Astro Sway

I have a 1999 Astro that i just took on a trip. It is the most unstable thing i have ever driven at highway speeds! Is this problem common to these vans? At 65-75 every movement in the steering makes the rear sway like you are pulling a trailer thats not loaded right. It sorts of dips and sways to each side. This also happens when passing a semi or being passed. I have so far replaced all tie rods and one idler arm, had it aligned all because the steering seemed loose even before i took the trip. Has anyone had this problem and what did you do to solve it, i have a 4,000 mile round trip coming up soon.

I ad a similiar problem with my 92. The biggest improvement I was able to make was by changing tires. The tires on it when I bought the van had super soft sidewalls. By switching to a "touring" type tire with a stiff sidewall, most of the sway that you speak of went away.

I would agree with the tires. I've had some vehicles that were a joke in a cross-wind. I changed to tires with a 2 ply sidewall, which is much stiffer, and solved the problem.
Also, maybe get under the van and look for a leaky shock absorber. I've been surprised at how bad some vehicles handle with 1 bad shock.

The tires are new with less than 3,000 miles on them. They are Uniroyals with 2ply sidewalls and a load range C.

You could go to "www.tirerack.com" and see how they compare.
What about inflation pressure? Never go above what's on the sidewall, but a couple of extra pounds can help.
And again, look for a leaky shock.

Personally I think the stock shocks and springs are crap, I have the same problem with mine, I have had my van since new and that is how it is, I have changed the tires just cause of wear and that didn't help, but gauranteed its the cheesey suspension.

Ok, these aren't Corvettes, and never tried to be. Double wishbone front is good, and leaf springs at the back are also good. GM tried coils in the back a long time ago in pickups, and went with leaves.
Is the van fundamentaly good? These weigh over 4500lbs.The front ends of these take a beating, and the links in the front do wear out. Maybe the links in the sway bar are worn out. Leaky shocks. Maybe there's 300 lbs on the roof? I've ridden in lots of these vans, and own 1, they aren't a bad handling VAN, but yes, not a sports car. I replaced the shocks in mine due to leakage, and the springs seem to do fine at keeping the bumpers from dragging when loaded or towing. Mine goes down the road rather well, and seems to be an improvement over my previous '81 chev van.

Well we all now they are not sports cars but on some of these vans they are crap and this is not my first one either, with eight people in my van the suspension sucks, it handles like crap and sways like it is going out style, I have had my 2000 from it was brand new and has always sucked with a bit of wieght on it. I have been dealing with astro vans since they first started. Personally I am just going to put heavier duty shocks on mine because they suck and know one can tell me different. So if everything mechanicaly is fine, then cheapest thing is to put some good ass shocks and then see what happens.

Just my 3 cents.

8 people, say 150 lbs each, is about 1200 lbs. Yes, that is a lot of weight. I'm not sure what the van or the tires are rated for gross wieght.
Maybe you should look at installing an extra leaf, or air shocks. I'll check the tire side walls tonight if I remember.
At least it isn't a front wheel drive van.

You might also want to consider light truck tires if it's that bothersome for you. They would have an even stiffer side wall.

I looked at my tires, they're rated for about 1750 lbs each. If the vehicle is balanced, van/gas 8 people would come to about 1450 lbs each tire, so i guess that's ok.
LT tires would be much stiffer. Good idea. Has anyone looked into a rear sway bar for these vans?

Do any of the more recent year models have a rear sway bar? The reason I ask is that my '89 doesn't have one. I've been looking online for a retrofit rear sway bar, and I think I've found a few. (didn't think a rear sway bar was particularly new technology).
I haven't bought one just yet, mostly due to a number of other parts stacked up in the garage waiting for time to install.
My shocks definitately need an upgrade. I'm going to install the fattest rear sway bar I can find. I'll start a new post once I do, and let you know how it turns out.

Some recent and older vans both had rear bars. You might get lucky in a salavge yard.

i have a 88 astro. the front swaybar keeps cracking at the a arm bushing seams..i have replaced it 2 times on this van and 2 times on the last one i had.try some LT tires on the back and new shocks all around.the fiberglass spring we trough them away jcwitlass has them in steel. and they cannot destroy them in shipping.its just not a sports car but nos can make it fly.also i forgot try some wider rims i used rally rims from a g van they look good and are wider then any astro rim.the realwide ones on a pickup look good on the back and make it sway less.

Suspension. I Use The Toyo Ultra 500 With Great Success. Also, Beefy Shocks. I Replaced The Front Steering Arms , Idlers Etc., Because Factory Parts Are Weak. Replacing The Front End Parts Was The Single Most Factor In Alleviating Sway. Most Auto Parts Places (napa) Sell Lifetime Parts - If You Plan On Keeping It, Get The Hd Stuff And Have Your Mechanic Install Them.