The Dodge Challenger Message Board

I swapped in a 440 in a 1974 Rally 318 Challenger and have the stock torsion bars on and a pair of 383/360 bars (0.90", silver marks) I could put on. I am just getting the car together, have a stock rear sway bar on it and a stock front bar to go on soon. I have been reading about chassis setups and a front end heavy car will likely have understeer. In that case it appears that the best solution to getting back to neutral is to play with the rear spring rates, not increase the front, i.e. thicker torsion bar. I contemplating whether to bother putting in the thicker torsion bars. Any comments or philosophies on setting up suspensions on mopars?

If the front end is too soft the rear will oversteer. You have to get the balance right.

Start by fitting the right size torsion bars on the front for the weight of your engine otherwise it will bounce around at speed on an uneven road. 0.90" is still a touch too light even for American soft suspension tastes. However if you don't want to spend money they are a lot closer than the 318 bars.

Then fit the front and rear sway bars and try driving it. Find an open smooth area and drive in a tight circle faster and faster until the front or rear starts to drift. That will tell you if you have understeer or oversteer.

To fix understeer either decrease the front spring rate (not a good idea in your case because the front is already too soft) or increase the rear rate (either the leaf springs or the sway bar)

To fix oversteer either increase front spring rate and/or decrease the rear.

Thanks for the advise Dave. The roads out here are pretty rough due to the weather, so I might need the stability at high speed. Think I'll will put the 383 torsion bars and stock sway bars for this summer. Might even put new shocks on. Maybe this winter I'll rebuild the suspension and do some upgrading.
Tedd