I'm installing my Gc/ konirace set up. Let say i'd like to put 15x9 all around... I'm gonna have to raise it up enough to clear...

I was wondering what happen when you raise it up until the spring start to be compress... Is it a good thing or bad thing? Is there any way to avoid the preloading by setting the coilover sleeve on the lower perch? I'm tired and confuse and need help on this...

 

Setting the sleeve on a lower perch will not avoid preload. You will simply have to move the collar further up to compensate and result in the same amount of preload for your desired ride height.

To avoid preload, you will have to get stiffer springs. Those will require less/no preload to get the ride height you need.

Longer springs will require the same preload to get your ride height, the only difference is that your collars will be in a lower position.

BTW: Having preload does not change anything from a handeling point of view. It just makes it very difficult to adjust ride height. You will probably need a wrench of some sort to turn the collars...

 

ok let's say I got 8''/500lbs in front... What your saying is that I would need some higher spring rate coil to compensate the weight of the car that will sit on it back on the ground?

How much compression a 600 or 700lb coil would less compress compare to a 500lb? Is there any formula to calculate this compression without having to try it every time for each corner?

Finally, Is GC selling a kind of "hook tool" that would aloud me to turn the collar when the coil start to be compress?

 

If you can access the spring while the car is sitting on the ground, then you can measure the length of the loaded spring and then calculate what the length would be with other spring rates.

A 600 lb spring is 1.2 times heavier than a 500 lb. spring. That means it will compress 1.2 times LESS than a 500 lb. spring with the same load. If the 500 lb. spring is 6" long (1000 lbs. load, compressed 2"), then with a 600 lb. spring that same load will only compress it 1.67". So you could take 2" and divide by 1.2, and that will give you 1.67". A 600 lb. 8" spring with a 1000 lb. load will therefore be 6.33" long.

If you CAN'T access the spring while the car is on the ground, you can still calculate loaded spring length, but you'll have to know your car's corner weights and also take into account the motion ratio. On the front end of a Civic or Integra, that ratio is about 1.5 (the wheel is about 1.5 times farther from the LCA pivot point than the damper connection point is).

NOTE: preload does nothing when the car is on the ground and the springs are loaded. The loaded length of the spring REMAINS THE SAME regardless of preload, unless the preload amount exceeds the load placed on the spring. What will happen is that when the suspension is unloaded, the tire will leave the ground sooner with increased preload. This can be dangerous as it could make it easier for the tires to lose traction or lift a tire off the ground around hard corners.

Also note that trying to force the spring perch higher and preloading the spring will most likely damage the spring's coating on the bottom surface as well as damage the anodizing finish on the spring perch. If you ever drive the car when it rains, water WILL get caught up between the bottom of the spring and the perch, and if the finish is damaged it can start to rust the spring coil wire.

 

How high are you trying to make this car? I've got 400/250 springs on my civic, and I don't think I'de have any trouble hitting original ride height before the coils start preloading...

 

I don't really want it so high, it's just that when I raise up the collar until it start squeezing the coil between the collar and top plate (no more gap), the car is kind of low. The gap in between fender and tire shoulder is about 1/2 inch...

Trying to raise it more is pain in the *** cuze I have to pstart preloading the spring and preloading 500 or 600lb is not that easy...

But thanks for all the good info about calculating formula... That car is going to be corner weight later on this summer... I have to take out abs and A/C first...