1970 Cutlass.....Heard a recommendation to just switch upper control arms to get improved ride...… very economical approach..... does it make sense? Do lower control arms impact the ride much? Will changing just the uppers to tubular make a big positive impact?

Thanks

 

Whoever told you that is unclear on suspension design.

The lower arms carry the weight of the car and locate the spindle in all three axes. There's a reason why they are so much larger than the uppers. The UCAs only carry loads parallel to the road surface. Changing the UCAs will do nothing to "improve ride". Now, if you plan to change to taller spindles or tall ball joints to correct the A-body camber curve problem, then different UCAs are required to permit you to properly align the suspension. The taller spindles require shorter UCAs to get enough adjustment. Note that you do not want to use shorter UCAs with the stock spindles.

 

Thanks Joe

 

My 71 uses a combination of UMI uppers with a 1/2" taller ball joint with stock lowers that I rebuilt with new rubber bushings and ball joints. This along with 1" lowering springs and UMI sway bars has yeilded me a nice, compliant ride with an better (even if not technically great) camber curve and additional positive caster improving steering feel. I surely have left performance on the table by not replacing my lowers, but the tradeoff for harshness of full poly on the most crucial pickup points, as Joe explained above, wasn't one I wanted to make. I will say that the car now is a lot of fun to drive and a vast improvement over where it was, will hit the corners hard and is butter smooth on highways.