opposing slide has the sofa, table and chairs in it. The tanks are between the hitch and the two axles. 

By dropping the hitch one notch it really helped to settle down the bouncing motion. But it's still not totally smooth, which considering my lack of experience towing anything, maybe this is the way it's supposed to feel.

I will find a place locally to get it the individual weights as y'all suggest. I'll let y'all know what I find. 

If you're familiar with Houston, I was going East on 290 between Waller and Houston. Also experienced it going down the feeder roads, and they are in pretty good shape.

Thanks again for the input guys!!!
 

Carl L

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I'd like to see the road elm-tx drove over before deciding how big the problem is.  Certain road conditins will set up a pitching motion and with that much rear overhang it might  happen more easily than on a typical fiver.

Yeah, older concrete freeways can set up that sort of thing no matter how well balanced the unit.  The I 405 near me does it just fine.
If it occurred on a asphalt road or a reasonably decent road, he has a real problem.   

I would say, that:  (1) he tries the water trick, it is quick and cheap;  (2) he gets his unit weighed, to see if weights are an issue;  (3) with weights and experience in hand, he goes and has group therapy with his dealer's service boss;  (4) he comes back here and tells us what is really wrong so we learn something.  ;D   
 
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