Lowering Springs
 

I’m replacing the springs in my 72 GTO and don’t want the car to raise vs where it sits today so figured that I should go for at least a 1” lowering spring. I did new Bilstein’s last year and the ride is pretty terrible so I figured I should replace the old worn stock springs and go through my bushings. I’m looking at UMI springs because I know they offer a spring package with Bilstein shocks (supposedly special valves for them which I don’t have) and they offer a -1” or -2”, I automatically assume -1” but throwing it out there for other suggestions, yes or no, different spring mfr?

This is my 68 with UMI 1" lowering springs. Photo is from 'Day 1' after restoration so it hasn't fully seated yet

I installed UMI 1" lowering springs on my 71 a few months ago. I've put several hundred miles on it since. Very happy with the ride and stance.

I installed Global West Control Arms and Springs last year and could not be happier. Ride and cornering are excellent.

I’m getting ready to order and still trying to decide if I should order 1” or 2”?

I have a pair of 2" that I had from another project that I installed on my 71. It was way too low for me as I was trying to maintain a somewhat stock look. Check out the pic I posted earlier, the car sits pretty level with the 1" springs. I'm running the 14" wheels also.

UMI 2" lowering springs sat way too low on my '71 Cutlass. They were good to work with and let me exchange for 1" though. Their 2" tucked a 26.5" tire so far inside the fender that steering was very limited before tires rubbed.

Ok, so it sounds like 2” might be too low then. I’ve read that the 1” drop springs usually don’t drop the car if you’re using the old factory springs like myself so I wanted just a little more drop than I have now but don’t want to deal with the issues noted above.

I'm in the middle of a front suspension rebuild on my 66 GTO convertible.
I ordered Global 1" lowering springs. They are 2 1/2 inches shorter than the original ones. I called Global and rep says they will only lower 1 to 1 1/4 ".
I'll have it back together in a week or so, I'll post the outcome. Anyone have any input?

Very common for aftermarket springs to be shorter than the OE springs due to different tensile wire used to wrap the coils, I wouldn’t worry at all about and go with what the mfr says.

It's the difference in spring rate. The coils you selected from Global West will be around 500 lb/in, while the springs you took out of the car are going to be somewhere around 150 lb/in.

The stock springs are necessarily very long because they compress a lot due to lack of rate.

On a linear rate spring it will nominally compress 1 inch for matching set of rate. So if your front end weighs 2000 lbs and each spring has a rate of 300 lb/in, to hold up a 1000 lbs will require the spring to compress about 3.33 inches.

You can do the same math on the Global West springs. At 500 lbs, they will only compress 2" to hold up a 1000 lbs, so they don't need to be as long.

Thanks for the info. It really helps to have confirmation from several people.