Dorendla

I have a 69 coupe that sways at higher speeds. Can one of you fellows give me a couple of keysuspension areas to check (and how to check)? My approach is to look everything over fresh but here is some info that could help:

What I mean by "sway" is that I get a sensation similar to when you land on a runway in a big airplane. When the plane makes contact you feel that shifting back and forth for a few seconds as the plane settles down from high speeds. It is exactly like that.

A long time ago I did a new steering box and pitman arm, and have done a ball joint (actually it could be both), stuff like that. I never noticed an issue. The springs and shocks were the last major work, and I seem to have inherited the problem after this. I did immediately get an alignment after the swap and still had the problem. I actually went back and told them to look at the alignment again and check the suspension. They didn't see anything wrong.

I've heard that these cars in storage can just sit and end up with issues- things coming loose, or pressure just wearing at them. Someone also suggested that air might be coming in under the car since the front end is higher now. That sounds kind of hard to believe, I'm not going THAT fast. The front end is higher, but it doesn't seem unreasonably high.
__________________________________________________ __________________________________________________ ________________________
https://customrigsmag.com/car-swayin...t-high-speeds/

Vicious95Z28

iTrader: (1)

What kind of shocks did you put on it? Possibly a poor shock choice? I've taken off some used shocks recently that were known to be causing a tire cupping issue. Got brand new shocks for it and right out of the box they didn't have the damping effect that even the old shocks had. Cheap shocks are junk, man. Suspension and steering parts are not a place to cheap out on. Also, you said the car is a '69. It could have one of four or five different engine options for that year so what engine is in it and do you know for certain that the replacement springs and shocks are sufficient? A big block car would've had a spring with a much higher spring rate than a small block or straight 6 car so it's important to know the spring rate on the springs you have.

Rick Dorion

iTrader: (1)

What are your alignment specs?

Rich-L79

Exactly. Especially the toe settings. This is all assuming your tie rods and center link are sound and don't have any play in them.

silversrtman

iTrader: (20)

What kind of tires are you running? That can happen when you run slicks in the rear and street tires up front. I have experienced that same thing while slowing down at the 1/4 mile track. Creepy feeling.

99 Black Bird T/A

iTrader: (4)

I'd confirm the correct air pressure, alignment and tire balance first.

As the prior poster mentioned, what type of tires are on the front & rear? Radial all the way around?

Mixing radial & bias ply tires can sometimes result in goofy suspension effects with some cars. Being a 69 the cars original suspension was designed for bias ply tires.

Radial tires allow the sidewall and the tread to function as two independent features of the tire.

Bias tire consists of multiple rubber plies over lapping each other. The crown and sidewalls are interdependent. The overlapped plies form a thick layer that is less flexible and more sensitive to overheating. Bias tires often provide more of a centered steering feeling when driving on highway at speed in a car designed for bias ply tires when compared to a set of radials due to the overjapped plies.

JoshHefnerX

Yeah, there's a big lack of info on here. I had a 67 Firebird and that thing was rock stable up into triple digits.

Need more info.