16 in Shank on WDH

Long levers exert more force than short levers. Simple physics. Is it enough to cause problems. Likely not but it could. Lots of folks do it and get away with it. Lots of folks run old tires and get away with it. Lots of folks are overloaded. Lots of folks don't have brakes on their towed vehicle. People get away with many things that are wrong. In the words of Dirty Harry "Do you feel lucky today . . .?

coolbreeze01 wrote:
I like being able to drop mt tailgate while hooked up.

Me too. I thought that is what this thread was about but obviously I was wrong. Be nice to hear back from the OP.

I like being able to drop mt tailgate while hooked up.

SoCalDesertRider wrote:

...snip.....
Ron's a very smart man. When he figures something out, it's right.

I did not see where the OP was using a Weight Distributing hitch. Many don't with a 3/4 ton tow vehicle. I still prefer to have the ball as close to the rear axle as possible. Less chance of the "tail wagging the dog".

TomG2 wrote:
Quoting Ron: "The second year engineering student would conclude using the extension, with WD, results in less "stress on the hitch attachment points and truck frame"."

Therefore, we should all put a foot or two extension on our hitch bar to reduce the stress on the hitch and frame?

According to Ron's calculations, it can help, rather than hurt, the tongue weight capacity of the hitch, depending on the right combination of weights and lengths, IF YOU ARE USING WEIGHT DISTRIBUTION. If not, then it is the opposite, stress is increased when weight carrying with an extension shank.

Ron's a very smart man. When he figures something out, it's right.

Quoting Ron: "The second year engineering student would conclude using the extension, with WD, results in less "stress on the hitch attachment points and truck frame"."

Therefore, we should all put a foot or two extension on our hitch bar to reduce the stress on the hitch and frame?

Here is what our resident engineer, Ron Gratz had to say on this back in 2010:


Quote:

---A first year engineering student can figure this one out. The longer draw bar and the farther back you get from the tow vehicle, the more stress you put on the hitch attachyment points and truck frame.

But, a second year engineering student probably would be aware that the OP is using a weight distribution hitch.

So, let's assume the tongue weight is 1000# and the WD bars are loaded so they exert a pitch-axis moment of about 2000# x 30" = 60,000 lb-in on the hitch head. This moment, when viewed from the driver's side, acts in a CCW direction.

Now, assume the WD system reduces the vertical load on the hitch head to 800# and let's assume this force, on the non-extended setup, acts at 10" from the receiver crosstube. This generates a CW moment of 8,000 lb-in. Combining the two moments gives 60,000 CCW plus 8,000 CW = 52,000 lb-in CCW.

Then, let's extend the tow tube so the vertical load acts at a distance of 20" from the crosstube. The vertical load now generates a CW moment of 16,000 lb-in, and combining the moments gives a CCW moment of 44,000 lb-in. The second year engineering student would conclude using the extension, with WD, results in less "stress on the hitch attachyment points and truck frame".

I don't think any one of us really knows why the use of a specific extension does or does not result in a reduced rating.

There are many examples of the "internet myths" mentioned by Larry. Gander Mountain sells an 18" extension and says, "Reduces hitch capacity by one third."

Trailerhitches.com says, "Extenders come in several different lengths from 6" to 48"." And then they state unequivocally, "Hitch extensions are mandatory for some types of towing, but they do have one large disadvantage, they towing capacity is reduced by 50 percent." Are we to assume the 50% applies to everything from 7" to 48"?

Cabela's sells 7", 12", and 18" extensions and state (regardless of length), "Use of this extender will reduce the vehicle hitch's overall tongue weight capacity to 1/3 of original capacity. Example: 900 pound tongue capacity would be reduced to 300 pounds."

So, depending on the source, the alleged capacity reduction when using probably the same hardware, might be 33% or 50% or 67%. Reese, OTOH, justs lists a capacity for the extension and doesn't say anything about reducing the capacity of the receiver.

If you're going to use an extension, there's probably not much point in speculating why there is or is not a recommended rating reduction. And, if the seller says the extension reduces the allowable tongue weight or towing capacity by 1/3 or 1/2 or 2/3, you might want to ask why.

Ron


This particular thread had a lot of discussion about generic hitch extensions, which are a totally different animal that a longer drawbar, in that WD cannot be used with them... But the math for the WD differences is enlightening

Link:WD and longer drawbars explained

Most things have a safety factor and it is not surprising to get by with something for 6, 8, or 10 years. That does not change the engineering involved. What kind of WD hitch was the OP using?

TomG2 wrote:
It may be WAGGING, and I will not go through the physics involved, but it makes a sizeable difference in the forces involved in the receiver hitch whether the lever arm is 10 inches or 16.

The real problem is YOU CAN'T go thru ANY PHYSICS that are based on real facts concerning what if any these additional lengths really effect the wt. ratings for that receiver. The wt. ratings for the receiver could be based on a 24" lever and in that case any drawbar length will have NO EFFECT on the receiver's capacity. No where are there any FACTS on exactly how a receiver's wt. rating is determined and my contention is that they are most likely designed to be used with any normally available drawbar available and that is why no receiver has any wt. rating adjustments for drawbar length.

SO YES KEEP ON WAGGING cause that's all you're doing IMO.

Larry