On my 70 Chevelle here recently it had developed a wierd driving characteristic. The best way I know to describe it is if you stood the car straight up on the back bumper with the front bumper to the sky; it looks and feels like the way a penguin walks or "waddles." What the heck is going on?

It seems like it will come and go, but i can make it go away if I accelerate or if I let off the gas completely it will go away. Seems like several times a bump in the road is what causes it. I you let it keep going and I dont do anything it will get really violent and swaying back and forth really hard.

Any ideas or suggestions? The only idea I have right now on is to go ahead and start replacing bushings in the rearend until I fix it.

sounds like you've got loose rims or egg shaped lug nut holes !!!

That was the first thing that popped into my head as well Mark. Could also be bad shocks or bearings. Check the lug nuts. If that's not the problem, Have someone follow you and see what the tire is doing. If it starts bouncing, its the shocks. If it wobbles, Check the bearings.

Both of the above problems could be the cause of your waddle if it happens on all road surfaces. If not, tires that are excessivly wide may cause the problem you described on some road surfaces. On some surfaces the wide tires can have a problem tracking because of the striations or wear patterns on the surface. They may wander back and forth a little trying to find a track to run in. Feels like waddling. I have the same problem with my Vette on certain highways, especially those where trucks have worn a slight depression in the surface. The tires may move back in forth in those depressions causing your problem.
Mike
'70 hardtop original owner

mine did this real bad since i bought it and when i replaced the shocks, i discovered that the rear had 2 different shocks - 1 was about 2 inches longer than the other! and then on the opposite front corner, my spring is way softer and sagging versus the other side. so for me, 4 new shocks helped ALOT. bushings and springs are on the to-do list - but heater core first, so it's even driveable!

A few other things to look for. A tire with a "ply separation". That will show up as a lump on the tread surface. I doubt this one because usually they are permanent. Nothing you do will cure it except a new tire. And they always cause a waddle regardless of speed.

Possibly a bad tie rod end or idler arm. You don't specify the front or the rear of the car as the source of the waddle but MOST "waddles" emanate from the front end. Anything loose in the front that allows one front tire to run out of line with the other and is loose will set up a waddle that will usually only go away if you slow down. What happens is the "Gurney" effect where the loose wheel starts describing rapid "S"'s. As you can well imagine that will feel like a "waddle". I have seen both bad idler arms and tie rod ends cause some pretty violent motion.

Possibly but less likely would be the inner tie rod ends where they attach to the center link. Best way to check these components is to get under the car and have a friend turn the steering wheel back and forth while you look for anything loose.


If the waddle is being caused by the rear end and is not caused by loose lug nuts or a "ply separation" then I would advise not driving the car until you thoroughly inspect your rear end linkages.