Transmission Definitions
The following definitions are provided to establish a common language
and assist the user in describing transmission assembly related conditions.
Some of these terms or conditions are used in the transmission diagnosis section
of this service manual.
Noise Conditions
| • | Gear Noise -- a whine most noticeable in the 1st and Reverse
gears that is related to vehicle speed. A gear noise condition may become
less noticeable or disappear after an upshift. |
| • | Pump Noise -- a high pitched whine increasing in intensity
with engine RPM. This condition can be noticeable in Park and Neutral with
the vehicle standing still. |
Shift Conditions
| • | Bump -- a sudden and forceful application of the clutch or
the band. |
| • | Chuggle -- a bucking or jerking condition that may be engine
related. Chuggling may be most noticeable when the torque converter clutch
is engaged, and may feel similar to the feel of towing a trailer. |
| • | Delayed -- a condition where a shift is expected but is delayed.
Some samples of this condition could be described as clutch or band engagement
that does not occur as quickly as expected during part throttle, wide open
throttle, or engine braking. Also described as LATE or EXTENDED. |
| • | Double Bump -- two sudden and forceful application of clutch
or the band. Also defined as double feel. |
| • | Early -- a condition where a shift occurs before the vehicle
has reached the proper speed and tends to labor the engine after upshift. |
| • | End Bump -- the firmer feel at the end of a shift as compared
to the feel at the start of the shift. Also defined as END FEEL or SLIP BUMP. |
| • | Firm -- a noticeable quick application of the clutch or the
band that is considered normal with a medium to heavy throttle shift. Should
not be confused with HARSH or "rough." |
| • | Flare -- a quick increase in engine RPM accompanied by momentary
torque loss. This generally occurs during a shift. Also defined as SLIPPING. |
| • | Harsh -- a more noticeable application of the clutch or the
band as compared to FIRM. This condition is considered undesirable at any
throttle position. Also referred to as "rough." |
| • | Hunting -- a repeating quick series of upshifts and downshifts
causing a noticeable change in engine RPM. An example could be described as
a 4-3-4 shift pattern. Also defined as "busyness." |
| • | Initial Feel -- the distinct firmer feel at the start of
a shift as compared to the finish of the shift. |
| • | Late -- a shift that occurs when the engine is at higher
than normal RPM for a given amount of throttle. |
| • | Shudder -- a repeating jerking sensation similar to a CHUGGLE
but more severe and rapid in nature. This condition may be most noticeable
during certain ranges of vehicle speed. May also be used to define the condition
after torque converter clutch engagement. |
| • | Slipping -- a noticeable increase in engine RPM without an
increase in vehicle speed. The slip usually occurs during or after the initial
clutch or band apply. |
| • | Soft -- slow and almost unnoticeable clutch apply with very
little shift feel. |
| • | Surge -- a repeating engine related feeling of acceleration
and deceleration that is less intense than CHUGGLE. |
| • | Tie-up -- a condition where two opposing clutches are attempting
to apply at the same time causing the engine to labor with noticeable loss
of engine RPM. |
Throttle Positions
| • | Engine Braking -- manually downshifting during zero throttle
coastdown in order to slow the vehicle. |
| • | Full Throttle Detent Downshift -- the quick application of
the accelerator pedal to the pedal's full travel in order to force a downshift. |
| • | Heavy Throttle -- approximately 3/4 of the accelerator pedal
travel (75% throttle position). |
| • | Light Throttle -- approximately 1/4 of the accelerator pedal
travel (25% throttle position). |
| • | Medium Throttle -- approximately 1/2 of the accelerator pedal
travel (50% throttle position). |
| • | Minimum Throttle -- the least amount of throttle opening
required for a downshift. |
| • | Wide Open Throttle -- full travel of the accelerator pedal
(100% throttle position). |
| • | Zero Throttle Coastdown -- the full release of the accelerator
pedal while the vehicle is in motion and in the drive range. |
