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Old 12-15-2018, 09:49 AM   #1
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Keyboard engineers opine?

I have a new shank that's 3" longer than my current shank on the Equalizer hitch.
Before I try it I was wondering how it might effect my WD.
Being longer, I assume it will create a longer lever arm for a given tongue weight. Thinking the fulcrum is the front axle.
However, doesn't that also mean the WD bars will have a greater effect and the net result be the same?
I currently have 5 washers and a bit of sag. I'm thinking while I have it apart I'll add another washer.
Currently, it tows perfectly. Not being to open the tailgate while hooked up is a pain.
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Old 12-15-2018, 09:56 AM   #2
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"A bit of a sag". How much is a "bit"? If you are comfortable with it as is, I wouldn't add a washer unless your theory mentioned above proved to be true.



I think weighing your set up before and then after would tell you a lot.
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Old 12-15-2018, 10:09 AM   #3
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I had a shop drill a second pin hole in the my Equalizer shank for the express purpose of keeping its extension as short as possible. This was on the advice of CaAm Andy. Having the ball as close to the rear axle as possible keeps the weight and sway leverage to it's minimum.

I also spoke to Equalizer, they said they drill the pin hole on the shank the way they do for people that want to attach those slide on mud and rock guards. They had no issue with me drilling a second hole making the effective shank extension about 3" shorter.

I have about 25,000 miles now on my hitch. I've found it necessary to add a washer of two over time to compensate for wear in.
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Old 12-15-2018, 10:46 AM   #4
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I believe I was summoned?!

For this situation in restoring front axle FALR, the fulcrum should be modeled at the hitch ball. So the WD bars lever arm didn't change in length at all. But the lever arm to restore FALR just got 3" longer. Reducing WD bar leverage.

Yes, you'll want to increase WD tension to get back to what you were at. An added washer should do it.
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Old 12-15-2018, 11:19 AM   #5
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you need to keep the ball as close to the female end of the TV shank as possible.

The longer it is, the higher the pivot point away from your vehicle and less stable is the WD/Anti sway.

go to the the CAN-Am RV video page and they will show you why

There are also many threes on this forum with the same Q&A.

search for more details

cheers
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Old 12-15-2018, 11:45 AM   #6
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Quote:
Originally Posted by Mollysdad View Post
I have a new shank that's 3" longer than my current shank on the Equalizer hitch.
Before I try it I was wondering how it might effect my WD.
Being longer, I assume it will create a longer lever arm for a given tongue weight. Thinking the fulcrum is the front axle.
However, doesn't that also mean the WD bars will have a greater effect and the net result be the same?
I currently have 5 washers and a bit of sag. I'm thinking while I have it apart I'll add another washer.
Currently, it tows perfectly. Not being to open the tailgate while hooked up is a pain.
I would consider the fulcrum to be the rear axle, so for the front axle load restoration you would just need some additional leverage from the WD bars with the additional rear offset caused by the longer shank.

The bigger issue, in my mind, isn't one of consideration of the vertical plane and the load restoration, since that can be accommodated with WD settings. I would think more about the horizontal plane. Any lateral forces act on the hitch ball and can cause sway because they are offset from the rear axle, which is where those lateral forces are resisted. You can't change settings to accommodate this longer lever arm you are setting up, there is simply more leverage side to side (unless you are using a 3P hitch design).
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Old 12-15-2018, 12:02 PM   #7
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Hi

The relevant measure is from the hitch ball to the center of the rear axle. You are moving things three inches out of a couple feet. Getting more exact than that would require a bit of data about your exact truck and the rest of the hitch setup.

Bob
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Old 12-15-2018, 01:18 PM   #8
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I believe closer to the TV axle is to help mitigate sway, 3" won't +/- WD much at all.😉

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Old 12-15-2018, 01:50 PM   #9
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Make it short. You can make it long? Folks do it. They also raise the coach, raise the TV, run without using the trailer brakes on down hill grades and other stuff too. They do what they want to do. So, if you do, do it, slow down at least a tad. Don't pass so much, follow a bit further back and get extra rest each day. Compensate for your shift to less than optimum engineering spec by adjusting the usage profile.

And note that a keyboard engineer can not help you. They are much too far from the wheel, the brake, the mirrors and the turn signal.

Travel safe. Pat
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Old 12-15-2018, 02:05 PM   #10
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Quote:
Originally Posted by jcl View Post
I would consider the fulcrum to be the rear axle,
Here's why I said the front axle.
By adding more tension to the WD bars the effect is a lifting of weight off the rear axle and moving it to the pivot point on the front axle. If the rear axle is the fulcrum, the rear end of the truck would not move as weight is transferred.

Quote:
Originally Posted by waninae39 View Post
you need to keep the ball as close to the female end of the TV shank as possible.
Of course, but it doesn't help me open the tailgate. It's all compromise.

Quote:
Originally Posted by ROBERT CROSS View Post
I believe closer to the TV axle is to help mitigate sway, 3" won't +/- WD much at all.��
That's what I think too. Making the lever arm longer is offset by making the WD effect greater.
Sway? I have never had a hint of sway, so 3" will suddenly cause a rollover? I don't think so.
BTW, since driving with the trailer, I make a habit of looking at other trailers I see on the highway. Horse trailers, boat trailers, car trailers, motorcycle trailers, utility trailers, and you know what I don't see? A WD hitch on any of them. The WD hitch seems to be unique to travel trailers.
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Old 12-15-2018, 02:43 PM   #11
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Quote:
Originally Posted by Mollysdad View Post
Here's why I said the front axle.
By adding more tension to the WD bars the effect is a lifting of weight off the rear axle and moving it to the pivot point on the front axle. If the rear axle is the fulcrum, the rear end of the truck would not move as weight is transferred.
You can use either as a fulcrum, depending on what you want to calculate. Enter your figures in the calculation here:

https://www.rv.net/forum/index.cfm/f...d/14265335.cfm
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Old 12-15-2018, 04:34 PM   #12
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You can use either as a fulcrum, depending on what you want to calculate. Enter your figures in the calculation here:

https://www.rv.net/forum/index.cfm/f...d/14265335.cfm
Yes, it's a complex system and depending on what one wants to model, would use a different fulcrum.

Consider this particular case where we're talking about adding 3" to the shank, and whether we need to increase WD tension.

If you modeled the fulcrum at the rear axle, increasing shank length should give the WD more leverage. Increasing front axle weight restoration.

That is not the case here. Which would indicate the rear axle is not the fulcrum.

The ball is where the effective fulcrum is for the WD bars. He will need to add more WD tension.
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Old 12-15-2018, 05:17 PM   #13
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Originally Posted by pteck View Post
Yes, it's a complex system and depending on what one wants to model, would use a different fulcrum.

Consider this particular case where we're talking about adding 3" to the shank, and whether we need to increase WD tension.

If you modeled the fulcrum at the rear axle, increasing shank length should give the WD more leverage. Increasing front axle weight restoration.

That is not the case here. Which would indicate the rear axle is not the fulcrum.

The ball is where the effective fulcrum is for the WD bars. He will need to add more WD tension.

Take a look at the link and the formulae there.

The trailer side doesn't change with the lengthened shank, so there is still the same increased load on the trailer axles, using the ball is the fulcrum for the WD bars, as you said.

Now use the rear axle as a fulcrum to calculate changes on the front axle from the increased shank length.

Use the front axle as a fulcrum to calculate changes on the rear axle from the increased shank length.

Agree he needs more WD tension to get the same effective change to the TV axle loadings.


T
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Old 12-15-2018, 05:47 PM   #14
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Agree he needs more WD tension to get the same effective change to the TV axle loadings.
That's the question.
However, I must disagree.
How can one say the longer shank makes for more leverage on the rear of the TV(agree), but not consider that the sway bars also provide additional lift to the chassis? (having a longer lever arm)
I contend it's a zero sum game.
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