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Questions and Answers

Chevy Silverado Loud Clunking In Gear

Q. Hi Vincent, Have another question regarding the 2003 Chevy Silverado SS AWD. When my truck shifts I hear a clunk from what I believe is the universal joint. I've taken it back to the dealer and they told me that there is nothing wrong. I really find that hard to believe. Maybe nothing is wrong but it sure is annoying. My son has a 2004 Chevy Silverado and his does the same thing. Has anyone else complained about this noise?

Thanks much,
Rich

Chevy Silverado Loud Clunking In Gear

A. It may be a normal noise for this truck. There may also be a service bulletin out to address it. I know they are having some problems with drive line clunk. Some repairs involve a special lube on the front drive shaft slip yoke. Others involve removing a two-piece drive shaft and installing a one-piece.

This does not mean your truck is involved, just that it may be in a certain family of possible trucks. If you are still not satisfied, call Chevrolet Customer Service, the number is in your owners manual, and let them know.

From General Motors to their Dealers:

Bulletin No.: 99-04-20-002B
Date: August 21, 2003

Subject:
Drive line Clunk

Models:
2004 and Prior Light Duty Truck Models
2003-2004 HUMMER H2

Important: The condition described in this bulletin should not be confused with Drive line Stop Clunk, described in Corporate Bulletin Number 964101R (Chevrolet 92-265-7A, GMC Truck 91-4A-77, Oldsmobile 47-71-20A, GM of Canada 934A-100) or Bump/Clunk Upon Acceleration, described in Corporate Bulletin Number 99-04-21-004A.

Some owners of light duty trucks equipped with automatic transmissions may comment that the vehicle exhibits a clunk noise when shifting between Park and Drive, Park and Reverse, or Drive and Reverse. Similarly, owners of vehicles equipped with automatic or manual transmissions may comment that the vehicle exhibits a clunk noise while driving when the accelerator is quickly depressed and then released.

Whenever there are two or more gears interacting with one another, there must be a certain amount of clearance between those gears in order for the gears to operate properly. This clearance or free play (also known as lash) can translate into a clunk noise whenever the gear is loaded and unloaded quickly, or whenever the direction of rotation is reversed. The more gears you have in a system, the more free play the total system will have.

The clunk noise that owners sometimes hear may be the result of a buildup of free play (lash) between the components in the Drive line.

For example, the potential for a Drive line clunk would be greater in a 4-wheel drive or all-wheel drive vehicle than a 2-wheel drive vehicle. This is because in addition to the free play from the rear axle gears, the universal joints, and the transmission (common to both vehicles), the 4-wheel drive transfer case gears (and their associated clearances) add additional free play to the Drive line.

In service, dealers are discouraged from attempting to repair Drive line clunk conditions for the following reasons:

  • Comments of Drive line clunk are almost never the result of one individual component with excessive lash, but rather the result of the added affect of free play (or lash) present in all of the Drive line components.

    Because all of the components in the Drive line have a certain amount of lash by design, changing Drive line components may not result in a satisfactory lash reduction.

  • While some owners may find the clunk noise objectionable, this will not adversely affect durability or performance.

Additional Information provided courtesy of AllDATA

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