Altering rear suspension geometry for increased anti squat and lower ride height.

By Steve Chin
Revised: December 31, 1998

In addition to a floor jack, car stands, hand tools, a vise, a drill, and a metal saw, you will need:

Safety glasses or goggles (wear them!)
2 - 2+ foot long 2x4s
Masking tape
Scribe
Center punch
Ruler
Metal file
Paint

Put the car in the air...

Park car on a flat, level surface and block front wheels. Place floor jack under rear differential and jack up car. Place car stands under body of car near front spring eye mounts and make sure car is at least 3" higher than tops of stands. Place one 2x4 between the body of the car and each car stand. Lower car gently onto 2x4/car stand combos. Ensure that the car is situated in a stable manner. Removing the rear wheels is optional, but it makes the job a little easier if you don't have a lift. Allow the rear axle to dangle to its full droop, but keep it lightly supported by the jack. Scribe a mark on each front spring eye bracket directly below the centers of the through bolts.

Drop the spring eyes from the body of the car...

Disconnect rear shock absorbers from axle. Disconnect stabilizer bar struts from their pivot brackets. Mark driveshaft rear U-joint and differential pinion yoke for alignment. Unbolt the retaining straps that hold the rear U-joint to the differential pinion yoke. Disconnect driveshaft from differential. Wrap masking tape around rear U-joint to prevent the cups from falling off. Unscrew the three screws that attach each of the front spring eye brackets to the body. After both brackets are unbolted, lower the rear axle assembly until the spring eye brackets are about 3 inches below the body pan of the car (this sometimes requires a little prying along with lowering of the jack). Mark the left and right brackets as such (optional - I don't do this, since I can tell them apart in the dark almost by smell).

Remove the brackets from the spring eyes...

Unbolt the through bolts that attach the front spring eye brackets to the front spring eyes. Remove the front spring eye brackets. Note the size of the front spring eyes.

Make the modification and fit...

Place a spring eye bracket in your vise. Draw a line from the mark made previously on the bottoms of the spring eye brackets through the center of the original spring eye mounting hole and up to the top of the bracket. Measure 3/4" above the center of the original spring eye mounting hole and mark the bracket; center-punch this spot. Drill a hole at this point (start a small pilot hole and increase the size of the drill to the same size as the existing through bolt hole). This will be the new location for the spring eye bolt. Turn the bracket over and perform the same procedure. Turn the bracket so that its open side faces down. Scribe a rectangle that is a little bit bigger than the spring eye centered over the bolt location. Drill out the corners of the rectangle, then cut the rectangle open with your metal saw (I cheated here and used a grinding disc to cut this "window" into the top of the bracket). File smooth any rough edges. Trial fit the spring eye bracket over the spring eye. If the window in the bracket does not pass over the spring eye and bushing without contacting the spring eye or bushing, the window needs to be enlarged. Paint this bracket and set aside to dry (optional). Perform the marking, drilling, cutting, fitting, and painting operation to the other bracket.

Reinstall the brackets on the spring eyes...

After the paint has dried, take the first bracket and place it over the spring eye to which it belongs. Align the hole in the spring eye bushing with the new (upper) hole in the spring eye bracket. Pin the bracket to the spring eye with its through bolt and tighten the bolt and nut. Torque the nut to 75 lb/ft. Repeat this operation with the second bracket.

Button it back up...

Lift the rear axle assembly back into place. Ensuring that spring eye brackets align with their mounting holes, loosely install spring eye bracket bolts through brackets into car body pan. This may involve jockeying the rear axle assembly around with the jack and a little prying. When all six bolts are in place, torque bolts to 25 lb/ft. Reattach shock absorbers to rear axle and torque lower nuts to 7 lb/ft. Reattach driveshaft rear U-joint to pinion yoke (ensuring that your alignment marks line up) and torque attaching bolts to 15 lb/ft. Reattach stabilizer bar struts to side rail pivot brackets and torque nuts to 30 lb/ft. Reinstall the rear wheels if you removed them. Lift car off of car stands, remove car stands and 2x4s, and put car on the ground. Unblock wheels and enjoy the lower ride height, better anti-squat geometry and improved rear roll center.

Disclaimer: Some of the operations and situations noted in these articles may lead to dangerous or hazardous conditions. I take no responsibility for anything you do as a result of seeing these articles. The information presented herein is intended strictly for informational and entertainment purposes only.

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