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Old 04-15-2012, 01:29 PM   #1
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2012 Jeep Overland Air Suspension and WD hitch setup

I have written about the problems associated with the new Jeep Grand Cherokee Overland air suspension system, and how confused I was as to how to make it work with a WD hitch system. Jeep requires a WD hitch when over 500# tongue weights are involved.

So, I finally hooked up, and took my rig to the Idaho DOT scales (100 miles each way, I live in the boondocks) which are left available and on when they are not open. They have digital readouts, so no "tickets" are printed when you are using them when not open.

The rig: 74 Argosy 20' with a new Dexter axle, 16" wheels and Goodrich LT tires, front water tank, full, spare tire in front, behind the propane tanks, One 30# tank full, one empty, older EZ lift/Drawtite WD hitch with 750# round tapered spring bars. 2012 Jeep Grand Cherokee Overland with automatic air suspension on all 4 wheels. No conventional springs at all. System can be adjusted for some ride height variations, but not while traveling and only at slow speeds. System cannot be turned off except for very limited situations, while stationary. It uses a sealed nitrogen high pressure system, but I am somewhat unsure of it other than that. I have found little information on it. I believe it is the same system used on some of the Mercedes SUV's. It is made in Germany from what I understand.

I was most concerned as to how to hook it up with a WD hitch as I had found it to be what I considered to be strange in ride height when I first hooked it up in a stationary situation on not level ground. I thought the Air Suspension system was fighting with the WD hitch and spring bars as to which one was going to carry the tongue load. The Air Suspension will easily pick up the weight of the tongue, and make the entire rig, Jeep and Argosy, look level, even without the WD hitch but what was really happening? When I put tension on the spring bars, where was the weight being distributed? When first hooked up, the total rig did not look right to me, heights etc. So, here is what I have found.

I will tell you the bottom line first: The Jeep with Air Suspension may hook up funny, and look funny at first, but after you tow a short distance, all is well and the WD hitch will get along just fine with the Jeep Air Suspension. The numbers below will show what is happening.

At the scales:

I was loaded as "normal" for a trip, tools in the Jeep, Honda 1000, and other travel stuff. The front water tank full in Argosy and "normal" stuff in it.

1. Jeep solo, driver included:

Front: 2900 Rear: 2800 Total: 5700

Argosy:

Tongue: 680 Wheels: 3480

2. Hooked up, no spring bars installed, Jeep running so Air Suspension is operating:

Jeep: 6360 total (I stupidly did not weight front and rear)

Argosy: 3480 (on wheels, tongue weight transferred to Jeep.

3: Hooked up, 8 links under tension: Note, very little tension on the spring bars. Again, Jeep running so air suspension is operational.

Jeep: Front 2680 Rear 3600

Argosy: 3540

You can see that a little of the tongue weight was transferred back to the Argosy

4: Hooked up, 7 links under tension, Jeep running so Air Suspension is operating.

Jeep: Front 2780 Rear 3480

Argosy: 3620

You can see, more weight was transferred to the front of the Jeep and more back to the Argosy.

Each time I hooked up, the Jeep had to be run to do it's thing and level out. But after it had done that, it is apparent that the weight was being transferred as it usually is with a WD hitch from the rear to the front wheels, and some back to the Argosy.


Other notes and comments: I left it at 7 links under tension, and it tows beautifully. I can see that I might even try 6 links to transfer even more from the rear to the front, and to the Argosy. I have not done that yet.

I also need to lower my hitch ball about an inch, but that requires a different shank, and significant cost. With a single axle trailer level is not quite as critical as it is with a dual axle one, but I do still want to change that shank.

Right now, I can say that the Jeep Air Suspension system will, after set up and running, transfer weight with a WD hitch the same as a conventional spring system will do. The one thing that has to be done is to let it run for a minute or so to sort out the system. Don't be fooled, when doing this on non level ground, as I did when I first got the rig, that there is some problem. It will all automatically sort out when on the level and underway.

I would say it is mandatory to take a trip to the scales to be sure you have enough links pulled up to transfer the weight. With the automatic leveling of the Air suspension, you CANNOT tell what is going on without weighting and seeing that the weight is making the transfer. It looks good, with no sagging, no matter what you do, visually. Only weighing will tell you if you have it hooked up right, and in fact are not overloading the rear and under loading the front of the Jeep.

By the way, the new Jeep Grand Cherokee tows the Argosy incredibly well, like on rails. I am a very happy camper.

The photo is of the rig with 7 links under tension.
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Old 04-15-2012, 02:00 PM   #2
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If you are happy, maybe that is all that matters. But.....you may still wish to shorten your links so that your weight distribution to your front and rear axels is more even. It appears from your photo that the WD bars are not doing much, and the angle of the hitch head should be done more so that you can increase the lifting force but still retain 6 links for wiggle room. You may also improve performance by moving the ball closer to the rear axel. Sometimes it takes quite a while to really feel comfortable with your set up and if you are there already, hair on yea.
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Old 04-15-2012, 02:11 PM   #3
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I hear next year Jeep will release a Diesel Grand Cherokee. Really looking forward to trading up to that tow vehicle. Thanks for sharing your experience with the air suspension.
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Old 04-15-2012, 03:11 PM   #4
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We have a 2011 GC Overland 4x4 and the Hemi V8. We tow a DWR 16 with it. In January we left LA drove to Monterey and came back via Big Sur (we spent a couple of nights there) It was the first time we towed with the GC. We hooked the trailer up, plugged it to the Jeep and drove away. The tow haul mode is sensational and using the the adaptive cruise control we towed up the big hill out of San Luis Obispo and never went over 2400 rpm. On the flats at 60 mph we were turning 16-1700 rpm. On the twisties in Big Sur we could run right at the speed limit while towing, it seemed the trailer wasn't even there. The GC is not economical but while towing I averaged around 15mpg for the trip.

My dealer told me the diesel isn't in the works for the US. The reviews on it from the Aussie car mags are 5 Star
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Old 04-15-2012, 03:14 PM   #5
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SoCal, here's the press release I saw. No word on price or release date:

Quote:
Chrysler Group has announced plans to launch a diesel version of the Jeep Grand Cherokee, and to add 1100 jobs at its Jefferson North Assembly Plant in Detroit, Michigan.
A diesel-powered Jeep Grand Cherokee, which is set to arrive for 2013, will supplement the SUV’s current 3.6-liter V-6, 5.7-liter V-8, and 6.4-liter V-8 engine offerings. Chrysler CEO Sergio Marchionne had previously revealed that a Jeep diesel would debut by 2013 in an interview in October. The engine is expected to be the same 3.0-liter turbo-diesel V-6 offered in Europe, which produces 237 hp and 406 lb-ft of torque. It should be significantly more fuel efficient than the Grand Cherokee’s gasoline engines; in Europe, the diesel Jeep is rated at the equivalent of 28 combined mpg.
Read more: Chrysler Confirms Diesel Jeep Grand Cherokee for 2013, Adds 1100 Jobs in Detroit - WOT on Motor Trend
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Old 04-15-2012, 03:49 PM   #6
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Damn dealer. I had my GC in for an oil change about 6 weeks ago and he said "Naw, the diesel isn't coming to the US."

28mpg combined full size SUV that can pull stumps.
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Old 04-15-2012, 04:14 PM   #7
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Nice picture. If it were me, I'd be trying to get that ball closer to the back of the TV to reduce the leverage that the tongue is exerting on the back axle. I'd also tighten up the chains a bit to get weights on the axles more even. Just a thought.
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Old 04-15-2012, 04:26 PM   #8
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"If you are happy, maybe that is all that matters. But.....you may still wish to shorten your links so that your weight distribution to your front and rear axels is more even. It appears from your photo that the WD bars are not doing much"

Agree with Jim, you still need to move more weight and get the trailer level. Rear end appears low,(level ground?), stinger may need more drop,

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Old 04-15-2012, 05:39 PM   #9
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Jim, Mr toad and Robert: Thanks for the input. The hitch head on this hitch cannot tilt, so that change is out of the picture. On my Reese, it can, and I may get a different stinger for that hitch, as it can tilt. The ball cannot be moved closer to the back by more than a couple of inches at most, and I don't think that is going to change much. It also would require a different stinger. The ball does need to be lower, and that is why the Argosy rear end looks a little low. An inch or an inch and a half lower ball would be nice. Again, once I decide which hitch to use, and which stinger to buy, I can correct that.

I agree, that another link probably would be good to pull up to move some more weight forward and off the rear wheels. I will try it when I hook up the next time to see how it feels. When I can take it to get on the scales again, I can also get the weight readings. I wish I had done that the last time, but I had hitched and unhitched and changed things so much I ran out of steam. The ISP (Idaho State Police) even came by several times but did not stop. I think they were wondering what the heck I was doing at the scales for so long...lol.

So, different stinger allowing a lower ball height, maybe change to my Reese hitch with 750# bars, so the head angle can be changed, and maybe transfer more weight forward with more tension on the bars.

The good news is that the Air Suspension does not fight with the WD hitch system once it is set up properly, and does allow weight to be moved forward to the front tires. That sure was not clear when I first hooked it up in my somewhat uneven driveway, and when the car was not running.
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Old 04-15-2012, 05:41 PM   #10
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The WD hitch that came with our Overlander stuck out the back of the receiver almost 25" more than a normal hitch..

This weekend we balled up to take a overnight trip to a local lake for just a get away trip.. I got a normal reach hitch and the difference in towing was night and day.. I understand the reason for needing to drop a tail gate,, or swing open doors while the trailer is balled,, but for safety, it's not worth it..

Even with a 40mph side wind with the trip home I never felt any tail wagging like before. The basics of hitch and set up is 90% of the battle. It takes time,, and effort to find that middle ground and good scales are important to see if you are going forward or backwards..

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Old 04-15-2012, 06:46 PM   #11
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Great stuff, idroba!!

Thank you for taking the time and in the detail shown in the explanation. We all know that Goal #1 for a WDH is in "restoring" the TV FA to the "laden/solo" weight value, but that'll have to wait for another trip.

I agree with others above. There is room for improvement. And, yes, an inch or two makes a difference on shank length (if it will work in re clearances). It's all little stuff in the end.

Very pleased that it is at a good stage and that there were no real surprises.

The latest Dodge 1500 truck will be coming out with full air ride. Your thread here will be accessed often, even if the systems differ.

Thanks again for the trouble you've gone to.

.
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Old 04-15-2012, 07:54 PM   #12
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I like using this photo - I may not be able to open the tailgate but I'm as close to the rear axle as I can get!

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Old 04-22-2012, 11:59 AM   #13
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Glad that you got it sorted out ...
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Old 04-29-2012, 02:57 PM   #14
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I thought I might update some information on the Jeep Grand Cherokee Air Suspension system and a WD hitch.

You may recall from above that I have now determined that the Air Suspension system does not fight with the WD hitch, and, if hooked up using a highway scale to determine how the weight of the tongue is moved around, you can get the WD hitch spring bars pulled up properly. There is no way to tell the proper hookup, as far as I know now, without the use of a road scale. Doing it visually does not work at all.

I was out on a trip this week and on the return was able to use the same scale that I used the last time to do some more checking. I was slightly higher in overall weight this time, with some more "stuff" in the rigs. It looks like about 150 to 200 # heavier overall.

This time my weights were as follows:

With 7 links under tension:

Front: 2760 Rear: 3540 Trailer: 3740

With 6 links under tension:

Front 2900 Rear 3300 Trailer: 3800

It is obvious to me that I need to pull the WD hitch links up so the second set of numbers is what I have under load. However, since the hitch I have been using does not allow a tilt, I cannot have only 6 links under tension and have enough proper movement in tight turn situations. So, I not only need to change my hitch stinger to allow a lower ball height, but so I can use my Reese hitch head, which can be tilted so more links on the chains can be under tension, allowing more chain movement. This will require another trip to the scales to see where the weights are going, as the bars are a different kind.

A seat of the pants towing observation is that both the 7 and 6 link under tension positions seem to tow about equally well (very nicely). The 6 link might be slightly better and more solid feeling, but it is very subtle.

I have found that there is in fact an "off" position for the Air Suspension, used only when you change a tire, and which turns the system back on at 5 mph. I don't know if it would be of any value on the WD hookup.

I also found that there is an "aero" mode, which automatically lowers the suspension 1/2" over 65, and can also be turned on at any time by putting the control into "sport" mode, locking it at the lower height. I tried this on the scales yesterday, and it did not make any difference in the weight distributions I measured.

So, no startling information here, but I am learning how to dial in an Air Suspension version of the Jeep to tow well.
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