I just got back from a great week on vacation, looking forward to two more starting on the 4th. As some may know, I normally drive an Aztek, and am quite happy with it. For towing to the local ramp, less then a mile away in my subdivision, I have no complaints. It doesn't, however, cut the mustard on long trips loaded up to camp. This year, I borrowed my dad's '98 Astro, and was much happier. It's clearly built to handle the towing, and I had a lot less stress driving.

There was one issue, when I hitched the boat up, I had major sag on the van. It was close to bottoming out. This happened before any gear went into the van or boat, so it wasn't any better when we loaded up. I noticed a fair amount of fishtailing going on that I NEVER experienced on the overloaded Aztek. When changing lanes or getting passed by a large vehicle, I could feel and see the trailer swaying. Also had a lot of bounce in the rear end going over anything bumpy.

I'm looking for opinion on my issue here. My first thought was light tongue weight, but I seriously doubt that's the case, particularly with the major sag going on. I wonder if bad springs or shocks could be doing this. I've got two weeks to get some work done, but I don't want to throw money away. HELP!

You have a rear suspension not at all designed to carry whatever tongue weight your boat puts on it. Plain and simple. Bad choice for tow vehicle.

Weight carried in the vehicle (persons in a van) is dispersed much more equally to both ends, not hapening with 300 pounds on a trailer hitch 4 feet aft of the rear axle.

"leverage"

Fix is stronger springs, coil-over shocks, air shocks, or air bags.

The tires on the van at max capacity? A lot of sponginess can be fixed there.

Otherwise, it need new springs and/or shocks. Or go with the airbag system to raise the bottom out level.

Shocks/springs would be better.

Neither is a great tow vehicle, but the Astro should tow your 19 footer ok. My guess is your hitch ball is too low, allowing too much weight on the tongue. Try reversing the ball to raise the level of the tongue and put more weight on the trailer wheels rather than the vehicle.

Oops, you're going to tell me you used the bumper hitch-ball hole, aren't you? Does it look like the trailer was level when attached?

That era of GM vehicles had soft rearends. Even the suburbans from the era sag with modest weight.

Troop made a good point. Make sure the trailer is level.

The Astro should tow a 19 foot boat just fine, and is known to tow much more. I think D-Rod is dead on, not an uncommon occurrence.

I'm not a moron, it does have a receiver hitch, and without the sag, the height would be good. With the rear end low, the trailer is pointing down just a bit. Not ridiculous, but a bit.

I thought about new springs, and air shocks. I hadn't thought about the coil over shocks, and don't know much about them.

My thoughts on the air shocks are that it's a bandaid. Shocks shouldn't be carrying load, right? Just helping with ride.
(On the other hand, why does GM do the air shock to adjust ride height on most of it's SUV's?)

I think beefier springs are the best bet, but I don't think I'll like that bill. What's the pro-cons of the coil over shocks?

Thanks for the advice so far.

See if it's springs or shocks. Try the bounce test. Without the boat attached, start "hopping" on the bumper. Get the van rocking up and down. It should recover drastically after one bounce. It should NOT be moving after 3 bounces. If it's still bouncing up and down, the shocks probably need replaced. If it recovers, you probably need springs.

CNY might have better ideas.

casualboater, I did not mean to imply anything negative. I've seen lots of stuff towed with bumper-balls, and you did not mention which type of hitch so I did not want to make that assumption.

Well the best thing to do is measure the ride height of the vehicle, unloaded and see how it is compared to how it should be. If the ride height is lower than it should be even unladen, then the rear springs have sagged and should be replaced. Common on older Jeep Cherokees, you see a lot of them sitting low in the rear, and all kinds of suspension mods are available for them. I bet some company makes a heavier duty spring for those vans because they were in production a long time. If the springs are not sagged but the tongue weight causes it to sag, first measure the tongue weight and make sure it's in limits for the weight of the boat and trailer (usually 5-7 % of the total weight). If your tongue weight is correct, and you get sag, you can go to a heavier duty spring but that can make the unladen ride rougher. I used a set of Air Lift air bags in my 98 Jeep. They fit inside the rear coils and make a huge difference towing. Unladen ride is unaffected, you just run enough air to keep the bag from collasping. I would not use air shocks, because shock mounts are not designed to be weight carrying. Go to either Air Lift's or Firestone's website (their product is called Ride Rite) and do some reading. If you can't or do not want to use a WD hitch, it is the only other way besides heavy duty springs, and a product called Timbrens, to level the vehicle.

Might want to put a set of cargo-coils on. They are coil springs designed for towing.

The van does have some sag unladen, I'm fairly certain the springs have issues. Short of complete replacement, how about adding a leaf helper spring? I looked at them today at an auto parts store, it's certainly within my ability to do myself. I was contemplating adding the helper spring and putting in a good set of shocks, a Gabriel utility or truck shock.

I did look at the coil over shock for this van, but I don't think that's going to do it. I'm planning to call a spring shop this week and get an estimate on replacements. I'm hesitant to put a bunch of money into a 10 year old van, particularly since I don't own it! I can borrow it when needed, so I don't mind some investment, but I just can't throw a bunch of money at it.

Whatever you do, do not use it as-is. The swaying is a sign of dangerous instability and may cause you to lose control unexpectedly.

Helper springs will make a difference. Go to the rv.com forum and see what those guys use. They tow alot of weight and many have similar vehicles.

You are exactly correct.
Springs (coil or leaf) support the weight. Shocks control the bounce. They are not supposed to be weight bearing.
As to why GM does use the air shocks on their leveiling suspensions? I guess because they can. But I eliminated my air shocks on my Montana van.

A very stiff "overload" spring seems like a good idea in your case. You wouldn't get the stiff harsh ride of new heavy duty springs, but when you put the weight on, the overload might stop the squat.

I've narrowed it down to two options now they are:

#1 Put on a set of helper springs, like these, and a good set of utility or truck shocks.



#2 I stopped by my local shop today, place I trust, and he highly recommended the coil shock. Said the shock mounts for the Astro were bolted to the frame, and that he's done this fix on several trucks etc. with good results.

Ironically, the cost of the two options is about the same. I'm really leaning towards number one, but I wanted to check with you fine folks before I fork over the cash and do the work.

I like the helper springs because they do not alter the ride of the vehicle unless you have a load on it.

I have no experience with the coil-over shock conversion so I have no opinion there.

I think I like the helper spring option better. However, what is the rating the helper? Is it enough to make a difference?

Have you considered that you may have too much tongue weight? That can cause sway just as much as too little weight. A 19' boat/trailer should only have around 300 pounds of tongue weight max...Grab a friend who, along with you, weighs a total of 300 pounds or slightly more. Both of you get in the back of the van and have the wifey measure how far down the van settles. The boat shouldn't settle it down any farther than YOU do. If so, it may be time to adjust your bow stop---

That said...

Coil-over shocks are okay, but you're still adding stress to the shock mounts, just like air shocks. IMO your safest bet is to add the helper springs. How much they'll help, no clue, BUT they're functional and won't contribute to breaking anything like air or coil-over shocks might. Those pictured are 'half' springs, that mount under the leaf (as shown on the corner of the box)...I've seen 'full' length helpers, but they might not be available to fit an Astro...You may consider finding some that mount ABOVE the leaf, like this:



--I have no experience with either, but from an engineering standpoint, it just appears to me the above-the-leaf style MIGHT be more effective at preventing leaf-sag...

I think the bigger the better!

It's adjustable, depending on how you mount it, to 1,500 lbs. I imagine that will probably do. I checked out a set like FR showed, I think they were good to 1,000 lbs. There's also another set good to 2,000, but the Astro has the axle under the spring, which would require removing the axle to install, no thanks.