My 1978 244 sedan is great around town, but once her speed gets up to 50+ mph, a distinct and worrisome wobble shows up in the steering/suspension.

Basically, any irregularity in the road surface or any kind of side wind will cause the car to wallow back and forth and shift slightly from side to side. Steering at high speeds on curves, on rough pavement, or in windy conditions has become a real struggle. This is especially pronounced on curves, and I'm really worried about whether my control over the car will slip at the wrong moment due to some part giving out.

I had the car checked out by both a Volvo-only garage and a separate tire/suspension specialty shop after I bought her back in March of this year. The front steering rack has been entirely replaced, there are four brand-new identical tires, and the suspension was aligned at the same time as the tire purchase. The car will drive straight just fine at lower speeds. There were no other repairs or major replacements indicated by either shop concerning any part of the steering, suspension, or tires. The problem was present when I purchased the car, and didn't improve with any of these repairs. It doesn't matter whether I'm braking or not. The above-mentioned road conditions are what matters, so I don't think this is a brakes issue (the front brakes were also redone and the back brakes check out OK).

I recently had the epiphany to hop onto each of the corners and see how much "give" each corner had compared to the others. The left front and right rear corners don't bounce very much; the suspension there feels pretty tight. The right front and left rear corners have a lot more give and bounced a lot more when I tested them. The car was totally unloaded when I did this test so there was no load to skew the outcome.

I think this may be a suspension issue, but from what I've read on this forum, it might also be a steering column or steering alignment issue.

Is there anyone here who has some perspective or experience with similar problems? Thanks in advance for the help.