Shank length on draw bar --longer or shorter? - Page 2 - Fiberglass RV


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Old 08-29-2015, 12:07 PM   #15
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Originally Posted by Ellpea in CA View Post
I need to get a draw bar to connect Volvo to Lil'Bigfoot.

These apparently have a choice of shank *lengths.*

DH is on top of the height we need from ground to top of ball, but we haven't discussed the shank.

Is there an ideal shank length (to allow adequate turning clearance from bumper to trailer)?

If it helps, the V70 is more rounded on the corners than the previous, more boxy models.
Floyd said it best. Keep the ball as close as you can to your rear bumper.
This has two advantages: It reduces the leverage the trailer hitch weight has to cause your car to sag on its springs; and it reduces the tendency for trailer sway. Also, pay attention as to how snug the stinger is in the receiver. If loose, it will aggravate the tendency for trailer sway.
To get the ball in close, I had to drill another hole in the shank. To take out the play (looseness) I added shims at the side and bottom, and drilled and tapped a hole in the bottom of the receiver, forward, for a 3/8 fine thread set screw .... which must be loosened to get the stinger out, and tightened after you put it in.
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Old 08-29-2015, 12:20 PM   #16
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I think what we sound up with will do nicely. DH was pretty careful (with his height measurements and all), just to make sure we were in the ballpark. He got the receiver that put us closest, but we will have to move it out and hitch up to make sure we're level.

Carol, that's good to know about the wind and the slight dip in front, how the behavior of the trailer changes with different TV's, and also about the reversal of the draw bar. I guess there could be controversy about that as well as everything else. Due to the angle of the weld, it does look stronger in one direction than the other, but I do believe it's safe either way (especially since we wound up with such a honking big draw bar rated for much more than 3500 lbs, and our trailer weighs less than 2000)!

LOL, DH just came in and said the nose down concept is like the "Nascar Rake." I guess he would know. He also says that the rounded trailer is less affected by the "rake" than is a square trailer (and wind, of course). In other words, he very much likes the concept of the shape of our eggs, and is getting more enchanted every day (I can tell)!
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Old 08-29-2015, 12:56 PM   #17
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Originally Posted by Ellpea in CA View Post
In other words, he very much likes the concept of the shape of our eggs, and is getting more enchanted every day (I can tell)!
Aerodynamics and towing........... perfecto!.
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Old 08-29-2015, 01:16 PM   #18
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If you check the unloaded height of the rear and compare to the laden height this will usually cause the camber to increase and perhaps the toe out as well.
This is not an issue with a solid rear axle, but with the IRS it could be.
The suspension is designed to work within a range of ride height and if it is lower tire wear could be accelerated and also not handle as well.
The Airbags simply put the suspension in the proper area.
Again research indicates that the use of airbags to level the TV provides 1/2 of the benefit of having a weight distribution hitch. Mostly by putting the rear end at the proper level. This provides more advantageous roll coupling front and rear and with the trailer. The leveling of the TV with the WD is a large part of the reason for it's use.
The other is the transfer of weight off the rear to the front wheels and the trailer wheels. A lot of stress accompanies this weight shift as well. This is of course why many manufacturers discourage the use of WD hitches.
If you want 1/2 of the benefit of the WD hitch, and a level car so that the headlights are the same towing or not, keep the rear tires from wearing, and improve the handling for about $100.00 then try it.
If it doesn't match your idea of the proper universe then (of course) don't add them. They do not add load capacity to the car, just add enough spring rate to bring the car back to level with the additional load.
The reason I brought it up is if you measure the ball height of the trailer hitch and set the ball on the car at that level then you merely add air to keep it there when loaded.
Lots of benefit and little cost.
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Old 08-29-2015, 01:32 PM   #19
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Quote:
Originally Posted by Ellpea in CA View Post
I think what we sound up with will do nicely. DH was pretty careful (with his height measurements and all), just to make sure we were in the ballpark. He got the receiver that put us closest, but we will have to move it out and hitch up to make sure we're level.


LOL, DH just came in and said the nose down concept is like the "Nascar Rake." I guess he would know. He also says that the rounded trailer is less affected by the "rake" than is a square trailer (and wind, of course). In other words, he very much likes the concept of the shape of our eggs, and is getting more enchanted every day (I can tell)!
LOL well you can tell the DH that the trailer pulled by both vehicles was a round Scamp. BTW putting the tongue to far down can also result in undesirable consequences.

The bottom line is there is a number of things that impact how stable a tow is behind any particular vehicle - as some have suggested the distance between the hitch and the axle is one of them, another is the actual center of gravity of the trailer itself - that will be different with each trailer depending on its layout and placement of water tanks etc. and how one loads it up. The trailers tongue weight - due to interior design and storage space locations will always be lighter on some trailers when fully loaded than another may be & little can be done in regards to how it is loaded to change that.

I was able to achieve a very solid tow with a level trailer when towing with a vehicle that the axle was closer to the hitch and the vehicle itself was a bit heavier on the back end vs pulling the same trailer with a vehicle that has a greater distance between the axle & the hitch and the vehicle itself is a bit lighter in the back end. The later vehicle needs a bit more weight on the tongue of the trailer for a solid tow in windy conditions & traveling at highway speeds and the only way to achieve that due to the lack of storage areas ahead of the axle in the trailer is to put the tongue down slightly that is hardly noticeable to the eye when hooked up.
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Old 08-29-2015, 06:31 PM   #20
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...
As far as getting the right height goes the only sure way of doing that is to again load up the trailer and attach it to the car. Once you have towed it you may need to fine tune it and find yourself the proud owner of more than one draw bar. ;-) ....
How true.. I have three draw bars. If I had it to do over again, I would buy one adjustable. But now I might need sway control, so I might be buying more stuff anyway. Such is the life of a trailer owner.
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Old 08-29-2015, 06:46 PM   #21
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Originally Posted by Carol H View Post
...
As far as getting the right height goes the only sure way of doing that is to again load up the trailer and attach it to the car. Once you have towed it you may need to fine tune it and find yourself the proud owner of more than one draw bar. ;-) ....
Quote:
Originally Posted by gordon2 View Post
How true.. I have three draw bars. If I had it to do over again, I would buy one adjustable. But now I might need sway control, so I might be buying more stuff anyway. Such is the life of a trailer owner.
Perhaps you need a set of air shocks or bags?
Do you readjust your headlights each time you have a different loading or don't drive at night?
If a car is equipped with HID lights for example and it is from the factory it must have either self levelers or shutters or automatic headlight correcting systems.
A little more weight on the rear springs really calls for a little higher spring rate to keep the resonant frequency of the system higher and keep it further from the danger zone.
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Old 08-29-2015, 06:55 PM   #22
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Smile Suspension work

Changing the factory suspension may void your vehicle's warranty. Contact your dealership or the manufacturer before making any modification to your vehicle.

Lowering the suspension should be done with a sway bar replacement to prevent body stress, which can ultimately damage your vehicle.

Read more : http://www.ehow.com/how_6027255_choose-right-suspension-car.html

Our owner's manual says not to use weight distribution systems.
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Old 08-29-2015, 08:54 PM   #23
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Originally Posted by redbarron55 View Post
Quote:
Originally Posted by Carol H View Post
...
As far as getting the right height goes the only sure way of doing that is to again load up the trailer and attach it to the car. Once you have towed it you may need to fine tune it and find yourself the proud owner of more than one draw bar. ;-) ....

Perhaps you need a set of air shocks or bags?
Do you readjust your headlights each time you have a different loading or don't drive at night?
If a car is equipped with HID lights for example and it is from the factory it must have either self levelers or shutters or automatic headlight correcting systems.
A little more weight on the rear springs really calls for a little higher spring rate to keep the resonant frequency of the system higher and keep it further from the danger zone.
Nope there is nothing for airbags to fix. The vehicle is not dropping in the rear with headlights point to the sky as it has beefed up shocks & I am pulling a trailer well under half its towing spec. As I said every vehicle is different and some vehicles just like more weight on the tongue than another might in order to achieve a solid tow

There is an easy fix to the problem of using sway control on multiple receivers - Reese Sway Control Bracket for 3" Ball Mounts - Class III & IV.

You can use it & move it easily to any receiver/ball mount that you already own. No need to have a plate and ball welded to each one for the sway control.
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Old 08-30-2015, 12:41 AM   #24
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Originally Posted by redbarron55 View Post
If you check the unloaded height of the rear and compare to the laden height this will usually cause the camber to increase and perhaps the toe out as well.
This is not an issue with a solid rear axle, but with the IRS it could be.
The suspension is designed to work within a range of ride height and if it is lower tire wear could be accelerated and also not handle as well.
The Airbags simply put the suspension in the proper area.
Again research indicates that the use of airbags to level the TV provides 1/2 of the benefit of having a weight distribution hitch. Mostly by putting the rear end at the proper level. This provides more advantageous roll coupling front and rear and with the trailer. The leveling of the TV with the WD is a large part of the reason for it's use.
The other is the transfer of weight off the rear to the front wheels and the trailer wheels. A lot of stress accompanies this weight shift as well. This is of course why many manufacturers discourage the use of WD hitches.
If you want 1/2 of the benefit of the WD hitch, and a level car so that the headlights are the same towing or not, keep the rear tires from wearing, and improve the handling for about $100.00 then try it.
If it doesn't match your idea of the proper universe then (of course) don't add them. They do not add load capacity to the car, just add enough spring rate to bring the car back to level with the additional load.
The reason I brought it up is if you measure the ball height of the trailer hitch and set the ball on the car at that level then you merely add air to keep it there when loaded.
Lots of benefit and little cost.
Thanks JD, I'll have the hubby read this post.
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Old 08-31-2015, 06:29 AM   #25
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Again research indicates that the use of airbags to level the TV provides 1/2 of the benefit of having a weight distribution hitch. Mostly by putting the rear end at the proper level.
If air bags provide only 1/2 the benefit of a WDH why would a person choose air bags over a WDH?
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Old 08-31-2015, 06:42 AM   #26
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If air bags provide only 1/2 the benefit of a WDH why would a person choose air bags over a WDH?
That is a good question.

My thoughts....

The bags are cheaper and once installed you are done, unless you need to add or decrease air pressure. By comparison the bags tend to make for a rougher ride.

With a WDH more work and effort is required to install every time one hooks up or unhooks.

I agree, generally speaking the WDH is the way to go. Added stability and safety.
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Old 08-31-2015, 07:00 AM   #27
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The above and also they help with other loading issues as well.
The suggestion from the studies in the '70's is to use the two in combination.
The air bags took up all that they could and the hitch did the rest.
Part of the equation has to do with the spring rate of the rear eand suspension and the applied weight. When you add weight you lower the resonant frequency of the system. If the period of any oscillation (from incipient sway for example) is the same as the period of the spring system then the system will be unstable.

As an aside to Ellpea - Volvo has the shock in the middle of the springs and air bags will not fit. There are no air shocks to fit that I can find, but Volvo has some Hydraulic self levelers (very expensive) that may work. here is a picture of one:



It would seem that the only acceptable solution for many is a nice truck with a weight distributing hitch and all that entails.

Ride height is important and spring rate as well. The Volvo seems to have a pretty beefy rear suspension and I wouldn't worry about it. If you have many miles on the car you might consider freshening up the suspension. If the shocks would fit from other models then these migh be an option. There are cheaper places to buy the springs and shocks together. here is a video:


Monroe Nivomat - Shockwarehouse.com

What are Nivomat shocks and does my Volvo have them?
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Old 08-31-2015, 07:03 AM   #28
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If air bags provide only 1/2 the benefit of a WDH why would a person choose air bags over a WDH?
If that is all the weight transfer needed, that's why. It is a cheaper, simpler, lighter solution. You don't always need the biggest hammer...

Neither solution is inherently bad.
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