Clattering noise at left rear + swaying over bumps

[white89euro]

Hi Everyone,

Here's a new one for my 1990 Century Wagon. For the past two weeks the car has been making a clattering sound, somewhat like a diver leaping off a diving board - the sound seems to come from the left rear of the car when passing over bumps, cracks and uneven road surfaces. At speeds of 55 to 60 mph on one particularly bad stretch of state highway, the car begins to sway left and right, requiring slight steering corrections - sort of like a dog's wagging tale effect.

I'm thinking something is wrong with the rear suspension. I had air shocks installed about 3 years ago at the rear to create a level ride while towing a camper. Other than that the rear suspension is stock.

The wagging / handling problem has worsened and I think it really isn't safe to drive like that. So I have the car scheduled to be inspected by my mechanic next Wednesday.

Just wondering if anyone else has had a problem like this with their A-body cars.

Thanks!
George:confused:

[85 Holiday]

Uh oh, hope the backend did rust apart...

[Tonglebeak]

Uh oh, hope the backend did rust apart...

I have a similar noise as well but that was after doing the rear disc conversion. I need to look that over one day...

[CieraSL92]

Sounds like the trackbar broke/rotted or isn't securely connected to the axle or body.

Edit: Or one of the brackets at axle or body rotted out. You can actually look yourself if you crawl underneath with a flash light.

[Pontiac6ksteawd]

It could be the rear anchor point rusted out, like the others have suggested. Or it could be that the upper shock mount needs to be replaced from wear. Either way, it needs to be looked at.

[CieraSL92]

Shocks would not cause vehicle sway, perhaps noise but not sway.

[white89euro]

Thanks for the advice everyone. The thing I'm most concerned about is suspension rust. When I restored the car in 2006 I had the entire underbody painted with POR-15 rust converter and then sprayed with rubberized undercoating. Maybe that wasn't enough to save the rear suspension parts though. I think I'll take a closer look at the parts you've mentioned when I can get under the car tomorrow. I've got it scheduled for the mechanic next week Wednesday, and I'll be driving our 2002 Chevy Venture minivan in the meantime. I'll let you know what I find. Hopefully the parts can be repaired or replaced without major metal-work. Thanks again! George

[white89euro]

Hello! Here's how it turned out. It actually was the shocks, and only the shocks that caused the problem of excessive bounce and sway. The Monroe air shocks were worn out. My mechanic replaced them and the car performs normally even on the worst road in my area.

I had forgotten that I had the same problem and the same cause (bad shocks) on my 1988 Pontiac 6000 wagon (fitted with regular shocks). Once the shocks were replace the handling returned to normal.

Hopefully next time I'll remember that worn out rear shocks can cause sway.