GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2007 🢒 CTS 🢒 Transmission/Transaxle 🢒 Manual Transmission - Tremec 6-Speed 🢒 Transmission Shifts Hard

Diagnostic Aids

An intermittent hard shift may be caused after installation of a new clutch actuator. With a new clutch actuator, the annular seal may not be in the forward position and not allow full clutch release. With a self adjusting clutch, the clutch may be between adjustments and not allow full clutch release. This might be felt by a low clutch pedal load. After several applications, the clutch may adjust properly to give the proper pedal feel.

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 when going into a gear.

    2.

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

    3.

  3. The transmission uses a transmission fluid that allows proper synchronizer operation. The incorrect fluid may cause hard shifting from varnish build up, or from not enough lubrication for proper synchronizer operation. Only use the proper transmission fluid.

Step

Action

Yes

No

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

1

Did you review the Symptoms - Manual Transmission operations 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.

Did you find or repair the condition?

Go to Step 11

Go to Step 3

3

  1. Perform a static shift test on the transmission.
  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 linkage binding
    • Shift linkage proper adjustment

Are you able to shift into all gears?

Go to Step 7

Go to Step 4

4

Remove the shift control shift closeout boot and foam isolator. Refer to Shift Control Shift Closeout Boot Replacement.

Inspect for the following:

    • Loose mounting
    • Foreign debris
    • Interference to foam isolator

Did you find and repair the condition?

Go to Step 11

Go to Step 5

5

  1. Perform a dynamic shift test on the transmission.
  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 transmission shift hard into all gears?

Go to Step 6

Go to Step 10

6

Inspect the transmission for the correct fluid level and the correct type of transmission fluid. Refer to Transmission Fluid Replacement and Lubrication Specifications.

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

Go to Step 8

Go to Step 7

7

Drain and fill the transmission with the correct type fluid. Refer to Transmission Fluid Replacement.

Did you find and repair the condition?

Go to Step 11

Go to Step 8

8
  1. Remove the transmission. 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 9

Go to Step 10

9

Replace the clutch assembly. Refer to Clutch Assembly Replacement.

Did you find and repair the condition?

Go to Step 11

Go to Step 10

10
  1. Disassemble the transmission. Refer to Transmission Disassemble.
  2. Inspect the transmission for the following faulty components 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 10

Go to Diagnostic Aids

11

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 1