4. One or more spool valves used to direct fluid flow
5. Multidisc clutch packs or lockup bands
6. A control valve or a combination of control valves
In automatic transmissions, these systems all serve the same purposes. For this
reason, we will only discuss one type of automatic transmission in this TRAMAN. If you
want information on a specific type, use the manufacturer's maintenance and repair
manual for that unit
.
2.1.0 4L60/4L80, 4L80E, Allison
The TH400 Hydramatic transmission was a stout and versatile transmission; however, it
lacked any real fuel economy. With a three-speed gear set, it couldnot keep up with the
demands of the rising fuel prices. Along came some new additions to the transmission
world: the 4L60/4L80, 4L80E, and the Allison. These transmissions were based off the
ever popular TH400, but had a kick overdrive.
The 4L80E (
Figure 7-8
) is a truck automatic transmission that was introduced by GM in
the early 1990s. It basically uses many of the same internal components as the TH400
but has an overdrive fourth gear and uses electronics to control shift points and
firmness.
Roughly 75 percent of the 4L80Es internal parts are interchangeable with a TH400, and
the bellhousing bolt pattern and flexplate are the same as the 400, so it bolts up to big-
or small-blocks just like normal.
Figure 7-8 - 4L80E automatic transmission.
NAVEDTRA 14050A
7-9