CTS 2003-2005



Care Of Special Wheels

If you have invested money in magnesium, aluminum alloy or sport wheels, special precautions should be taken to make sure your investment is not wasted and that your special wheels look good for the life of the vehicle.

Special wheels are easily damaged and/or scratched. Occasionally check the rims for cracking, impact damage or air leaks. If any of these are found, replace the wheel. But in order to prevent this type of damage and the costly replacement of a special wheel, observe the following precautions:

Use extra care not to damage the wheels during removal, installation, balancing, etc. After removal of the wheels from the vehicle, place them on a mat or other protective surface. If they are to be stored for any length of time, support them on strips of wood. Never store tires and wheels upright; the tread may develop flat spots.
When driving, watch for hazards; it doesn't take much to crack a wheel.
When washing, use a mild soap or non-abrasive dish detergent (keeping in mind that detergent tends to remove wax). Avoid cleansers with abrasives or the use of hard brushes. There are many cleaners and polishes for special wheels.
If possible, remove the wheels during the winter. Salt and sand used for snow removal can severely damage the finish of a wheel.
Make certain the recommended lug nut torque is never exceeded or the wheel may crack. Never use snow chains on special wheels; severe scratching will occur.

Wheel Lug Studs/Bolts

All models use metric wheel nuts and studs. The nut will have the word ""metric" stamped on the face and the stud will have the letter ""M" into the threaded end.

The thread size of the metric wheel nuts and wheel studs are M12 X 1.5, this signifies:

M = Metric
12 = Diameter in millimeters
1.5 = Millimeters per thread

Click image to see an enlarged view

Fig. The word METRIC is stamped on the wheel retaining nuts (top arrow) and the letter M is stamped in the end of the studs (center arrow)

Removal & Installation

Never try to reuse a wheel stud once it has been removed. Whenever a wheel stud has been removed, discard it and replace it with a new one. GM specifies that only a 1.42 inch (36mm) wheel stud be used for W-Body vehicle front hub service replacement.

  1. Raise and safely support the vehicle.
  3. Remove the wheel, brake caliper, bracket and rotor. Do not allow the brake caliper to hang by the brake hose. For more information, refer to Section 9 of this manual.
  5. If using the factory recommended wheel stud removal tool or its exact equivalent, cut about 1 / 2 in. (13mm) off of the outer end of the stud to accommodate the opening of the stud remover.
  7. Position the stud at the 6 o'clock position. Use tool J 6627-A or equivalent to extract the stud from the hub. Do not hammer on the studs to remove, as this could damage the bearing.

Click image to see an enlarged view

Fig. This is one recommended tool to remove the wheel stud(s) from a front wheel drive hub

Click image to see an enlarged view

Fig. Install washers and a nut on the wheel stud, then tighten until the stud is properly seated

To install:

  1. Clean the hub and place the replacement stud in the hub.
  3. Add enough washers to draw the stud into the hub.
  5. Install the lug nut flat side to the washers and tighten until the stud head seats in the hub flange.
  7. Remove the nut and washers.
  9. Repeat for other studs as required.
  11. Install the brake parts and wheel. Tighten the lug nuts to 100 ft. lbs. (140 Nm).
  13. Lower the vehicle and recheck the wheel nut torque.

A second method to remove damaged wheel lug studs (and the one most likely to be available to most non-professionals) involves simply removing the wheel hub and bearing assembly from the vehicle and using a hydraulic press to remove the old stud and install the replacement. This task can be handled by most automotive machine shops, once the hub is off the vehicle.