Workshop Repair and Service Manuals GMC SIERRA
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03-07-29-004H Manual Transmission Operating Characteristics - (May 30 2012) Manual - part 2

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This isa light rattle, and once again, vehicles with dual mass flywheels will have reducednoise. If the engine is shut off while idling in neutral with the clutch engaged,the sudden stop of the engine will create a rapid change in angular acceleration thateven dual mass flywheelscannot compensate. Because of the mass of all the components, this will create a noise.This type of noise should not be heard if the clutch is released (pedal pushed tothe floor).

Backlash

Backlash noise is created when changing engine or driveline loading. This can occurwhen accelerating from a stop, coming to a stop, or applying and releasing the throttle(loading and unloading the driveline). This will vary based on vehicle type, buildvariations, driver input, vehicle loading, etc. and is created from the necessaryclearance between all of the mating gears in the transmission, axle(s) and transfercase (if equipped).

Shift Effort

Shift effort will vary among different style transmissions and synchronizer designs.Usually the more heavy duty the transmission, the higher the shift effort becauseof the increased mass of the components. Shift effort can also be higher in cold weatherbecause the fluid will be thicker. Medium duty transmissions will not shift as quicklyas a Corvette transmission. To reduce shift effort, do not attempt to rush the shift– allow thesynchronizers to work as designed. Shifting harder will only increase the chance ofrushing past the synchronizer leading to grinding while shifting.

Non-Synchronized Gears

Some light duty truck transmissions in 1st gear (creeper-gear) and reverse gears invarious transmissions, along with all gears in some medium duty transmissions, maybe non-synchronized. This means there is not a mechanism to match input and outputshaft speeds to allow for a smooth shift. This function is left up to the driver.This can be noticed if a shift into 1st or reverse is attempted while the vehicleis rolling or before theinput shaft stops rotating leading to a gear grind. The grinding can be reduced bycoming to a complete stop and pausing for a moment before shifting into the 1st orreverse gear. Some slight grinding can be expected. In medium duty non-synchronizedtransmissions, the driver must match input shaft (engine) speed to output shaft (driveshaft)speed with every shift. This can be accomplished by double clutching, or by usingother methods. If thedriver is not able to perform this function properly, there will be gear grindingwith each improperly completed shift. Driver training may be required to correct thiscondition. Clutch brakes are used in medium duty non-synchronized transmissions toallow a shift into gear at a stop. The clutch brake is used to stop the input shaftfrom spinning, allowing a shift into gear at a stop without grinding. The clutch brakeis activated by pressingthe clutch pedal all the way to the floor. When the clutch brake is used, it is possibleto have a blocked shift with the vehicle stationary. If this occurs, engage the clutchslightly to rotate the input gear to allow the shift.

Clutch Assembly Replacement Manual Clutch     Special Tools J-5824-A Clutch Alignment Tool Removal ProcedureRemove the transmission. Refer toTransmission Replacement. Remove the clutch pressure plate bolts. Note:Dowel pins are used to align the flywheel and pressure...
Rear Case Removal Automatic     Rear Case Removal Callout Component Name 1 A/Trans Rear Case Bolt-M8-x-1.25-x-30 (Qty:-12) 2 A/Trans Rear Case Assembly Note:During removal of the rear case, use care in order to retain the sun gear-–-3rd...
Automatic Transmission Fluid Fluid Pan and or Filter Replacement Automatic     Automatic Transmission Fluid, Fluid Pan and/or Filter Replacement Callout Component Name Caution:Use Dexron-VI transmission fluid only. Failure touse the proper fluid may result in transmission internaldamage....
Torque Converter End Play Inspection Automatic Torque Converter     Special ToolsJ-8001Dial Indicator SetJ-26900-13Magnetic Indicator BaseJ-35138Converter End Play CheckerJ-39195Converter End Play Check Tool Inspect the torque converter and replace if any of thefollowing conditions...
Low and Reverse Clutch Plate Inspection Automatic Transmission Unit Automatic Clutches     Important: Perform the following measurements at 3 or morelocations.Check the plates for coning on a level surface.Replace any parts not meeting specifications.Measure the thickness of each low and reverse clutch...
Backup Lamp Switch Replacement Manual     Removal Procedure Raise and suitably support the vehicle. Refer toLifting and Jacking the Vehicle.Disconnect the backup lamp switch electricalconnector-(3). Remove the backup lamp switch.Installation Procedure...