1973 Dart Swinger Drum to disc

I’d never go anything less than 1” bars on the street. I ran 1” bars briefly on my duster, even with just 225/60/15’s and the blue Monroe shocks the ride was still pretty soft. I’ve been running 1.12” bars on the street now for years, with Hotchkis fox shocks. The ride is similarly to a modern performance car. The factory torsion bars are only ~100 lb/in, most econo box commuter cars are more like 200 lb/in nowadays. Which is what the 1” bars are. The 1.12’s I run are 300 lb/in. My set up is probably more AutoX than street, but, I use it as a street car. Hell I basically use it as a commuter most of the year.

Remember the stock torsion bars were for bias ply tires. The lack of traction also meant lower wheel rates. Improve the traction of the tires and you transmit more force to the suspension, which means higher wheel rates to deal with those additional loads. Even the basic all season radials most run on these cars have a ton more traction than the old bias ply’s did. And some of it was the style at the time, soft floaty suspension was the thing in the ‘70’s. These cars were massively undersprung in the front from the factory.