CAMPAIGN: CLUTCH FORK IMPROPERLY MACHINED
Subject: CLUTCH FORK IMPROPERLY MACHINED
Models: 1990 C5H, C6H, C7H TopKick Trucks Equipped with 427 Gas (LRO) 3116 Cat Diesel Engines (LXO), Eaton/Fuller FS4005B, FS4005C, FS5005A, FS5005C or FS5106 Transmissions (RPO's MSC, MSA, MPU, MPV or MMO) and 1.5 inch Spline (RPO MWX)
TO: ALL AFFECTED DEALERS
General Motors of Canada Limited has determined that on certain 1990 TopKick Trucks equipped with certain Eaton/Fuller transmissions, the clutch fork tangs were improperly coined, resulting in a fork that binds in the throw out bearing groove when the fork tang rotates during clutch operation. This binding can eventually result in a cracked or broken release bearing carrier. There may be no noticeable deficiency in clutch operation even though this condition exists.
To correct this condition, dealers will replace the clutch fork and throw out bearing assembly.
VEHICLES INVOLVED:
Involved are certain 1990 TopKick Trucks equipped with 427 gas (LRO) or 3116 CAT diesel engines (LXO), Eaton/Fuller FS4005B, FS4005C, FS5005A, FS5005C or FS5106 transmissions (RPO's MSC, MSA, MPU, MPV or MMO) and 1.5 inch spline (RPO MWX) and built within the following VIN breakpoints:
Model Year Model From Through ---------- ----- -------- -------- 1990 GMC LJ600001 LJ608446
All affected vehicles have been identified by the VIN listing provided to involved dealers with this bulletin. Any dealer not receiving a listing was not shipped any of the affected vehicles.
DEALER CAMPAIGN RESPONSIBILITY:
Dealers are to perform this campaign on all involved vehicles at no charge to owners, regardless of kilometres traveled, age of vehicle, or ownership, from this time forward.
Whenever a vehicle subject to this campaign is taken into your new or used vehicle inventory, or it is in your dealership for service, you are to ensure the campaign correction has been made before selling or releasing the vehicle.
Owners of vehicles recently sold from your new vehicle inventory are to be contacted by the dealer, and arrangements made to make the required modification according to instructions contained in this bulletin.
CAMPAIGN PROCEDURE:
Refer to Section 4 of the Service Policies and Procedures Manual for the detailed procedure on handling Product Campaigns. Dealers are requested to complete the campaign on all transfers as soon as possible.
OWNER NOTIFICATION:
All owners of record at the time of campaign release are shown on the attached computer listing and have been notified by first class mail from General Motors. The listings provided are for campaign activity only and should not be used for any other purpose.
PARTS INFORMATION:
Parts required to complete this campaign should be ordered through regular channels, as follows:
Part Number Description Quantity/Vehicle ------------ ------------------ ----------------- 15574633 Clutch Fork Assembly 1 15556905 Release Bearing 1
PARTS AND LABOR CLAIM INFORMATION:
Credit for the campaign work performed will be paid upon receipt of a properly completed campaign claim card, RAPID terminal or DCS transmission in accordance with the following:
Repair Code Description Time Allowance ----------- ----------------- ------------- 6A R & R Transmission 1.6
Add:
Disconnect & Connect PTO .3 Diesel w/Dual Fuel Tanks .5 w/Trans. Mounted Parking Brake .6
Time allowance includes 0.1 hour for dealer administrative detail associated with this campaign. Parts credit will be based on dealer net plus 30% to cover parts handling.
SERVICE PROCEDURE:
REMOVAL AND REPLACE: (Refer to Sections 7B-Manual Transmissions and 7C-Clutch in the 1990 Medium Truck C5H, C6H and C7H Models Service Manual, X-9033)
1. Disconnect the negative battery connections. 2. Block the wheels to prevent vehicle movement.
CAUTION:
Support the engine with a suitable hoist or jack to prevent engine from tipping prior to transmission removal.
3. Place the transmission in Neutral. 4. Disconnect propeller shaft and hanger and lay aside. 5. Disconnect power take-off (PTO) and controls, if equipped. 6. Disconnect transmission mounted park brake cable, if equipped. 7. Disconnect fuel transfer bar and lines if vehicle equipped with dual fuel tanks and diesel engine. 8. Disconnect electrical connections (speed sensor, backup light/alarm switch and/or temperature switch, if equipped). 9. Disconnect the transmission shifter from stub. 10. Disconnect return spring, clutch cable and transmission mounted support bracket. 11. Install transmission jack and support transmission for removal. Fasten a safety chain over the top of the transmission and to both sides of the jack. (Since transmission fluid was not previously drained, DO NOT tip transmission.) 12. Remove clutch housing to flywheel housing bolts. 13. Remove the transmission assembly from the vehicle. 14. Remove clutch release fork and release bearing and discard. 15. Apply a light coat of high temperature grease to the main shaft drive gear bearing retainer and splined portion of the transmission main drive gear shaft
NOTE: Do not apply too much grease. Under normal operation excess grease can be thrown onto clutch facings resulting in damage to the clutch.
16. Install new clutch release fork assembly (P/N 15574633) and new release bearing (P/N 15556905).
17. Reinstall transmission assembly. Shift the transmission into high. Rotate the transmission output flange or yoke to align the transmission main drive gear shaft with the clutch disc hub. Move the transmission forward, guiding the main drive gear shaft into the clutch disc splines. Avoid springing the clutch when the transmission is being installed. DO NOT let the transmission drop or hang unsupported in the splined hub of the clutch disc.
NOTE: When installing the transmission, DO NOT allow the weight of the transmission to hang on the clutch disc hub. The clutch disc will become distorted, and adversely affecting the clutch operation.
18. Reinstall clutch housing to flywheel housing bolts.
GAS ENGINES:
Equipped with SAE Number 2 type bell housing, torque clutch housing to flywheel housing bolts to 58 N.m (43 ft. lbs.).
DIESEL ENGINE : Equipped with SAE Number 2 type bell housing, torque clutch housing to flywheel housing bolts to 55 N.m (41 ft. lbs.).
19. Remove the transmission jack. 20. Reconnect clutch cable, transmission mounted support bracket and return spring. 21. Adjust clutch pedal free-travel. Proper free travel is between 25mm and 51mm (1 to 2 inches). 22. Reinstall transmission shifter to stub and place transmission in Neutral. 23. Reconnect electrical connections. 24. Reconnect transmission mounted park brake cable (if equipped) and adjust. 25. Reconnect the PTO, if equipped. 26. Reconnect dual fuel tank cross bar and lines, if equipped. 27. Reconnect propeller shaft and hanger. 28. Unblock the wheels. 29. Reconnect negative battery connection. 30. Install "Campaign Identification Label". 31. Test drive vehicle.
INSTALLATION OF CAMPAIGN IDENTIFICATION LABEL
Clean surface of radiator upper mounting panel and apply a Campaign Identification Label. Make sure the correct campaign number is inserted on the label. This will indicate that the campaign has been completed.
Dear General Motors Customer:
General Motors of Canada became aware of a situation on certain 1990 TopKick with specific Eaton/Fuller transmissions that may eventually reduce your truck's reliability. The clutch fork tangs on your truck were improperly coined and may result in a cracked or broken clutch release bearing carrier or binding in the clutch linkage during clutch operation. Field research indicates most customers are unaware there is even any deficiency. You should also be aware that it is very unlikely this situation will cause you any unscheduled maintenance.
In the interest of maintaining your truck's reliability, we would like to correct this condition by replacing the clutch fork and release bearing assembly at no charge to you.
Please contact your GM dealer as soon as possible to arrange a service date.
This letter identifies your vehicle. Presentation of this letter to your dealer will assist their Service personnel in completing the necessary correction to your vehicle in the shortest possible time.
Further assistance, if required, may be obtained from our Customer Assistance Centre, toll free, by calling 1-800-263-3177, or if you live in Quebec, 1-800-263-7854.
We are sorry to cause you this inconvenience; however, we have taken this action in the interest of your continued satisfaction with our products.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
