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Old 03-12-2012, 08:53 AM   #1
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Apparent Hitch height disparity ???

When checking the forums for recommendations as well as my owner manual, I come up with a hitch height of 17.75" (+.5-1.0) for ground to top of ball. However, when I set it up that way, I have a ground to lower main frame distance of 15.5" in the front and 17" in the rear on our FC20. If I "equalize" those ground to frame distances (at 16 5/16 for both front and rear of trailer frame) so that the frame and trailer are indeed level, it brings the ground to inside of coupler distance up to 20.5-20.75".

Should I be concerned about that 3" disparity? The factory spec puts me so low that the flip automatic jack foot often lacks the clearance to swing into either position. And you folks were right ... the dealer didn't set up the bars correctly either.
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Old 03-12-2012, 09:37 AM   #2
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this will be interesting to watch. I just got a new truck and had to put my hitch height up a little to make sure i was level. Hope to hear more about this. I feel that the 17.75 is a starting point. but I may be wrong. Lets here from all the experts.
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Old 03-12-2012, 11:26 AM   #3
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this will be interesting to watch. I just got a new truck and had to put my hitch height up a little to make sure i was level. Hope to hear more about this. I feel that the 17.75 is a starting point. but I may be wrong. Lets here from all the experts.
Your Airstream has torsion axles.

They are weight sensitive.

Any and all "tongue height" charts are sort of useless, other than as a starting point.

The ONLY true answer to that question, "is to mesure your coach, before hookup, but ready for a trip".

Then and only then, will you have the correct answer.

And yes, the same applies for a brand new trailer as well.

Andy
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Old 03-12-2012, 11:43 AM   #4
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Hitching up with an equalizer hitch and spring bars seems to be a thing that generates lots of opinions as to what is the "correct way". Here is what I have always done for the past 33 years. Up to my current TV, it has always worked very well.

1. Put the trailer on a dead level concrete pad, measure the frame bottom height front and rear, make them equal.
2. Measure the height of the coupler from inside to the concrete. That is your true hitch ball height to work with for your rig as you tow.
3. Use that dimension to set the hitch ball top height on your TV, as loaded the way you normally travel. I like to stay within a half inch + or -. This is parked, not hitched up.
4. With spring bars which are right for your hitch load (not too high a capacity) then hook up and use the spring bars to re set the new level on the front and back of the trailer to the same dimensions (that is level again).
5. Tow, see how it feels, make minor adjustments in spring bar tension (+ or - one link) to vary things.

If your TV is a stout truck, you may not have much drop when connected. I am not really sure how that comes into the picture, I have never had such a rig.

My current struggles are with a 2012 Jeep Grand Cherokee with automatic air springs and ride height adjustment which cannot be shut off. The above does not seem to work with it...but someone will know and explain that one of these days.

BTW, I am in Missoula often for shopping (once home from AZ, in about 3 weeks) and would be glad to stop in and work with you on it all. PM me if you would like.
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Old 03-12-2012, 11:54 AM   #5
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Hitching up with an equalizer hitch and spring bars seems to be a thing that generates lots of opinions as to what is the "correct way". Here is what I have always done for the past 33 years. Up to my current TV, it has always worked very well.

1. Put the trailer on a dead level concrete pad, measure the frame bottom height front and rear, make them equal.
2. Measure the height of the coupler from inside to the concrete. That is your true hitch ball height to work with for your rig as you tow.
3. Use that dimension to set the hitch ball top height on your TV, as loaded the way you normally travel. I like to stay within a half inch + or -. This is parked, not hitched up.
4. With spring bars which are right for your hitch load (not too high a capacity) then hook up and use the spring bars to re set the new level on the front and back of the trailer to the same dimensions (that is level again).
5. Tow, see how it feels, make minor adjustments in spring bar tension (+ or - one link) to vary things.

If your TV is a stout truck, you may not have much drop when connected. I am not really sure how that comes into the picture, I have never had such a rig.

My current struggles are with a 2012 Jeep Grand Cherokee with automatic air springs and ride height adjustment which cannot be shut off. The above does not seem to work with it...but someone will know and explain that one of these days.

BTW, I am in Missoula often for shopping (once home from AZ, in about 3 weeks) and would be glad to stop in and work with you on it all. PM me if you would like.
Unfortunately, as good as the "automatic leveling systems" seem to be, they are a definate safety hazard when used with a load equalizing hitch.

The auto system struggles to defeat every advantage the the load equalizing hitch offers.

As the hitch starts working, so does the auto system, which lifts the weight imposed on the rear end, therefore making the hitch almost totally useless.

The only "for sure and positive way" to use a self leveling system, with a load equalizing hitch, is to shut the leveling system OFF, when towing the trailer.

In that way, the hitch will perform it's intended duty, without any influence from a auto leveling system.

A scale, carefully used, will bear out that issue.

Andy
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Old 03-12-2012, 02:14 PM   #6
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I think this issue has become way to complicated.
Just hook the trailer to the TV on a pretty close to level flat surface.
Put a level on the floor of the trailer running fore and aft. This would be a good time to check the built in levels on the trailer. If they read what the level on the floor reads then you don't need the floor level.
If the level on the trailer indicates it is out of level from front to back simply make adjustments accordingly.
If the front of the trailer sets too high, lower the level of the hitch on the TV accordingly.
If the rear of the trailer sets to high, raise the level of the hitch on the TV accordingly.
There may be a need to change the setup based on whether the trailer is fully loaded and ready for travel as compared to being dry and without provisions.
In my case the dry tongue weight of my trailer is about 500#. When the fresh water tank and propane tanks are full the tongue weight is 860#. Mainly because the fresh water tank (30 gal) is across the front of the trailer. With the 360# difference I really don't see the need for any hitch adjustment.
The ball height specified is just a place to get started. The most important thing is that both the trailer and TV are as close to level as possible once you are hitched.
If your TV is lower in the rear than in the front and the trailer is lower in the front and you use a WD system, to make the adjustment just raise the hitched assembly until it is level (jack it up) then connect the stabilizer bars and lock them in. Remove the jack you used to raise the hitch and see if the rig sets level. If not, make another adjustment.
Once this setup is a established for your rig, unless there is a dramatic change in the load you are carrying or the TV you are using, it should remain unchanged.
I have read in a number of places that there are some auto leveling devices that can not be disabled because they are part of the overall stability control of the vehicle. I have also read that when you have and auto leveling system, some manufactures do not recommend the use of WD systems because of potential damage to the auto leveling system. Don't know how factual this is.
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Old 03-12-2012, 02:40 PM   #7
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When checking the forums for recommendations as well as my owner manual, I come up with a hitch height of 17.75" (+.5-1.0) for ground to top of ball. However, when I set it up that way, I have a ground to lower main frame distance of 15.5" in the front and 17" in the rear on our FC20. If I "equalize" those ground to frame distances (at 16 5/16 for both front and rear of trailer frame) so that the frame and trailer are indeed level, it brings the ground to inside of coupler distance up to 20.5-20.75".

Should I be concerned about that 3" disparity? The factory spec puts me so low that the flip automatic jack foot often lacks the clearance to swing into either position. And you folks were right ... the dealer didn't set up the bars correctly either.
Not sure how you came up with 17.75" or whether your current setup is right. The rear springs of the tow vehicle will compress somewhat when hitched. Perhaps your original figure didn't account for that.

Regardless of what process you use to arrive at hitch heights and WD bar settings, the end result should be that the trailer is level and there is no less weight on the front axle of the tow vehicle than there is without the trailer hitched up.
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Old 03-12-2012, 05:59 PM   #8
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Many thanks for all of the comments. I was just a bit unsure of myself with the ~3" disparity between what the AS factory (and owner manual) says the hitch ball height should be (17.75") and what I actually need by leveling the trailer fore and aft and then measuring the distance from the cement ground to the inside of the coupler (20.5-.75").
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Old 03-12-2012, 07:30 PM   #9
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Unfortunately, as good as the "automatic leveling systems" seem to be, they are a definate safety hazard when used with a load equalizing hitch.

The auto system struggles to defeat every advantage the the load equalizing hitch offers.

As the hitch starts working, so does the auto system, which lifts the weight imposed on the rear end, therefore making the hitch almost totally useless.

The only "for sure and positive way" to use a self leveling system, with a load equalizing hitch, is to shut the leveling system OFF, when towing the trailer.

In that way, the hitch will perform it's intended duty, without any influence from a auto leveling system.

A scale, carefully used, will bear out that issue.

Andy
And:

I have read in a number of places that there are some auto leveling devices that can not be disabled because they are part of the overall stability control of the vehicle. I have also read that when you have and auto leveling system, some manufactures do not recommend the use of WD systems because of potential damage to the auto leveling system. Don't know how factual this is.


I did not mean to hijack this thread, my apologies to the original poster.

Andy: I don't disagree with you at all, the unfortunate thing is on the Air Suspension Jeep Grand Cherokee I have (2012 Overland) there is no way to turn the self leveling off once the vehicle is in motion. You can lower it under 15 mph but once you get above that speed, it is always in operation. It has no conventional springs, the self leveling and spring function are all part of one package. The rig is sold with a 7400# tow rating listed in the literature.

In addition, the Jeep manual says that for hitch weights above 500# a weight distributing hitch is "required" and yet there is no instructions as to how to set it up.

So, here I am with a requirement for the WD hitch, and I agree with that having 33 years of experience with them. Yet, when I try to adjust it the way I always have, the automatic load leveling which cannot be disabled, causes the spring bars to hang essentially loose. I only have 1000 towing miles on the rig and it has been rock stable, but the WD hitch is not doing anything, which concerns me.

I am hoping that someone at Jeep is listening to owners of 2011 and 2012 Grand Cherokee's and has come up with a solution. I will be checking back with my dealer as soon as I return north and am into another towing season.

Anyone with a solution to this or any posts from other forums would sure be appreciated.
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Old 03-13-2012, 01:42 AM   #10
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And:

I have read in a number of places that there are some auto leveling devices that can not be disabled because they are part of the overall stability control of the vehicle. I have also read that when you have and auto leveling system, some manufactures do not recommend the use of WD systems because of potential damage to the auto leveling system. Don't know how factual this is.


I did not mean to hijack this thread, my apologies to the original poster.

Andy: I don't disagree with you at all, the unfortunate thing is on the Air Suspension Jeep Grand Cherokee I have (2012 Overland) there is no way to turn the self leveling off once the vehicle is in motion. You can lower it under 15 mph but once you get above that speed, it is always in operation. It has no conventional springs, the self leveling and spring function are all part of one package. The rig is sold with a 7400# tow rating listed in the literature.

In addition, the Jeep manual says that for hitch weights above 500# a weight distributing hitch is "required" and yet there is no instructions as to how to set it up.

So, here I am with a requirement for the WD hitch, and I agree with that having 33 years of experience with them. Yet, when I try to adjust it the way I always have, the automatic load leveling which cannot be disabled, causes the spring bars to hang essentially loose. I only have 1000 towing miles on the rig and it has been rock stable, but the WD hitch is not doing anything, which concerns me.

I am hoping that someone at Jeep is listening to owners of 2011 and 2012 Grand Cherokee's and has come up with a solution. I will be checking back with my dealer as soon as I return north and am into another towing season.

Anyone with a solution to this or any posts from other forums would sure be appreciated.
Here is something that you can try.

Install a air pressure gauge into the line that goes to the air bags or air shocks, as the case may be.

Then install a switch into the wire that feeds the air compressor, so that when your going to hook up the hitch, you can shut the system off, before you attach anything to the Jeep.

Then, with the air guage, you can monitor the air pressure to make sure of what pressure you started with and to make sure it stays at that same pressure. If it should drop, then you could turn the compressor back on, but just long enough to replace the lost pressure, if any.

Andy 12900
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Old 03-13-2012, 08:49 AM   #11
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I would bet that modifying the system on your 2012 Jeep would void the warrantee.
If the auto leveling system is taking the tension off of the bars on the WD system. Isn't it accomplishing the ultimate goal? In that it (the auto leveling) is keeping the rig level. If the rig tries to bend I would think the bars would prevent it.
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Old 03-13-2012, 09:02 AM   #12
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I would bet that modifying the system on your 2012 Jeep would void the warrantee.
If the auto leveling system is taking the tension off of the bars on the WD system. Isn't it accomplishing the ultimate goal? In that it (the auto leveling) is keeping the rig level. If the rig tries to bend I would think the bars would prevent it.
I think the point is, if you have proper WD and the whole TV now rides 3/4" lower due to WD (key off and air system is not functioning), when the air pump raises the TV, it unloads the WD and thus you may be back to an overloaded rear axle (in some cases) and an unbalanced rig (in some cases).

Looking level and balanced is never accurate......and when you apply an air leveling system, it further masks improper load and balance.

Each brand and air leveling system design is going to be different in its behavior and it is really necessary to understand and compensate your individual system and setup.
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Old 03-13-2012, 10:04 AM   #13
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If the auto leveling system raises the tongue height to where the weight is shifted to the rear axle of the trailer. Then you need to adjust the height of the ball to get the trailer back to level.
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Old 03-13-2012, 10:29 AM   #14
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If the auto leveling system raises the tongue height to where the weight is shifted to the rear axle of the trailer. Then you need to adjust the height of the ball to get the trailer back to level.
That's true and that's where knowing you particular system and dialing in the setup is essential.
Here's what I do with the GM system.
1)Pull the fuse for auto level control
2)load truck and trailer as ready to go
3)dial in the WD for proper WD and level of vehicle and AS, per weights and measures.

If this is done properly, the rear of the TV is usually about 3/4" lower in the rear and 1/2" lower in front. Since the Level control has a range of about an inch in it's assigned "proper height" wherein it does not lower nor raise the vehicle, it may or may not adjust the level when fuse is reinstalled and key is on. (this "dead spot" in the system prevents constant adjustment by the system. In addition, there is a delay in the system for activation to prevent constant inflation and deflation while driving down the road. For GM's it's about 20 - 30 seconds of the system seeing an overly high or overly low vehicle)

4) measure the rear TV height
5)reinstall fuse and turn key on....wait a minute. IF the system just "burps", be on your way and have fun. If it turns on for more than say 10 seconds, wait for it to shut off and measure the rear TV height. If it rose 1/4" or less, that doesn't change WD too awefully much. Again, have fun.
If it rises more than 1/4", you should add a little additional WD, and start at step 3 again. (Note: you can start again by leaving key on, use the tongue jack to raise the rear of the TV and AS tongue enough to fake the level control into releasing it's air. You'll hear the hiss. Now, pull fuse, raise tongue jack and take in a link of chain, or add one notch of head tilt, etc. Reinstall fuse, key on and repeat step 4)

I only have to repeat this whole process whenever changing TVs, with any significant change in load, or about once a year to compensate for creaping weight gain.
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Old 03-13-2012, 10:53 AM   #15
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The Air Suspension in the Grand Cherokee is a German designed and built, totally different kind of system from any I have ever seen. It is on all four corners of the vehicle, not just the rear. It levels the entire rig. It can lower the whole rig for ease of entry and exit. It can raise it for rock crawling (remember it is a Jeep). I think, but am not entirely sure it will even re level the car when stationary, that is I think I have seen it move when I was out of the rig. I have never heard any compressor running. When it raises from the lowest position used for ease in entry and exit, first the rear will come up, then the front, then the rear, then the front, all done in about half inch increments.

What I was hoping for was someone who had run into this on another Grand Cherokee, and had figured it out, or had seen some information from Jeep itself about how you were to hook up the (required by the manual) WD hitch system. Not all of the 2011 and 2012 GC's have the system, only the Overlands and up trim lines. But there have been thousands of them sold, so others must have run into the issue. A net search on my part has not run across any real information.

As I mentioned, I only have one 1000 mile trip towing on it so far. I had my 20' Argosy and even with essentially no tension on the spring bars of my hitch, it was exceptionally stable and rock solid as a tow vehicle. But I am still uncomfortable not knowing what is going on and what could happen in an emergency situation.

I thank everyone who has offered suggestions. Unfortunately this system is unlike any other and thus the ideas don't fit the specific thing that Jeep designed. If you do find any information anywhere about this Quadra Lift system, let me know.
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Old 03-13-2012, 11:20 AM   #16
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Although you will need to find the operating characteristics for this particular vehicle...maybe from Chrysler themselves, I think you will find the tweaking for proper WD will be very similar. I know nothing about the new Jeep system, but they are not the first to have air ride on all four corners (1958 Buick Roadmaster, among others...Citroen in the 1960s had it). What will be unique is the software and operating modes which you may encounter during normal towing situations.

I believe, you will find a compressor and level sensors though.
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Old 03-13-2012, 01:35 PM   #17
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Although you will need to find the operating characteristics for this particular vehicle...maybe from Chrysler themselves, I think you will find the tweaking for proper WD will be very similar. I know nothing about the new Jeep system, but they are not the first to have air ride on all four corners (1958 Buick Roadmaster, among others...Citroen in the 1960s had it). What will be unique is the software and operating modes which you may encounter during normal towing situations.

I believe, you will find a compressor and level sensors though.
I had one of those 58 Buick Roadmasters.

It had a fanastic ride, when the system was working.

In the morning, the car would typically have a 'lean: to one side or the other.

In all, 29 air bags were replaced before the cause of the problem was discovered.

Sort of unheard of, but the compressor had too much of a punch, everytime it cycled, which in turn caused a bag to ultimately fail.

The fix was to remove that system, or keep it and pay for all the bags.

That car needed a new bag, almost every week.

Oh well, we enjoyed the ride while it lasted.

Andy
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Old 03-13-2012, 02:28 PM   #18
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I had one of those 58 Buick Roadmasters.

It had a fanastic ride, when the system was working.

In the morning, the car would typically have a 'lean: to one side or the other.

In all, 29 air bags were replaced before the cause of the problem was discovered.

Sort of unheard of, but the compressor had too much of a punch, everytime it cycled, which in turn caused a bag to ultimately fail.

The fix was to remove that system, or keep it and pay for all the bags.

That car needed a new bag, almost every week.

Oh well, we enjoyed the ride while it lasted.

Andy
You, Sir, are exactly correct! Most of them were disconnected or removed. I found one in IMMACULATE condition for $3500 back in 1986. I had 2 small children and a third on the way, didn't have any extra$$$$. UGGGGG! Wouldn't that make a SWEEEEET vintage AS puller now!

Trivia…….That car had the most chrome plating of any car in automotive history…..28 pounds!
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Old 03-13-2012, 07:00 PM   #19
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JEEP Grand Cherokee Quadra Lift

With the QL system I'd spend part of a day at the closest CAT Scale Locator (Lewiston or Missoula; want cross-reference quality values for any other US location in the future.)

I'd want to start a logbook of weights and adjustments, with accompanying photos.

The scale allows me to:

A] Play with WDH combinations. Since it'd be good to get all the numbers anyway (empty & loaded; TT & TV plus separate TW) one would be well ahead per all WDH questions.

1 - (Include published weight per DODGE)

2 - TV; empty but for driver, full fuel (and permanent additions)

3- TV; loaded for travel

4 - TT: empty but for full fresh water & propane (and permanent additions)

5 - TW

6 - TV & TT; hitched, but no WDH application

7 - TV & TT; hitched, with WDh application

IOW, there is not much of a way to find out how the thing works without scale weights.

We know -- according to current truck/SUV practice -- that we want the FA to return to the "laden, unhitched" value once the WDH is set; and the question remaining is how much is on the RA and the TT axle.

It might be that the old 1/3-1/3-1/3 "rule" works for this combo where FA, RA and TT wind up about the same.

Andy can clarify, I believe it was an FA/RA split of around 10% difference between those two axles once WDH adjusted, with the "extra" weight preferably on the RA (and the TT sort of falling where it will) as one is not ever perfectly going to get the three-way split.

B] The second item of great worth is tire load. Pressures are best set (towing or solo) according to load. And it can take a bit of experimenting to get those numbers. Since this is -- at present -- a bit of a weirdo, tire pressure is that much more important. It will be the "base" of how this rig feels short of the "best" WDH adjustments.

Ideal inflation pressure, according to tire engineer Barry Smith, will be found (paraphrased):

After steady state driving of 1.5-hrs; where the pressure rise is no more than about 5-psi after checking overnight cold temp pressure.


It is not max sidewall pressure, it is not max vehicle manufacturer number (although it could be either), and it is certainly not the solo value. One can come in quite high, and ideally one is spot on for best tire life, handling, braking and fuel economy. Too high is not good (and too low terrible).

See Barry's Tire Tech

I'm going to see if I can find anything on the GC. What's the vehicle spec? (A GC Turbodiesel is on my short list of "ideal" TV's).

.
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Old 03-13-2012, 07:33 PM   #20
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I see you've asked this question, here, and it is where I would start.


Also, from Down Under: http://caravanersforum.com/viewtopic.php?f=2&t=20882
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