does it handle better with the upgrade ATR springs ? did it lower the car with those ?
It already handled very well due to the Herb Adams/ Moroso sway bars on the car, 1 5/16" solid front w/ spherical rod ends instead of end links. 1 1/2" solid rear attached to the lower control arms.
With the ATR springs (stock height) I felt the front was just a little soft even after I installed bilstiens on the car, as compaired to a new Trans Am at the time.
I wanted the car to follow the dips better with no float.
After many, many hours of searching I found some very educational posts by charlie f1, jdpolzin and scot w (GNS performance).
It seems that the stock springs sag about an inch over the years, so installing 1" lowering springs make it set the same as it does now.
I have since sold the ATR springs and installed the UMI performance 1" lowering springs, 600lbs front and 130lbs rear (still in the air for other upgrades and maintenance.
Just for reference the stock TR springs are 421lbs front and 122lbs rear. (Edited rear spring rate, was 118)
ATR (Applied Technologies and Research, now out of business) didn't make their spring rates known, but compairing wire diameter to the stock and UMI, I'm guessing 540- 550lbs front and 125lbs rear.
I'm sure the ATR springs had sagged a little as well.
I am looking forward to neutral steering again, I had 255/50-16's all around with the ATR springs and could slide through curves with the front and rear sliding equally, very easily controlled.
When I went with 17 in wheels I put 255/40-17's front and 285/40-17's rear and have had oversteer (rear sliding more). The stiffer front springs will hopefully even things out and will firm up the front.
This is what the car looked like with the ATR springs.
Stock springs I have.