Classic/Antique Car Repair: 1976 Celica rear suspension, toyota celica, torsion bar

Question
Goodmorning, I have a 1976 Toyota Celica completly stock.A couple of months ago I decided to change the suspension bushings. I couldn't find OEM bushings so I went with the polyurethane. Since then the car's rear end tends to wonder going over bumps even when going in a straight line, it gets worse around turns. The coil springs are original units about 10 years old the shocks are new but on the soft side. No antisway bar in the back. The rear end is a solid axle with a 4 point set up with a torsion bar.
Any help will be apreciated.
Thank you, Evangelos  

Answer
I would suggest that you go over the installation of the bushings. It sounds like one or more of the bushings is not seated correctly and allowing the rear axle to shift under these conditions. The second thing to consider is that the poly bushings do not allow the rear axle to move the way the engineer designed it. In some cases this makes the handling of the car a bit squirmy. But check everything.
Brad