For 1990-2009 cars

# Information on Proper Wheel Changing Procedures and Cautions

Subject: | Information on Proper Wheel Changing Procedures and Cautions

Models: | 2007 and Prior GM Passenger Cars and Trucks (including Saturn)

| 2007 and Prior HUMMER Models

| 2005-2007 Saab 9-7X

Attention: | Complete wheel changing instructions for each vehicle line can be found under Tire and Wheel Removal and Installation in Service Information (SI). This bulletin is intended to quickly review and reinforce simple but vital procedures to reduce the possibility of achieving low torque during wheel installation. Always refer to SI for wheel lug nut torque specifications and complete jacking instructions for safe wheel changing.

### Frequency of Wheel Changes -- Marketplace Driven

Just a few years ago, the increasing longevity of tires along with greater resistance to punctures had reduced the number of times wheels were removed to just required tire rotation intervals. Today with the booming business in accessory wheels/special application tires (such as winter tires), consumers are having tire/wheel assemblies removed -- replaced -- or installed more than ever. With this increased activity, it opens up more of a chance for error on the part of the technician. This bulletin will review a few of the common concerns and mistakes to make yourself aware of.

### Proper Servicing Starts With the Right Tools

The following tools have been made available to assist in proper wheel and tire removal and installation.

• | J 39544-KIT Complete Torque Socket Set or equivalent.

• | J 41013 Rotor Resurfacing Kit or Equivalent

• | J 42450-A Wheel Hub Resurfacing Kit or Equivalent

### Corroded Surfaces

One area of concern is corrosion on the mating surfaces of the wheel to the hub on the vehicle. Excessive corrosion, dirt, rust or debris built up on these surfaces can mimic a properly tightened wheel in the service stall. Once the vehicle is driven, the debris may loosen, grind up or be washed away from water splash. This action may result in clearance at the mating surface of the wheel and an under-torqued condition.

Caution: Before installing a wheel, remove any buildup on the wheel mounting surface and brake drum or brake disc mounting surface. Installing wheels with poor metal-to-metal contact at the mounting surfaces can cause wheel nuts to loosen. This may cause a wheel to come off when the vehicle is moving, possibly resulting in a loss of control or personal injury.

Whenever you remove the tire/wheel assemblies, you must inspect the mating surfaces. If corrosion is found, you should remove the debris with a die grinder equipped with a fine sanding pad, wire brush or cleaning disc. Just remove enough material to assure a clean, smooth mating surface.

The J 41013, or equivalent can be used to clean the following surfaces:

• | The hub mounting surface

• | The brake rotor mounting surface

• | The wheel mounting surface

Use the J 42450-A or equivalent, to clean around the base of the studs and the hub.

### Lubricants, Grease and Fluids

Some customers may use penetrating oils, grease or other lubricants on wheel studs to aid in removal or installation. Always use a suitable cleaner/solvent to remove these lubricants prior to installing the wheel and tire assemblies. Lubricants left on the wheel studs may cause improper readings of wheel nut torque. Always install wheels to clean, dry wheel studs ONLY.

Notice: Lubricants left on the wheel studs or vertical mounting surfaces between the wheel and the rotor or drum may cause the wheel to work itself loose after the vehicle is driven. Always install wheels to clean, dry wheel studs and surfaces ONLY.

### Wheel Stud and Lug Nut Damage

Always inspect the wheel studs and lug nuts for signs of damage from crossthreading or abuse. You should never have to force wheel nuts down the stud. Lug nuts that are damaged may not retain properly, yet give the impression of fully tightening. Always inspect and replace any component suspected of damage.

Tip
Always start wheel nuts by hand! Be certain that all wheel nut threads have been engaged BEFORE tightening the nut.

Important: If the vehicle has directional tread tires, verify the directional arrow on the outboard side of the tire is pointing in the direction of forward rotation.

### Wheel Nut Tightening and Torque

Improper wheel nut tightening can lead to brake pulsation and rotor damage. In order to avoid additional brake repairs, evenly tighten the wheel nuts to the proper torque specification as shown for each vehicle in SI. Use the J 39544-KIT, or the equivalent torque stick, in order to tighten the nuts with an impact wrench. When running the nuts down the studs, run the impact wrench at a reasonable speed. Always observe the proper wheel nut tightening sequence as shown below in order to avoid trapping the wheel on the wheel stud threads or clamping the wheel slightly off center resulting in vibration.

### The Most Important Service You Provide

While the above information is well known, and wheel removal so common, technicians run the risk of becoming complacent on this very important service operation. A simple distraction or time constraint that rushes the job may result in personal injury if the greatest of care is not exercised. Make it a habit to double check your work and to always side with caution when installing wheels.