Weight Distribution Hitch Question

[jejeosborne]

Exactly, WD can help reduce rear axle loads by adding weight to the front axle, but it cannot change the GCWR or the vehicle axle limits.


I posted several links to Putman and Reese hitches which are rated for the truck's full load. I think Diamondpilot is the member who you are thinking of with one on his Tundra. Those hitches (as you say) do not change the vehicle ratings, but do allow you to haul a heavier trailer as long as you stay withing the manufacture's axle/vehicle weight ratings.

Aaron Z

I have been a part of many of these discussions. I have seen what Diamondpilot has posted in the past. I usually am on the same side of the arguement with Diamondpilot (high five) but disagree with putting on a heavier hitch to avoid using a WD hitch for the reasons I have stated. In addidtion, who has tested the truck frame to be strong enough for these higher loads?

This is sort of true and sort of not true. When some people say the "tow capacity of the vehicle," they are referring to things like suspension, brakes, frame, axle rating, and so forth. They are referring to the vehicle and not the hitch, ball, and so forth. They think of those as two separate systems. From that perspective, adding a WD system does not change the tow capacity of the vehicle. Other people, when referring to the "tow capacity of the vehicle," are referring to everything attached to the vehicle, short of the trailer. From that perspective, the WD system may increase the tow capacity of the vehicle, if it was the hitch's weight rating that was the limiting factor. In other words, if your vehicle (with factory hitch) has a tow rating of 5000 lbs without a WD system and a 10000 lb rating with a WD system, then adding a WD system could be said to increase the tow rating of the vehicle. But I know for my truck, the specs say the truck itself is rated for 13k, but the hitch is only rated for 10k (with WD). So I would say that with or without a WD system, my truck is rated for 13k, but I can only tow up to 10k (with a WD system), and with my current trailer, I can only tow up to 7k, because it's a 7k trailer.



They usually don't, and I don't know why. Probably money. There are a few exceptions. A regular poster on TBN (sorry--don't remember who) talks about his Tundra, which has a frame-integral hitch that can tow the truck's full 10k weight without a WD system. But most factory hitches require a WD system to achieve anything close to the truck's full rated capacity. And it's not "other safety reasons," because you can swap the factory hitch with an aftermarket one that equals or exceeds the truck's towing capacity without a WD system.

Joshuabadrwell, remember me on this post?: http://www.tractorbynet.com/forums/trailers-transportation/244387-axle-location-question-3.html
I am fully aware of towing guidelines. I see that you are correctly posting many good things since this eye opening experience that I helped you with. I am just pointing out that the towing capacity of any rig is equal to the weakest link of the chain. If you have a F450 pulling a load with an 1 7/8" ball rated at 3500 lbs, the towing capacity of that setup is 3500 lbs even though every other limit is much higher in the equation.

 

[joshuabardwell]

In addidtion, who has tested the truck frame to be strong enough for these higher loads?

Presumably the manufacturer of the hitch, no? When I buy a hitch, I buy one specifically for my make/model of truck. Presumably its weight rating is based on its load-carrying capability on that specific truck. If the truck's frame was going to be damaged by the increased weight of the hitch, it doesn't seem like the hitch manufacturer would be in business very long.

I am just pointing out that the towing capacity of any rig is equal to the weakest link of the chain. If you have a F450 pulling a load with an 1 7/8" ball rated at 3500 lbs, the towing capacity of that setup is 3500 lbs even though every other limit is much higher in the equation.

100% agree.

 

[jejeosborne]

Presumably the manufacturer of the hitch, no? When I buy a hitch, I buy one specifically for my make/model of truck. Presumably its weight rating is based on its load-carrying capability on that specific truck. If the truck's frame was going to be damaged by the increased weight of the hitch, it doesn't seem like the hitch manufacturer would be in business very long.

I really doubt this is the case. They are probably testing the hitches in a solid rig for failure rates. Are you saying it is safe to pull these large loads using a 3/4 ton pickup without a WD setup even after all the discussion of distributing some of the weight to the front tires of the tow vehicle?

 

[aczlan]

I have been a part of many of these discussions. I have seen what Diamondpilot has posted in the past. I usually am on the same side of the arguement with Diamondpilot (high five) but disagree with putting on a heavier hitch to avoid using a WD hitch for the reasons I have stated. In addidtion, who has tested the truck frame to be strong enough for these higher loads?

A WD hitch is going to put at least as much strain on the frame as a non-WD hitch. Think about the loading, instead of vertical downward loading in the back of the hitch, you now have upward loading on the back of the hitch and at least as much downward loading on the the front of the hitch. See below for an illustration

What WD gives you is less bending movement on the hitch which allows a lighter (and cheaper) crosstube.

I am fully aware of towing guidelines. I see that you are correctly posting many good things since this eye opening experience that I helped you with. I am just pointing out that the towing capacity of any rig is equal to the weakest link of the chain. If you have a F450 pulling a load with an 1 7/8" ball rated at 3500 lbs, the towing capacity of that setup is 3500 lbs even though every other limit is much higher in the equation.

Agree 100%.

Aaron Z

 

[joshuabardwell]

I really doubt this is the case. They are probably testing the hitches in a solid rig for failure rates. Are you saying it is safe to pull these large loads using a 3/4 ton pickup without a WD setup even after all the discussion of distributing some of the weight to the front tires of the tow vehicle?

I'm familiar with that effect of a WD system, and I really don't mean to be making any bold statements here about what is or isn't safe. The manufacturer of the hitch probably hasn't tested to see whether a given truck is safe to drive with a given tongue weight, no. But you asked specifically about damaging the frame. And I gotta say, if the manufacturer says I can put a certain hitch on my truck and have a certain tongue weight, I'd be shocked if they hadn't found out whether that was going to damage the frame or not--if not through rigorous testing, then through the number of warranty claims and lawsuits they would get if it did. If Jim-Bob is towing down the road with his front wheels in the air and he gets into an accident, it's obviously his own dang fault. But if he hitches up his trailer (under rated weight, of course) and his frame bends, he's going to go back to the manufacturer and point to the placard on the hitch and ask for compensation.

 

[slowzuki]

Not really since it is actually reversing the conventional torque load on the tube to the other direction to load the front tires. Can't really make it lighter.

What WD gives you is less bending movement on the hitch which allows a lighter (and cheaper) crosstube.

 

[slowzuki]

The truck manufacturers provide a maximum moment accessories can put on the truck frame broken out by which frame (different options get you different thickness and tensile strength). You may not realize but slight differences in trucks result is different wall thickness and tensile strength steel being used.

 

[wolfpack2]

To fully understand why there are two ratings for the hitch, you need to read and understand SAE J684. It defines the load and testing criteria for hitches. Because the ball is not in a straight line parallel to the ground, there will be a moment around the hitch that will be offset to some extent by the WD setup. This results in a higher overall trailer weight capacity for the WD vs. Weight Carrying condition. The V5 label on the hitch is required by federal regulations for all newer hitches and lists the hitch capacity. It will be used against you in court if you are overloaded and have an accident and get sued. When in doubt, stick the manufacturers published limits. They are there to protect us all.

 

[meburdick]

Every manufacturer advertises their vehicle's "max towing capacity" as what it is... the "max" capacity. That 2500 has a max towing capacity of 10,000 lbs. The "fine print" will tell you that you will need to achieve this limit by way of using a WDH, and if you do not, you will not be able to tow a trailer with a GTWR of over 5,000 lbs. That number is NOT the max towing capacity.

If the max tongue weight were 700 lbs, the max trailer weight without a WDH would be 7,000 lbs. It is EXACTLY a factor of 10 between the two because of the max tongue weight and the fact that it must represent no less than 10% of the GTWR.

I understand that a limit was exceeded, I understand that "weakest link in the chain" notion. I've said this before, and I will say it again... I'm not trying to tell anyone that the numbers advertised by the manufacturer are wrong... I am merely trying to help people understand WHY the numbers without a WDH come out as they do. I am in complete agreement with Wolfpack2 and the statement about adhering to guidelines.

The comment about a WDH being there to "change the center of gravity" isn't really correct. It's referred to as a "weight distributing" hitch for a reason... It's purpose is to distribute some of the tongue weight of the trailer to axles other than the rear axle of the tow vehicle. As a result, the center of gravity will change, but that isn't its sole purpose.

I can't speak for DiamondPilot, but I have a '11 Tundra with the integrated hitch. Maybe the comments you're thinking of are mine.

 

[jejeosborne]

I'm familiar with that effect of a WD system, and I really don't mean to be making any bold statements here about what is or isn't safe. The manufacturer of the hitch probably hasn't tested to see whether a given truck is safe to drive with a given tongue weight, no. But you asked specifically about damaging the frame. And I gotta say, if the manufacturer says I can put a certain hitch on my truck and have a certain tongue weight, I'd be shocked if they hadn't found out whether that was going to damage the frame or not--if not through rigorous testing, then through the number of warranty claims and lawsuits they would get if it did. If Jim-Bob is towing down the road with his front wheels in the air and he gets into an accident, it's obviously his own dang fault. But if he hitches up his trailer (under rated weight, of course) and his frame bends, he's going to go back to the manufacturer and point to the placard on the hitch and ask for compensation.

I have read some of the manuals that come with these aftermarket hitches and they all say that you should follow the vehicle manufactures recommended weights as published in the manual. That is an easy out for these hitch manufacturers. I agree that your dodge truck should be rated higher than the 350 lb tongue limit that is stated in your manual but to up it with an aftermarket hitch rated for 1500 lbs without a WD in play is flirting with disaster not just in the stress on the frame but the handling characteristics of that setup. Here is a good article on this subject. Don't be afraid to be bold if your think something is not safe. It might be an innocent life you are protecting. Not that I want to over dramatize the issue but I am seeing a lot of people towing dangerous setups and not even knowing it. If Jim-Bob kills a family member I will be even more active.

http://m.trucktrend.com/features/tech/163_0812_towing_liabulity_and_equippment_issues/viewall.html