$500 math question on extending ball mount shank

[path1]

For every inch I extend ball mount shank how much additional force (psi, torque, etc) will be generated on hitch receiver? Any rule of thumbs or formulas? Was hoping people would reply in percentages being our weights differ.

Reason for wanting a longer shank is for tighter turns, especially when backing.

Reason for $500 is because that is approx. what it will cost me if I need beefier hitch receiver.

Thanks

[path1]

blt2ski wrote:
If one of the reasons for extending the ball back some, is to Jack knife the trailer per say......the best way to fix this, is extend the tongue of the trailer, so you have at least 4',4.5' to the trailer body or part that will hit.
I've also found that the longer the trailer from ball to axles, is easier to control backing. As truck will usually out turn the trailer easier. I also prefer the pivot closer to the TV axle vs far behind for handling issues as mentioned by some too. Although, I have to admit, most of the.trailers I pull do not use WD systems.

My 02 on this.

Marty.

"the best way to fix this, is extend the tongue of the trailer"

I'm thinking "extend" as in splice in some metal or a new "A" frame to hitch ball coupler. Is that what your suggesting?

(Yes, I agree with sliding axle sucked all the way up, makes trailer respond quicker when backing trailer. I think it would NOT matter if WD system was installed or not. Shorter distance to pivoting points equals faster response.)

[blt2ski]

If one of the reasons for extending the ball back some, is to Jack knife the trailer per say......the best way to fix this, is extend the tongue of the trailer, so you have at least 4',4.5' to the trailer body or part that will hit.
I've also found that the longer the trailer from ball to axles, is easier to control backing. As truck will usually out turn the trailer easier. I also prefer the pivot closer to the TV axle vs far behind for handling issues as mentioned by some too. Although, I have to admit, most of the.trailers I pull do not use WD systems.

My 02 on this.

Marty.

[path1]

Op here...Yes, for WD hitch...going to study that thread and work some numbers.

Found the answer at least for me ...later in the orginal thread from 2010 Ron posted...

Ron Gratz wrote:

You probably can find a used Hensley Arrow for a lot less than $2500.

The added length of the HA would give you about a 12" extension.

Ron

Getting a Hensley or probably a pro pride would solve my problem. There we go, case solved..without using math:C

[Huntindog]

Is this for use with a WD hitch?

If so, then it won't make any difference.

We had a long thread on this a while back. A manufacturer (IIRCC, Torklift) and an engineer (Ron Gratz) were involved.
The result was that when using WD, the effect is nil. If not, then derating comes into play.
The hitch extension that was brought up earlier, is NOT for use with WD, so that would not apply.

Happy reading

[Slownsy]

The further back the ball is from rear axle the more weight removed from front, and the greater bending force applied to chassis, have seen plenty of pictures of bend chassis.
Frank.

[mkirsch]

Keep in mind that is not a manufacturer's website. If you go look those products up on the manufacturer website(s), I don't think you'll find any "50 percent" language. I sure haven't. The capacity of the extension is as marked on the extension, 350lbs tongue, 3500lbs trailer.

With that information in hand, my conclusion is this 50 percent rule is something etrailer.com made up for CYA purposes, and/or perhaps to reduce the number of questions on the product.

My guess here is that inches matter, but not nearly as much as etrailer.com makes it out to be. For sure you know the reduction is no more than 2.77 percent per inch, as that is what etrailer.com's claim on the 18" extension works out to be. As an engineer and only looking at it from a 500' view, I would be inclined to think that the reduction is closer to 2 percent per inch, if not less, but it also may not be linear.

[path1]

Op here....Good question, I haven't made it down to Torklift yet. And unsure when I'll be able to. But going to see if they have the math "long hand" to see exact numbers. Thanks for bringing that out. If inches matter...why doesn't math work by the inch on their extensions.

[mkirsch]

path1 wrote:
Op here, Thank you...So, every inch of extension I loose 4.17 percent.

I did read on-line (unknown if true or not) that hitch ratings are based upon... 10 inches back from hitch cross member at center mass. So the first 10 inches are free then after 10 inches subtract 4.17 percent for every inch.

Not so fast.

If you look at that hitch extension, it's actually only an 8" extension.

The 12" extension listed below it also has the same 50 percent reduction in capacity.

Scroll down a little farther, and the 18" extension has the same 50 percent reduction in capacity.

How can three vastly different length extensions have the same 50 percent reduction in capacity?

[atreis]

demiles wrote:
In the SAE j2807 standard they set the distance from the pin hole to the ball center to 15.88 inches for WD 12k or less and 11.88 inches for WD above 12k. The max trailer tow rating with 10% hitch weight is set using these distances so there is a “standard” or recommendation per say.

FWIW - 40 cm and 30 cm respectively. (These things would be so much easier if we would just switch ...)

[joshuajim]

ken56 wrote:
Length most certainly makes a difference. Look up aircraft weight and balance and turning moments (and it has nothing to do with turning). You certainly can overload your receiver by extending the shank.

OMG, the plane will crash if the pilot leans back 4". 🙂

[ken56]

Length most certainly makes a difference. Look up aircraft weight and balance and turning moments (and it has nothing to do with turning). You certainly can overload your receiver by extending the shank.

[joshuajim]

On my 10K equal-i-zer that would result in about a 15” shank. That’s considerably longer than most people use.

[demiles]

In the SAE j2807 standard they set the distance from the pin hole to the ball center to 15.88 inches for WD 12k or less and 11.88 inches for WD above 12k. The max trailer tow rating with 10% hitch weight is set using these distances so there is a “standard” or recommendation per say.

[joshuajim]

Receiver manufacturers DO NOT specify a shank length because 2 inches or 4 inches makes no difference. If you went to a slide in shank which was 24 inches long, then it makes a difference.

If a small change in shank made a difference, their lawyers would have 10 warning stickers on the receiver.

Relax.