Page 20
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4LHD/4LHDX Application Manual
Powertrain Control Solutions
REV 1.1
Converter piloting is provided by a counter bore in the end of the engine crankshaft or flywheel adapter, shown in
Figure 2.1.1-2. Axial movement of the converter is contained within this “floating pilot” to ensure that thrust loads are
not transferred to the crankshaft thrust bearing. Grease should be applied to the pilot or bore to act as a lubricant and
corrosion inhibitor. Care must be taken to ensure that the converter pilot is seated properly in the engine crankshaft or
flywheel adapter bore.
During assembly to the engine, the transmission must be supported so that it is horizontal, or with the bell housing slightly
elevated. This will prevent the torque converter from slipping out of engagement with the oil pump shaft when the shipping
bracket is removed. The bellhousing face must be squarely seated against the engine face, with locating features fully
engaged, before its attaching bolts are tightened.
After the bellhousing attachment is made, check the converter pullout (Reference 2.1.3) and then move its lug surface
into contact with the flexplate (and to bring the pilot diameter into the crankshaft bore). All bolts must be hand started
to prevent cross threading. Moving the converter into place before tightening its attaching bolts ensures that both the
transmission to engine and the converter to flexplate have been properly aligned and that the converter is free to move in
the crankshaft bore without loading the crankshaft bearings. The transmission to engine attachment, and the converter to
flexplate must NOT be drawn into position with only one bolt tightened with a power gun.
The flexplate must be indexed for alignment to the converter attachment lugs. Access for indexing the flexplate ring gear
is available on some of the transmission bell housings adjacent to the starter pocket. In other cases, there is no access
provision and the flexplate is indexed via the engine crankshaft pulley.
A paint spot is applied to the front edge of the torque converter to indicate the lowest mass location as measured during
the converter balancing operation at the manufacturing plant. The spot may be used to line up with any identified heavy
spot on the flexplate during assembly to the engine.
The following figures illustrates the converter bolt patterns and thread sizes. The choice of bolt must consider factors such
as thread engagement and clearances at the bolt head and thread end. The threaded end must not bottom out against
the converter cover. A thread adhesive should be used to ensure durability.
Figure 2.1.1-2: Torque Converter Pilot Arrangement
Rev
Sheet 79
24214609
4.2.4. Flexplate to Converter Connection
Converter piloting is provided by a counterbore in the end of the engine crankshaft, shown
in Figure 4.2.4-1. Axial movement of the converter is contained within this “floating pilot” to
ensure that thrust loads are not transferred to the crankshaft thrust bearing. Grease should
be applied to the pilot or bore to act as a lubricant and corrosion inhibitor. Care must be
taken to ensure that the converter pilot is seated properly in its bore.
During assembly to the engine, the transmission must be supported so that it is
horizontal, or with the bell housing slightly elevated. This will prevent the torque
converter from slipping out of engagement with the oil pump shaft when the shipping
bracket is removed. The transmission case face must be squarely seated against the
engine face, with locating dowels fully engaged, before its attaching bolts are tightened.
After the case attachment is made, the converter must be moved to bring its lug surface
into contact with the flexplate (and to bring the pilot diameter into the crankshaft bore).
All bolts must be hand started to prevent cross threading. Moving the converter into
place before tightening its attaching bolts ensures that both the transmission to engine
and the converter to flexplate have been properly aligned and that the converter is free to
move in the crankshaft bore without loading the crankshaft bearings. The transmission to
engine attachment, and the converter to flexplate must NOT be drawn into position with
only one bolt tightened with a power gun.
The flexplate must be indexed for alignment to the converter attachment lugs. Access for
indexing the flexplate ring gear is available on some of the transmission case bell
housings adjacent to the starter pocket. In other cases, there is no access provision and
the flexplate is indexed via the engine crankshaft pulley.
A paint spot is applied to the front edge of the torque converter to indicate the lowest
mass location as measured during the converter balancing operation at the
manufacturing plant. The spot may be used to line up with any identified heavy spot on
the flexplate during assembly to the engine.
The following figures illustrates the converter bolt patterns and thread sizes. The choice
of bolt must consider factors such as thread engagement and clearances at the bolt head
and thread end. The threaded end must not bottom out against the converter cover. A
thread adhesive should be used to ensure durability.
Figure 4.2.4-1 Torque Converter Pilot Arrangement
END OF
ENGINE
CRANKSHAFT
FLEXPLATE
➤
➤
➤
TORQUE CONVERTER HUB
(CONVERTER PILOTING)
