Tow vehicle sag

[danlehosky]

I have a 2012 25FB Flying Cloud using a Hensley arrow hitch with 1000 lb bars. My tow vehicle is a 2002 Chevy Trailblazer. I know It's not ideal but it's what I have and I plan on having my Flying Cloud much longer than the tow vehicle so I got the trailer I wanted rather then getting a trailer that matches my existing tow vehicle. Make sense? I am getting about 4 inches of rear sag when the trailer load is on the hitch. I can take some of this out by adjusting the bars but don't want to make the trailer ride to stiff. Would new shocks help? Is this amount of sag normal?
Best,
Dan

[dznf0g]

Shocks won't help. Take sag out by adjusting WD with the hitch. Weigh and measure before and after till you get it dialed in. Use the google forum search function. There is A LOT of reading material on this subject.

[Silver Goose]

Welcome to Airstreaming. As you may know your Trailblazer is rated to tow between 4800 and 6400 lbs depending on how it was equipped. Shocks control the rebound of the axles as you go over bumps and dips. If weight is applied to them, they will compress. If they are worn, they will compress faster than new ones. Air shocks on the other hand employ a bladder and compressed air to supplement the springs to achieve a normal height in the rear. Upgrading the rear springs is another option. I would start by insuring your hitch is correctly adjusted before making any modifications.

Many of us expect our Airstreams to out live several tow vehicles. It is not unusual to buy the trailer you want and then later trade to a TV that is better suited to the task.

A 4" drop in the rear may be telling you the rear axle and wheels are overloaded. Such an arrangement could also underload the steer axle. I would start by making a trip to the nearest truckstop with scales. Fill the tank and have the Trailblazer roughly loaded as it would be when you tow and get a weight of the solo Trailblazer. The scales are segmented so you will get a weights for the steer and drive axles and a total. Now, get weighed with the trailer in tow. The trailer should have full propane and otherwise be loaded as it would be for travel and the hitch adjusted as you have been doing. You will now have new weights for the steer, drive and trailer axles and a new total. The difference in the original and new totals is the weight of the trailer. Now compare your before and after steer and drive axle weights. Ideally you want to see an approximate equal increase in weight on the steer and drive axles.

I believe you will see the majority of the weight is resting on the rear. Now cinch up the spring bars to the point where the Trailblazer looks level and then drive back on the scales for a reweigh. If this gets you where you want to be, you may have to adjust the head height to get the trailer level for towing.

[purdiferis]

Hi Dan, I use airlift brand helpers on my 1500Chevy PU, w/out the pump. Cheap, reliable and easy to install. I just use regular ball hitch.

After reading Gooses comment I am going in to gravel pit and get my weights, good info to have.

Purd

[slowmover]

You really do want to run the full set of numbers via certified three-pad scale (CAT Scale). It takes an hour or so and from there you can start to make adjustments, do some driving, and get things nailed down.

Post the following from manufacturer Towing Guide

TT: ship weight + tongue weight
GVWR

TV: ship weight plus
GVWR
GCWR
FAWR
RAWR
(include door sticker info if different from online or owners manual info.

Then, on scale:

Empty weight both vehicles (fuel & water) with separate TW (optional, but informative)


WDH activated
WDH inactivated

with front axle, rear axle and then trailer axles all on separate pads.

This can be done with the Ron Gratz chart I have posted several times. Just fill in the blanks for the scale work. Post up the scale readings and we can work it out here.

From there -- with these numbers -- your rig can be dialled in as well as possible before you start spending money somewhere. Tires, shocks, etc, can be changed to make a better TV in some instances.

Without the numbers WD is almost futile. The big WDH adjustments are easy (height measurements). The small ones need the help of numbers, but are telling as you run the roads. The H/A hitch isn't as adjustable as a PP, but the numbers still tell where things are "off". A different stinger may be in order, for example.

.

[mojo]

Your hitch weight is listed at 837lbs. Two full propane tanks at 60lbs. Hensley at about 250lbs. Look up the hitch capacity of your Trailblazer and you are probably beyond the limits even when empty. You can pack a lot of your heavy camping gear in the rear of the trailer to offset some of the weight. When you back the car onto the stinger, tighten the WD jacks tight before lowering the trailer jack and then see how much drop you have.

[moosetags]

Ditto to what the other posters have said, although there is one point that I would like to emphasize. Silver Goose mentions "underlaoding the steering axle". This is a significant issue. When the rear of the tow vehicle is substantially overloaded, it takes weight from the front (steering) axle. This diminishes the the steering capacity of the tow vehicle. This can be quite dangerous if an evasive action is required.

You should really consider using your weight distribution bars to get some more weight on the front axle. The steering issue is much more important than whether the Airstream is getting stiff ride. You can do all the other things mentioned to sort out this problem, but I would not tow the Airstream two blocks without adequate steering control.

Brian

[87MH]

Lots of good info here:


Go to this thread for a good discussion:

http://www.airforums.com/forums/f464...xle-46578.html



Below is a summation of about 15 weighs with the Excursion and the '78 Sovereign one morning at a "slow" Cat scale.
Note the load on the rear axle. This is usually the first limit that is busted. The addition of rear "helper springs", air bags, or torsion bars does NOT increase the rating of the rear axle, rather it masks the actual load by removing some of the load from the original springs. Manufacturer rating is determined by many things, brakes, bearings, tires, rims, and springs among them. Manufacturers spend a bunch of money on engineers and programs to determine a safe axle rating...best not to bust the manufacturers rating.