WORKHORSE CUSTOM CHASSIS
Service Manual
2007 W Series
SECTION
7.2
PAGE
460
Automatic Transmission – Allison
2007 W Series Chassis
© 2006 Workhorse Custom Chassis — All Rights Reserved
WSM082106
but should have diffi culty in moving the race
counterclockwise, or you may be unable to move the
race at all.
Whine Noise
IMPORTANT:
Do not confuse this noise with pump whine noise, which
Do not confuse this noise with pump whine noise, which
is usually noticeable in PARK, NEUTRAL and all other
is usually noticeable in PARK, NEUTRAL and all other
gear ranges. Pump whine will vary with line pressure.
gear ranges. Pump whine will vary with line pressure.
You may notice a torque converter whine when the
vehicle is stopped and the transmission is in DRIVE or
REVERSE. This noise will increase as you increase the
engine RPM. The noise will stop when the vehicle is
moving or when you apply the torque converter clutch,
because both halves of the converter are turning at the
same speed.
Perform a stall test to make sure the noise is actually
coming from the converter.
1. Bring the vehicle to a complete stop using the service
brake.
2. Ensure that the engine is at low idle RPM.
3. Put the transmission in P, PARK.
4. Engage the P, PARK, range by slowly releasing the
service brake.
5. Apply the emergency brake and/or parking brake, if
present, and ensure it is properly engaged.
6. If the vehicle will be unoccupied with the engine
running, chock the wheels and take any other steps
necessary to keep the vehicle from moving.
7. Place your foot on the brake.
8. Place the range selector in DRIVE.
NOTICE:
You may damage the transmission if you depress the
You may damage the transmission if you depress the
accelerator for more than 6 seconds.
accelerator for more than 6 seconds.
9. Depress the accelerator to approximately 1,200
RPM for no greater than 6 seconds. Listen for torque
converter noise. A torque converter noise will increase
under this load.
Torque Converter Clutch Shudder
The key to diagnosing TCC shudder is to note when it
happens and under what conditions.
TCC shudder which is caused by the transmission,
should only occur during the apply or release of the
converter clutch. Shudder should never occur after the
TCC piston is fully applied.
If the shudder occurs while the TCC is applying, the
condition could be within the transmission or the torque
converter. Something is causing one of the following
conditions to occur:
• Something is not allowing the clutch to become fully
engaged.
• Something is not allowing the clutch to release.
•
The clutch is releasing and applying at the same time.
One of the following may be causing the conditions to
occur:
• Leaking turbine shaft seal rings
•
A restricted release orifi ce
• Defective friction material on the TCC piston
