Customer Satisfaction - Engine Flywheel/Clutch Interference

THIS BULLETIN IS BEING REVISED TO ADD NEW INSPECTION STEPS TO THE "SERVICE PROCEDURE". EFFECTIVE UPON RECEIPT OF THIS BULLETIN, THE NEW INSPECTION PROCESS MUST BE USED. THE ORIGINAL INSPECTION PROCESS LABOR OPERATION (V1465) WILL NO LONGER BE ACCEPTED AFTER THIS DATE. PLEASE DISCARD ALL COPIES OF 06523b.

***************THIS RECALL IS IN EFFECT UNTIL MARCH 31, 2007***************

Certain 2006 Chevrolet Corvette model vehicles equipped with 6.0L V8 (RPO LS2 - VIN U) or 7.0L V8 (RPO LS7 - VIN E) engine and manual transmission may have a condition in which the flywheel may have been incorrectly machined, resulting in insufficient clearance for clutch cover self adjustment, reducing clutch life.

This program will expire on March 31, 2007.

Dealers are to inspect and, if necessary, replace the engine flywheel.

Involved are certain 2006 Chevrolet Corvette model vehicles equipped with 6.0L V8 (RPO LS2 - VIN U) or 7.0L V8 (RPO LS7 - VIN E) engine and manual transmission and built within these VIN breakpoints:

Important: Dealers are to confirm vehicle eligibility prior to beginning repairs by using the GM Vehicle Inquiry System (GMVIS). Not all vehicles within the above breakpoints may be involved.

For dealers with involved vehicles, a listing with involved vehicles containing the complete vehicle identification number, customer name, and address information has been prepared and will be provided through the applicable system listed below. Dealers will not have a report available if they have no involved vehicles currently assigned.

-- US GM - GM DealerWorld Recall Information

--- Canadian GM - GMinfoNet Recall Reports

-- Export dealers - sent directly to dealers

The listing may contain customer names and addresses obtained from Motor Vehicle Registration Records. The use of such motor vehicle registration data for any purpose other than follow-up necessary to complete this program is a violation of law in several states/provinces/countries. Accordingly, you are urged to limit the use of this report to the follow-up necessary to complete this program.

Parts required to complete this program are to be obtained from General Motors Service Parts Operations (GMSPO). Normal orders should be placed on a DRO = Daily Replenishment Order. In an emergency situation, parts should be ordered on a CSO = Customer Special Order.

Important: Due to the small number of vehicles involved and due to limited initial parts availability, dealers are encouraged not to order program parts for use as shelf stock. Parts should only be ordered when inspection determines that it is necessary to replace the flywheel.

Important: The service procedure contained in this program is different from the service procedure found in the appropriate service manual. As a result, the labor time allowance has been revised to correspond with this new service procedure.

Flywheel and Clutch Assembly Inspection for 2006 Chevrolet Corvette Vehicles Equipped with a 6.0L (LS2) or 7.0L (LS7) Engine and 6-Speed Manual Transmission (MM6/MZ6)

There are six bolts that attach the clutch pressure plate cover to the flywheel. Only three of the six bolt holes on the flywheel have adjacent locating pins. The flywheel has alternating deep and shallow flywheel rim steps. Some flywheels were produced with the locating pin adjacent to the wrong step location. If the locating pins are next to the wrong bolt holes on the flywheel, the clutch cover ends up indexed improperly (off one bolt hole), which may cause interference between the flywheel and the clutch pressure plate cover. Refer to the Flywheel Inspection photographs below before performing the Flywheel Inspection procedure.

Flywheel Inspection Photographs

Flywheel Inspection

1. Raise and support the vehicle. Refer to Lifting and Supporting the Vehicle in SI.

Important: Only three of the six clutch pressure plate cover bolts (1) have the locating pin (1) next to them.




2. Position the flywheel so that one of the three clutch pressure plate cover bolts (1) with a locating pin (1) is visible in the left (driver's side) vent opening of the bell housing.




Important: Ensure meaasurement is from the non-machined rim surface of the flywheel and NOT the machined pad for the clutch pressure plate cover.

3. Measure the distance between the non-machined rim surface at the left of the machined pad of the flywheel to the edge of the bell housing vent openings. Ensure that the flywheel position is the same as shown in Step 2.

•	If the flywheel measurement is about 60.5 mm (2 3/8 in), the flywheel is indexed properly. No further action is requried.

•	If the flywheel measurement is about 50.8 mm (2 in), the flywheel is NOT indexed properly. Refer to Clutch Assembly Inspection in this bulletin.

Clutch Assembly Inspection

Important: The bell housing must be removed from the engine before you can inspect the clearance between the rivet head on the clutch pressure plate cover and the raised step on the flywheel.

1. Refer to Clutch Assembly Replacement procedure for the 6.0L (LS2) engine or 7.0L (LS7) engine in SI.
2. Perform the inspection after the bell housing has been removed from the engine. Do not remove clutch assembly before performing inspection.

1. Inspect the clearance between each rivet head on each pressure plate plug and the raised step on the flywheel. There are three locations on the clutch pressure plate to inspect.

1.1.	Rotate the flywheel while it is attached to the engine to bring each pressure plate lug rivet head into view.

1.2.	Use a feeler gauge with a stock thickness of 0.05 mm (0.002 inch) to determine if there is interference between each of the pressure plate lug rivet heads and the flywheel step.

1.3.	Slide the feeler gauge horizontally along the shallow flywheel step.





•

The clearance between each of the three pressure plate lug rivet heads (1) and flywheel step must be 6 mm (15/64 inch) or greater at all three locations. If the clearance between the pressure plate lug rivet head (1) and the flywheel step is 6 mm (15/64 inch) or greater at all three locations, the flywheel does not require replacement. Reassemble the vehicle components and proceed to step 5. Refer to Clutch Assembly procedure for the 6.0L (LS2) engine or 7.0L (LS7) engine in SI.





•

If the clearance between the pressure plate lug rivet head (1) and the flywheel step is greater than 0.05 mm (0.002 inch), but is less than 6 mm (15/64 inch) at any of the three pressure plate lug rivet head (1) and flywheel step locations, replace the flywheel only . Perform service procedure steps 2, 3 and 5. Refer to information in third bulletin point before replacing the flywheel.





•	If there is less than 0.05 mm (0.002 inch) clearance between any of the pressure plate lug rivet heads (1) and flywheel step locations, the flywheel and clutch assembly must be replaced. Perform service procedure steps 2-5.





Important: Remove the clutch pressure plate bolts in the sequence shown, starting with the number one and following in numerical order.

2. Remove the flywheel. Refer to Engine Flywheel Replacement and Engine Flywheel Removal procedures for the 6.0L (LS2) engine or 7.0L (LS7) engine in SI.

Important: During the powertrain build process, balance weights may be added to the flywheel. Install the same size balance weights onto the new flywheel in the same location as the old flywheel. Apply Threadlocker --Red, GM P/N 12345382 (Canadian P/N 10953489), or equivalent, to balance weights before pressing them into the flywheel.

3. Install new flywheel (P/N 12571611). Refer to Engine Flywheel Installation and Engine Flywheel Replacement procedures for the 6.0L (LS2) engine or 7.0L (LS7) engine in SI.

Submit a Product Claim with the information indicated below:

Refer to the General Motors WINS Claims Processing Manual for details on Product Recall Claim Submission.

General Motors will notify customers of this program on their vehicle (see copy of customer letter included with this bulletin).

Letters will be sent to known owners of record located within areas covered by the US National Traffic and Motor Vehicle Safety Act. For owners outside these areas, dealers should notify customers using the attached sample letter.

All unsold new vehicles in dealers' possession and subject to this program must be held and inspected/repaired per the service procedure of this program bulletin before customers take possession of these vehicles.

Dealers are to service all vehicles subject to this program at no charge to customers, regardless of mileage, age of vehicle, or ownership, from this time forward.

Customers who have recently purchased vehicles sold from your vehicle inventory, and for which there is no customer information indicated on the dealer listing, are to be contacted by the dealer. Arrangements are to be made to make the required correction according to the instructions contained in this bulletin. A copy of the customer letter is provided in this bulletin for your use in contacting customers. Program follow-up cards should not be used for this purpose, since the customer may not as yet have received the notification letter.

In summary, whenever a vehicle subject to this program enters your vehicle inventory, or is in your dealership for service in the future, you must take the steps necessary to be sure the program correction has been made before selling or releasing the vehicle.

Dear General Motors Customer:

This notice is sent to inform you that Chevrolet is conducting a customer satisfaction program that affects certain 2006 Chevrolet Corvette model vehicles equipped with a 6.0L or 7.0L V8 engine and 6-speed manual transmission.

We have learned that your vehicle may have been built with a condition in which the engine flywheel may interfere with the clutch and cause reduced clutch lining life.

: To prevent this condition from occurring, your Chevrolet dealer will inspect and, if necessary, replace the engine flywheel. This service will be performed for you at no charge .

To limit any possible inconvenience, we recommend that you contact your dealer as soon as possible to schedule and appointment for this repair. By scheduling an appointment, your dealer can ensure that the necessary parts will be available on your scheduled appointment date.

The enclosed customer reply form identifies your vehicle. Presentation of this form to your dealer will assist in making the necessary correction in the shortest possible time. If you no longer own this vehicle, please let us know by completing the form and mailing it back to us.

If you have any questions or need any assistance, just contact your dealer or the appropriate Customer Assistance Center at the number listed below. The Customer Assistance Center’s hours of operation are from 8:00 AM to 11:00 PM, EST, Monday through Friday.

If your vehicle is within the New Vehicle Limited Warranty your dealer may provide you with shuttle service or some other form of courtesy transportation while your vehicle is at the dealership for this repair. Please refer to your Owner’s Manual and your dealer for details on Courtesy Transportation.

We sincerely regret any inconvenience or concern that this situation may cause you. We want you to know that we will do our best, throughout your ownership experience, to ensure that your Chevrolet Corvette provides you many miles of enjoyable driving.

Scott Lawson

General Director,

Customer and Relationship Services

Enclosure

06523