I have no clue what you're talking about. There is no setting or tuning the springs, they're just springs that seat onto a threaded tube. This isn't some race suspension setup which can have independent adjustments for spring preload and ride height. Those adjustments don't exist on your car. All you have is a ride height adjustment, which does nothing to change any aspect of the spring. You're just making the strut body longer or shorter with the threaded tube. That's it.

Preload doesn't matter at all in this case, unless you've preloaded the spring so much that the weight of the car still can't overcome the preload (I can't imagine how that would happen). Even then, if you've preloaded the spring that much, the car will sit very, very high, and when you lower the car you're removing that preload. It really doesn't matter how much preload you begin with; once you get to the ride height you want, the spring is always going to be in the same place on the spring perch regardless of where it started.
The spring has a fixed change in length for the force you apply to it (in this case the vehicle weight) and you can't change that.

Basically, what you think you did is not actually possible.

Put it this way: If you crank the spring perch all the way out to the point where the spring is no longer preloaded when you put the cap on, then install the assembly on the car, then raise the ride height, you've just preloaded the spring the exact same way.

All the threaded sleeve does is change the length of the strut in relation to the fixed length of the spring, and it does absolutely nothing to change the spring stiffness or anything else.

 

when i did the job, there was no stopper and the top of the strut had about 3/4 of an inch or more sticking out on top. it was preloaded on a press and the spring was over compressed. as a result, every time i hit a bump, the strut took the entire bump.

i mean, i know ur an expert and all so i wont argue with you, but i know when i got that problem fixed i never had the problem again.

 

I still don't see what you're talking about. If you had that much preload, the car must have been really, really high off the ground, because the only way to get that much preload is to move the perches up the sleeve quite a bit. I'm assuming that you lowered the ride height after that, and then the preload would have been less. If you somehow permanently deformed the springs, you would have moved the perch upward to raise the ride height back to where you wanted it, which would then give more clearance for the strut to travel. If you damaged the springs, you would have had to buy new springs to fix the problem.

Looking at the charts floating around the webz, it looks like Ground Controls are usually roughly 380 lbs/inch front and 280 lbs/inch rear. So figure you have a 2800 pound car (guessing) with a 60front/40rear weight distribution. That would mean about 840 pounds per front spring, or about 2 inches of static spring compression (car sitting under its own weight on the ground. That means that you would have had to compress the springs 2 inches with the spring press to preload them when the car is sitting on it's wheels on the ground. Anything less than that and you have no preload. That's probably a bit off because of motion ratios in the suspension, etc., but you get my drift..

I'm just completely lost trying to figure out what you think you did. Did you use the wrong springs or sleeves on the wrong end of the car?

 

GRs are just OEM replacements as pointed out before. Koni Yellows are a better option when running lowering springs.