What are they? What do they do? How do they work? Are they usable on the street?

 

Weight Jacks are basically spring pertches. There are quite a few uses for weight jacks. You can use them to adjust the ride height of the car, set corner weights on the car, or adjust the roll center height of the car. And because of the way they are designed, at full lock they can make it easier to remove and install springs (do not need a spring puller). They were designed for racing uses, but they are streetable with the right springs.

Here is how the device is constructed and used: There is a steel weight jack screw, a spring bucket or pertch, and a mounting plate at the very bottom. The weight jack is installed below the spring. The bucket itself is where the spring is seated. So instead of the spring being seated on the A-frame, the weight jack spring bucket holds the spring. The spring bucket/pertch can be adjusted (via screwing up or down) for height adjustment. The mounting plate at the very bottom of the weight jack sits in the A-frame where the spring used to sit. When installed under the spring, the weight jack screw is located inside the front spring. There is an adjustment tool you use to to screw/move the bucket up or down providing the height adjustment.

To use them, you will need a spring with a smaller height than stock. The weight jack assembly takes up about an inch of space. If you used the stock spring, the car will sit higher, even at full lock down. I'm using mine with 1/2 height springs. This allows me to adjust for stock height at full lock up, or slammed to the ground at full lock down (4 inch drop!). I would not recommend running the car on the street at full lock up unless you weld the weight jack to the car. The spring has to be custom made because they are not off-the-shelf drop springs for a Camaro. But at only $50-69 a spring its not that big of a deal. I would get springs from either Eibach (remember though, linear rate custom length, not off-the-shelf Camaro progressive rate springs), or Suspension Spring Specialists. I ordered mine from Ground Control, but there are ALOT of other respectable companies to get these springs from.

 

Here's the setup in the rear

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The setup in the front, like CH described:



There are more photos from the sig