weight distribution hitches - Fiberglass RV


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Old 07-05-2007, 11:15 PM   #1
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In a couple of weeks I am off to Oregon to collect our new-to-us Burro 17. Our TV is a 2007 Ford Ranger 4wd, 4.0 litre and I have a class III hitch and 7-pole harness all set. But after reading through numerous posts about WDH I'm still not clear whether I need one, or just an anti-sway set-up, or anything at all other than a 2-inch ball. Can anyone out there offer me some guidance? I've towed a fifth wheel before, and a tent trailer, but this will be my first experience with a TT and I want our trip home to be safe and uneventful (other than the good stuff). Thanks for your help .
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Old 07-06-2007, 12:11 AM   #2
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In a couple of weeks I am off to Oregon to collect our new-to-us Burro 17. Our TV is a 2007 Ford Ranger 4wd, 4.0 litre and I have a class III hitch and 7-pole harness all set. But after reading through numerous posts about WDH I'm still not clear whether I need one, or just an anti-sway set-up, or anything at all other than a 2-inch ball. Can anyone out there offer me some guidance? I've towed a fifth wheel before, and a tent trailer, but this will be my first experience with a TT and I want our trip home to be safe and uneventful (other than the good stuff). Thanks for your help .
Cheers
Ian
Could you physically tow your 17ft w/o a WDH and a anti-sway device?

YES.

Would your vehicle ride and handle better, and be safer with both.

YES.

To me, that's all I needed to know.

$250 or so total for both (if you're careful where you buy) seems a small price for even a moderate margin of safety.

Bob
BTW, weight behind the axle (on the ball) removes weight from your front axle that you steer with. Sway INCREASES the need for TV stability, which without a WDH you have given up. The combination of WDH and anti-sway help restore the stability you had before you put several hundred pounds on that ball.
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Old 07-06-2007, 12:08 PM   #3
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You could calculate the axle loads on the Ranger with and without the trailer - or just measure them - and see if there is a problem before deciding to add a solution to it.

Which Ranger are we talking about - the regular cab 6' box (112" wheelbase), regular cab 7' box (118" wheelbase), or Super Cab (126" wheelbase)? What are the hitch weight ratings for the Ranger for weight-carrying (no WD) and weight-distributing configurations? How much passenger load is expected in the Ranger's cab, and how much cargo load in the box? What are the Ranger's axle ratings and empty axle weight? What is the hitch weight of the Burro?

Sorry if it seems like a lot of questions , but since a WD system exists to shift load from the truck's rear axle to the other two axles, at least some of this information is required to get the best answer.
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Old 07-07-2007, 09:36 AM   #4
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You could calculate the axle loads on the Ranger with and without the trailer - or just measure them - and see if there is a problem before deciding to add a solution to it.

Which Ranger are we talking about - the regular cab 6' box (112" wheelbase), regular cab 7' box (118" wheelbase), or Super Cab (126" wheelbase)? What are the hitch weight ratings for the Ranger for weight-carrying (no WD) and weight-distributing configurations? How much passenger load is expected in the Ranger's cab, and how much cargo load in the box? What are the Ranger's axle ratings and empty axle weight? What is the hitch weight of the Burro?

Sorry if it seems like a lot of questions , but since a WD system exists to shift load from the truck's rear axle to the other two axles, at least some of this information is required to get the best answer.
Not sure how to answer some of this. The TV is a 126" super cab, and the tow weight limit for the stick shift is 3140 lbs, although that's a transmission limitation. The AT version is rated for 5500-plus lbs, so the suspension and braking should handle the burro's (listed) 1,800 lbs no problem. Assume that puts tongue weight between 150 and 200 but haven't measured that yet. Passenger/truck load will be around 700 lbs. Not sure about the axle rating or where to look for that, or the empty axle weight except to say payload max is 1260 lbs.
Thanks Brian and everyone for your assistance. Just want to get this right.
cheers
Ian
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Old 07-07-2007, 07:14 PM   #5
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Ian, the actual weight of your Burro 17 is likely to be closer to 2300 lbs if well equipped. The tongue weight will be significantly more than your estimates, particularly if the battery is installed on the tongue, and you have two propane bottles. You'll be in the 350lb +/- range. While I didn't actually weigh mine, I suspect it pushed 400 lbs as equipped. I used a Reese Dual Cam setup with it with a '94 Toyota extended cab, 4WD Compact Truck. It had the 3.0l V6 and an auto trans with a 3500 lb tow rating. While I had 600 lb WDH bars that worked well, 550s would probably have been even better.

With the dual-cam setup, the trailer/tow vehicle combo tracked like it was on rails. It wasn't overkill at all.

Dual Cam instaled on Burro & Toyota



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Old 07-07-2007, 09:43 PM   #6
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Not sure about the axle rating or where to look for that, or the empty axle weight except to say payload max is 1260 lbs.
Axle rating (GAWR) is on the door sticker. Here's the one on my 98 Ranger:
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Old 07-07-2007, 09:49 PM   #7
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Axle rating (GAWR) is on the door sticker. Here's the one on my 98 Ranger:
Thanks Pete. The verdict is 2710 lbs front, 2750 rear. Now if I knew what the significance of that is . . . . . not a car person, you can see.
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Old 07-07-2007, 11:32 PM   #8
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One reason why the wheelbase (126" in this case) is important is that with a longer wheelbase, the front tires have a longer lever to control the yawing (rotating around a vertical axis, as in turning) of the truck, and therefore the trailer. The Super Cab will work better than the shorter versions, and is even longer than some full-size trucks ; I would keep this in mind when considering experience with other tow vehicles.

The other reason for the importance of wheelbase is that when it is combined with the overhang (from rear axle to the back of the truck) it determines how much the trailer tongue weight tends to use the truck as a lever to pry load off of the front axle and transfer load to the rear axle. The 2007 Super Cab Ranger has (according to the Ford brochure) 44" of overhang; add another 4" to get to the closest practical ball placement, and the overhang is 38% of the wheelbase. That means that for every pound of trailer tongue weight, 38% of one pound is pried off of the front axle, so the rear axle load goes up by 1.38 pounds, and the front axle load goes down by 0.38 pounds.

If the tongue weight is 350 lb (for instance), that means that compared to the empty truck, adding the trailer would lower the front axle load (weight) by 350x38/100= 133 lb; the rear axle load would be raised by 350x1.38= 483 lb. That front axle change is about 3% of the empty truck's 4200 lb weight; I can't get too worked up about that; a similar change doesn't cause problems for my front-drive minivan.

One reason that I asked about axle capacities and cargo is that if you take the empty axle weights (which we don't know yet), add passenger weight (say split equally between front and rear) and cargo weight in the box (say directly on the rear axle), and the effect of the trailer tongue weight (calculated as above), you know how much is on each axle. The rear axle load must be within that 2750 lb limit, or you must either ditch some load and/or use a weight-distributing hitch system.

Another reason: the weight of passengers and cargo (in the truck) and the tongue weight must be keep the whole truck within it's Gross Vehicle Weight Rating (GVWR). Ford has done the math for you and says that the passengers plus cargo plus tongue weight (which together are the payload) must be no more than 1260 lb.

Finally, the owner's manual should list towing limits for both trailer hitch load (tongue weight) for "weight carrying" (no WD system) and "weight distributing" (with WD system) setups. If the tongue weight is over the weight carrying limit, then you need a WD system, regardless of the axle loads, which is a pretty direct answer to the original question. If in doubt (and even when not...) read the manual.

The Ranger is a rear-wheel-drive truck. As the axle ratings show, it is intended to carry as least as much load on the rear axle as the front, but when empty it is really front heavy. When you added everything up if it is still front-heavy, and you are within weight-carrying limits then there is no reason to use a weight-distribution system, unless you think it's needed for the sway-control side effects.
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Old 07-07-2007, 11:42 PM   #9
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...the tow weight limit for the stick shift is 3140 lbs, although that's a transmission limitation. The AT version is rated for 5500-plus lbs, so the suspension and braking should handle the burro's (listed) 1,800 lbs no problem.
I agree that the auto transmission version's ratings provide an indication of suspension capacity, but a more direct one comes from those gross axle weight ratings (GAWR). If the GAWR numbers were not available, this would be a good starting point.

The [b]braking capacity is another matter entirely. Those towing limits are based on many factors, and many assumptions, including that all operating limitations are observed. I would expect to find in the owner's manual a requirement that trailer brakes are used for any trailer over some set weight limit, regardless of engine or other truck variations. For all but full-sized trucks, that's usually only 1000 lb (the limit for my van, for instance); even the full-sized GM trucks only allow 2000 lb... and the "1800 lb" Burro will more likely be 3000 lb by the time the real trailer weight, water, propane, and cargo are accounted for.

The truck's brakes are not intended to stop the trailer, although they inevitably have to do some of that work (trailer brakes and their controls are far from ideal). Even if they could handle the whole mass of the trailer if it were carried in the pickup box (and they can't), they won't be as effective when that mass is in a trailer, because the trailer's axle weight doesn't contribute to traction for the truck's tires. The biggest imaginable brakes can still do no more than the tires can, and the tire traction is limited by the weight forcing them into contact with the road.
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Old 07-08-2007, 06:59 PM   #10
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What the Gross Axle Weight Restriction (GAWR) means is that is the design limit of the weight that axle is intended to carry.

As a somewhat practical matter, you take the truck with a full tank of fuel to a scale and weigh each of the axles. If you have a GAWR of 1000 lbs and a scale weight of 700 lbs, you can carry up to 300 lbs (1000-700) before hitting that restriction.

Actually, however, it's more complicated than that because unless that 300 lbs is *exactly* over the axle, it will have a seesaw effect on the *other* axle.

That's where GVWR (also on the door sticker) comes in, a restriction on the *total* weight of the truck (somewhat less than the total of the GAWRs to make some allowance for the seesaw effect). Take the scale weights of both axles added together, subtract that from the GVWR and the remainder is called 'payload', which would include everything that wasn't in the truck when you weighed it, including passenger, hitch receiver (if not previously mounted) AND tongue weight of the trailer.

Next comes GCWR, which will be found in the Owner's Manual if not on the door sticker (Ford puts it in the OM). This is the limit on the total of the truck, trailer, hitch, cargo/passengers in the truck and cargo in the trailer.

Usually, the vehicle's towing capacity is derived by subtracting the expected weight of the truck and cargo from the GCWR. This means that if you have loaded the truck right up to a GAWR or GVWR, likely you have intruded on your towing capacity.

Finally, Ford OM's carry this note "For high altitude operation, reduce GCW by 2% per 300 meters
(1 000 ft.) elevation." Since the truck is usually not carrying stuf which can be left behind, this reduction typically means a reduction in trailer weight. I believe this is a large part of why experienced RVers like to apply the 75% Rule, where one should not have a trailer weight that exceeds 75% of the towing capacity.

The whole GXXX scheme is kind of a pyramid built on the axle capacities (which also include the tire and wheel capacities, so if you put less load-capable tires or wheels on a truck or trailer, you must reduce capacities; putting greater load-bearing stuf on does NOT increase capacity because none of these things operate alone -- Like a chain, the weakest link sets the limit, not the strongest).
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Old 07-08-2007, 09:03 PM   #11
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Usually, the vehicle's towing capacity is derived by subtracting the expected weight of the truck and cargo from the GCWR. This means that if you have loaded the truck right up to a GAWR or GVWR, likely you have intruded on your towing capacity.
For many vehicles, including essentially all pickup trucks, there is zero cargo allowance in the manufacturer's towing capacity calculation (just a driver allowance), so if you so much as pack a lunch you're cutting into the towing capacity. For passenger vehicles there is usually a lower towing capacity published which still allows for cargo; for instance, my Sienna can still handle several hundred pounds of cargo in combination with the 3500 lb allowed trailer.

For a pickup, if you know the GCWR, it is easiest to start from it, subtract the truck, passengers, and cargo and see if there enough left for the trailer.

According to Ford's Towing Guide for the Ranger, the GCWR is 7000 lb with a manual transmission (and 9500 lb for the automatic). They show a trailer capacity of 3080 lb for a 4x4 SuperCab manual, so that truck with a driver must weigh about 3920 lb - I really don't think that allows for any cargo.

So the stick-shift Ranger is going to be marginal for a loaded 17' Burro, from a drivetrain point of view, so it would be good to be careful to avoid excessive clutch slipping (the clutch is likely the weak link, and the reason for the disadvantage compared to the automatic). Axle capacities are another matter entirely, in which the manual is not at any disadvantage, so the WD or no WD question is still open.
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Old 07-08-2007, 09:10 PM   #12
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...Finally, the owner's manual should list [b]towing limits for both trailer hitch load (tongue weight) for "weight carrying" (no WD system) and "weight distributing" (with WD system) setups. If the tongue weight is over the weight carrying limit, then you need a WD system, regardless of the axle loads, which is a pretty direct answer to the original question.
... and the towing guide (linked above) says:
weight-carrying maximum: 3500 lb trailer and [b]350 lb hitch weight
weight-distributing maximum: 6000 lb trailer and 600 lb hitch weight

.. not that any Ranger is actually allowed tow a 6000 lb trailer! Oh well, the hitch can handle it.

The weight-carrying limits are the same as for my Sienna. I run about 300 lb hitch weight with a B1700 (also a 17' widebody), and do not use a WD system. Casitas of the same length and similar weight tend to have much higher hitch weight, and thus would require WD on a Ranger, regardless of axle loads. The Burro?
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Old 07-08-2007, 11:01 PM   #13
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For many vehicles, including essentially all pickup trucks, there is zero cargo allowance in the manufacturer's towing capacity calculation (just a driver allowance), so if you so much as pack a lunch you're cutting into the towing capacity. For passenger vehicles there is usually a lower towing capacity published which still allows for cargo; for instance, my Sienna can still handle several hundred pounds of cargo in combination with the 3500 lb allowed trailer.

For a pickup, if you know the GCWR, it is easiest to start from it, subtract the truck, passengers, and cargo and see if there enough left for the trailer.
I believe you are right about this; I shouldn't have used cargo, but I also had in mind that some vehicles reportedly do have an allowance for cargo that was computed into the towing capacity.

The need for WDH on a particular vehicle can be quickly determined by looking at the specs on the factory bumper (if set up for a hitch ball, like my '98 Ranger is) or the specs on the hitch receiver. If the trailer weight or tongue weight is going to exceed the non-WDH spec, then a WDH is needed. Of course, not all vehicles are capable of using a WDH due to body capabilities. My Ranger's OM does not address WDH; AFAIK, it is implied by the bumper/receiver specs.

One of the Rangers on the Ford URL has a tow capacity of 6,000 lbs, so the hitch receiver could be used to its max capacity (less the weight of the hitch receiver, WDH gear and tongue weight. But, given the presumption that the 6,000 lb tow capacity is with a cargo-less, passenger-less truck, that means the axle weight of the trailer could only be 5400 minus the receiver weight (6000-600TW=5400) and that presumes the WDH is part of the TW... All the more reason for not towing at full 'paper' capacity.
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Old 07-09-2007, 12:31 AM   #14
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And I thought I was confused before . Does this mean yes, or no to a wdh?
cheers
Ian
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