GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Cobalt 🢒 Transmission/Transaxle 🢒 Manual Transaxle - MU3 🢒 Transmission Shifts Hard

Diagnostic Aids

An intermittent hard shift may be caused by an intermittent clutch condition.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. A static shift test is performed by shifting into all of the gear positions with the engine not operating. While performing the test one should note how the shift lever movement is felt. Also while shifting from one gear to the other feel for binding in the shift rails. You should be able to feel the detent plungers operating when coming out of a gear and going into a gear.

    2.

  2. A dynamic shift test is performed by shifting into the gear positions with the engine operating. Test for the correct mesh of the synchronizers and for the clutch releasing correctly. When shifting into and out of a gear, feel for the shift detent plungers and for the synchronizers sleeve for moving freely.

    3.

  3. The transaxle uses a DEXRON® III transaxle fluid that allows proper synchronizer operation. The incorrect fluid may cause hard shifting by varnish build-up, or not enough lubrication for proper synchronizer operation.

Step

Action

Yes

No

DEFINITION: The transaxle does not shift smoothly, or without difficulty, from one gear to the other.

1

Did you review the Symptoms - Manual Transmission and perform the necessary inspections?

Go to Step 2

Go to Symptoms - Manual Transmission

2

Inspect the clutch system for proper operation. Refer to Clutch System Description and Operation in Clutch.

Did you find or repair the condition?

Go to Step 12

Go to Step 3

3

  1. Perform a static shift test on the transaxle.
  2. Test for the following conditions:
    3. • Blockage preventing full shift lever movement
    • Excessive movement in the shift lever
    • Binding in the shift lever
    • Detent plungers or shift rails binding
    • Shift cable binding
    • Shift cable proper adjustment

Are you able to shift into all gears?

Go to Step 6

Go to Step 4

4
  1. Remove the floor console. Refer to Front Floor Console Replacement in Instrument Panel, Gages, and Console.
  2. Inspect for the following conditions:
    3. • Loose mounting
    • Foreign debris

Did you find and repair the condition?

Go to Step 12

Go to Step 5

5

Inspect for proper shift cable adjustment. Refer to Shift Cable Adjustment .

Did you find and repair the condition?

Go to Step 12

Go to Step  6

6

  1. Perform a dynamic shift test on the transaxle.
  2. Test for the following conditions:
    3. • Detent plungers or shift rails binding
    • Synchronizer sleeve binding
    • Gear clash into only one gear
    • Gear clash into all gears

Did the transaxle shift hard into all gears?

Go to Step 7

Go to Step 11

7

Inspect the transaxle for the correct fluid level and type of the transaxle fluid. Refer to Transmission Fluid Replacement .

Is the transaxle at the correct level and the proper fluid being used?

Go to Step 9

Go to Step 8

8

Drain and refill the transaxle with the correct type fluid. Refer to Transmission Fluid Replacement .

Did you find and repair the condition?

Go to Step 12

Go to Step 9

9
  1. Remove the transaxle. Refer to Transmission Replacement .
  2. Inspect the clutch pressure plate and/or clutch driven plate.

Is the clutch pressure plate and/or clutch driven plate worn or faulty?

Go to Step 10

Go to Step 11

10

Replace the clutch assembly. Refer to Clutch Pressure and Driven Plate Replacement in Clutch.

Did you find and repair the condition?

Go to Step 12

Go to Step 11

11
  1. Disassemble the transaxle. Refer to Transmission Disassemble in Manual Transmission MU3 - Unit Repair.
  2. Inspect the following components for being faulty, in the gear that is hard to shift or clashing:
    3. • Excessive synchronizers blocking ring to gear clearance
    • Synchronizer hub external splines worn or damaged
    • Excessive axial clearance in the speed gear
    • Mainshaft to speed gear bearing or journal worn
    • Shift rail and the internal shift control lever components for wear or damage
  3. Replace worn or damaged components as necessary.

Did you find and repair the condition?

Go to Step 12

Go to Diagnostic Aids

12

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 1