I'm ready for a decent ride. These 800 lb/in weight jacks are stupid on the crumbling roads in my city. The ride is so harsh. My friends tell me that my suspension doesn't even move driving down the road, car just follows the bumps and I believe it.

So in your experience, what is the stiffest spring before the ride becomes harsh?

 

Harsh ride is a relative term, one person wants the “race car” ride, while another finds it unbearable. Are your struts and shocks adjustable? Compression and rebound adjustments are primarily used to control oscillation of the springs and a stiffer spring requires less damping due to less movement from a given weight. Most people will crank up the compression because that’s what “race cars” have. You can tame a stiff spring for the street by finding the sweet spot between bouncing and jarring. As far as the original question, a spring in the 600 - 675 range is a good compromise between Cadillac and Cup Car for a LS 3rd gen. Keep in mind the “relative” statement above.

 

Maybe this is where I'm screwing up.

 

What shocks you running? I ran some global west springs on my 91 that were i think 750-800 lb and i didnt find it that jarring but it kinda depended what i had the shocks set to. They were just 5 way adjustable tokicos. If i kept them on the softer settings they rode pretty well. Im sure a koni could work or a double adjustable viking. I know there was a good difference. Even on my drag car with stock iroc rear springs and 275 lb coil overs up front, if i have them set stiff (medium to high compression and tight rebound) to tie front end down, any bumps are very stiff and jarring.

 

Koni yellow up front (adjustable Rebound only)
Viking warrior in rear (adjustable Compression and Rebound)

I will admit to having my rear shocks dialed up some in Compression because it has helped traction with hard acceleration. But even the front is jarring, just less so.

Roads where I live have been gradually getting crappier and crappier over the years. Now have lots of sharp bumps (heaving, potholes, poorly done repair patches). Sometimes the road is a matrix of this stuff and it just pounds the car.

 

I'm running eibach pro-kit springs and KYB AGX. It's a firm ride but not jarring unless you're on a real bad road

 

I think the Eibach Pro are 714 lb/in