Missing You
Have you ever built a unit that went out
running absolutely fantastic but came back with a problem only
a month or two later? Maybe you were so good to that
transmission that it was missing you and wanted to come back
for a visit!
So it went for Trent at Acadiana
Transmissions in Louisiana with a 5R110W that needed forward
planets, a common failure this unit has. It left the shop after
the repairs working like new, only to come back a little over a
month later with a problem it never had before. The
most-obvious problem was a loss of reverse, but in forward it
felt as if it had 4th and then lost 4th. It seemed to have
shifted three times but then it shifted only twice. Here is why
it was hard to tell.
This unit is actually a six-speed
transmission but uses only five gears at any given time. When
it is cold (5° F or below) the unit will shift 1-2-3-4-6.
When it warms up it shifts 1-2-3-5-6. If you look at the
application chart in Figure 1 you will see that the direct
clutches are used in reverse, fifth and sixth. If these
clutches cannot apply, you can see now why a loss of reverse is
obvious but forward may be a bit more difficult to describe.
You also may have noticed that fourth gear has a slightly
higher ratio than fifth but not enough that you can feel it by
the seat of your pants. Overdrive is sixth gear, which when the
unit is working correctly is used in both the cold and hot
shift modes.
What happened to Trent is that the sleeve
on the center support walked, as you can see in figures 2 and
3, causing a loss of direct-clutch apply oil. So why did the
sleeve walk? That’s easy – Mr. 5R110W missed Trent.
He wanted to come back for another visit! So Trent gave him an
upgrade by replacing the center support with a new one, and he
is still out roaming the streets to this day. 
©2006 Transmission Digest