Lowering the C5 is fast, easy, and best of all, free. Here's how to do it.
The following tools were used to make the modification.
Jack Stands (2)
Hog ring Pliers or Needle nose Pliers
Hacksaw or Serrated Knife (optional; see below)
10mm Ratcheting Wrench or 10mm Socket Wrench w/swivel extension
18mm Combination Wrench or 18mm Socket Wrench
13/16" Combination Wrench or 13/16" Deep Socket Wrench
Lowering the Rear
Make certain the car is located on a level surface.
Place blocks or boards under the front wheels to prevent the car from rolling.
Using the floor jack, raise the rear of the car, insuring that the jack is positioned in the center of the rear cross member (silver/gray in color).
Place two jack stands under the rear cross member, and SLOWLY lower the car onto them. Make sure you have raised the car high enough to allow plenty of workspace.
Locate the rear leaf spring. There is a bolt on each end (18mm bottom, 13/16" nut on top), with a rubber bushing top and bottom. At the top of the bolt, above the nut, you will see a small c-clip. This clip must be removed in order to get the nut off the top. Use hog ring pliers or needle nose pliers to remove the clip. NOTE: Only remove the bolt if you wish to lower the car more than about 1 inch in the rear. It is possible, in most cases, to lower about 1 inch without removing the bolt at all and without cutting the bushing. Cutting the bushing may make your ride a bit more harsh than before.
(SKIP IF YOU DID NOT REMOVE THE BOLT) With the c-clip removed, loosen the top nut from the bolt.
(SKIP IF YOU DID NOT REMOVE THE BOLT) Pull out the bolt and bushings from the leaf spring(the leaf spring is NOT under pressure).
(SKIP IF YOU DID NOT REMOVE THE BOLT) Cut both bushings so that the section with the extension is the only one left. Use a hacksaw or serrated knife. NOTE: If the car is too low for your personal preference, you can add back the piece or pieces you cut off.
Once the bushings are cut, reassemble the bolt, bushings, and nut through the leaf spring and A-Arm. Leave TWO threads showing on top when you re-tighten. It will seem loose, but when the car is lowered onto the ground, the weight will load the spring. Don't forget to put the c-clip back on.
Lower the car, the rear is done.
Lowering the Front
Make sure the car is in gear to prevent it from rolling.
Raise the car with the jack positioned in the center of the front cross member.
Place the two jack stands under the cross member, and slowly lower the car onto them.
Remove the front wheels. It may be necessary to slightly loosen the lug nuts before the wheels are completely off the ground.
Find the front leaf spring, and with a 10mm wrench or socket, turn the bolt as if you were loosening it (It is reverse threaded so you are actually tightening it).
Turn the bolt until there is no longer a gap between the bushing and the bolt. Measure the exposed threads to insure the other side is done the same. NOTE: On a Z51 car, the car will not drop as much as one that has the standard suspension. You can completely remove the front lowering bolt if you would like to go even lower. A spreading tool or removal of the a-arm is required to allow removal of the adjusting bolt and bushings.
Put the wheels back on and lower the car. NOTE: It may be necessary to place a board under the tires so you will be able to remove the floor jack once the car is lowered.
Yes, the procedure will work on an '01 Z06. I have an '01 Z06 and it worked. I had to cut off one section of the bushing on both front and rear bolts to get down 1". Getting the front bolts out required removing the top inner A-arm bolts and the sway bar rods.
I may raise the car 1/4" because the roads in this area are uneven and occasionally I scrape.
Lowering the front 1" causes the negative camber to get very large, so I had to adjust some out. Reducing camber caused toe out, so I had to adjust that too.
You might try lowering 3/4" to start. Hib Halverson recommends that as the maximum.