Grand Cherokee & Weight Distribution Hitch

[GoldDog]

I have been trying for awhile to find out exactly what sequence to use when setting up my weight distribution hitch with the Jeeps Quadra-lift suspension.
I asked the service dept and they said if I ask 10 people, I'll get 10 different answers. I then asked Jeep/Chrysler and here is their reply.

"Thank you for contacting the Jeep Customer Assistance Center.

Our records indicate this vehicle was equipped from the factory with
Quadra-Lift Air Suspension.

The Quadra-Lift air suspension system provides full time load leveling.
According to available information, the system should be in the Normal

Ride Height Mode when installing a weight distributing hitch and
setting the vehicle up for trailer towing. Allow the system to
auto-level and then set
up/adjust the weight distributing system accordingly.

Please refer to the vehicle owner's manual for details on how to
properly operate and maintain your vehicle....."

[jsallman1]

This is a bit of a guess, others might have better advice here.

Since you probably cant go on the difference in the height between the top of the front tire and the wheel well due to the auto leveling to judge if you have the proper tension on the WD bars, I would secondarily go to scales. Find a cat scale, weigh your car front and rear axels without the trailer, and then put the trailer on, adjust the WD bars until the front axle is close to the unloaded axle weight, then you will know you aren't taking much weight off that front axel adversely affecting tongue weight. Your manual might say if you should return 100% of the weight to the front axel or not.

You can see some of my cat scale results here (and note I did actually get the measurements between the tire and wheel well back to the unloaded measurement), I may need to actually add some more tension to shove a few hundred more pounds to the steer axle. http://www.jaycoowners.com/forums/f3...rip-31200.html

Scale prices aren't bad, I think i did 3 weighs for $14. CAT Scale Locator | CAT Scale can help you find one.

[ttavasc]

Originally Posted by GoldDog

The Quadra-Lift air suspension system provides full time load leveling.
According to available information, the system should be in the Normal

Ride Height Mode when installing a weight distributing hitch and
setting the vehicle up for trailer towing. Allow the system to
auto-level and then set
up/adjust the weight distributing system accordingly.

I have the 4-corner air suspension on my RAM and had the same question regarding the proper way to hitch up. I suspect that your suspension will probably behave the same way mine does. I was trying to set mine up and adjust it per the hitch manufacturers instructions with the suspension active. Even though it seemed to be adjusted properly once I got down the road a short bit it just didn't feel right.

I finally found what for me was the right advice on a RAM Cummins forum - which is essentially disable the suspension before dropping the coupler on the ball and adjusting your weight distribution. After you've adjusted the weight distribution then re-engage the suspension and it should have little work to do. If you are using wheel well measurements to adjust your weight distribution make sure you take those before and after while the suspension is still disable. On my RAM the suspension is disabled by entering into "Tire Jack Mode" via the UConnect console. There should be something similar on the Jeep.

One other thing I discovered - normally you adjust the ball to be slightly higher than the coupler when the trailer is level and allow the tongue weight to bring it down. With the air suspension I had to drop the ball down so that it was about even or just a wee bit lower than the coupler when the trailer is level. This prevents the trailer from ending up slightly nose high as the air suspension will lift the rear up to the height it was before the tongue weight was added - essentially returning the ball to the above level height it started out at.

This procedure works very well on my setup. I continue to disable the suspension every time I hook the trailer up now and I'm getting consistent results from the weight distribution adjustment. I am getting 100% FALR (verified at CAT scale) and the trailer is always level regardless of what the tongue weight is - mine varies from around 425-475lb depending on how the trailer is loaded.

Hope that helps - and good luck.

[GoldDog]

Thanks for the info ttavasc.

[ttavasc]

A couple other things I should mention - you might want to disable the suspension before unhooking as well. Since these are active suspensions even if the vehicle is not moving or the engine is not started I'm finding it a whole lot easier to do anything hitch-related that affects the weight on the rear with the suspension disabled. I'd also recommend disabling the suspension if you don't plan to unhitch after arriving at a destination to avoid unnecessary adjustments from occurring - especially if you are going to use the tongue jack or stabilizers. We do this on occasion when traveling longer distances when we want to get an early start the next day. If you don't you may find the suspension trying to make adjustments and putting stress on the trailer when the tongue jack/stabilizers are done.

[GoldDog]

Excellent info.
I found to disable the suspension on the Jeep, I hold the up and down buttons down at the same time for about 10 seconds.
I also lowered my hitch one hole and that made a big difference in keeping the trailer level after turning the suspension back on.
Thanks! Next stop will be the scales.