Spicer Front and Rear Axle Catalog - Manual (Page 5)

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How Limited Slip Differentials Operate
A conventional differential transmits all the ring gear torque through the differential gears to the axle shafts.
Torque is at all times equal on the axle shafts, and if one wheel slips, the other wheel can only put out as
much torque as the slipping wheel.
The Spicer Limited Slip differential has the same power flow as a conventional differential, plus a more direct
flow which automatically takes effect as driving conditions demand. This more direct power flow is from the
differential case to each axle shaft through a clutch plate and disc arrangement.
Arrangement of these plates and discs is at the option of the vehicle manufacturer, so care should be taken
during disassembly to note the arrangement of these components.
The Limited Slip construction permits differential action when required for turning corners and transmits
equal torque to both wheels when driving straight ahead. However, when one wheel tries to spin due to
leaving the ground, a patch of ice, etc., the clutch packs automatically provide more torque to the wheel
which is not trying to spin.
The Limited Slip differential resists wheel spin on bumpy roads and provides more pulling power when one
wheel tries to slip. In many cases of differences in traction, pulling power will be automatically provided until
both wheels start to slip.
In diagnosis of vehicle operators' complaints, it is important to recognize two things.
1. If, with unequal traction, both wheels slip, the Limited Slip Differential has done all it can pssibly do.
2. In extreme cases of differences in traction, the wheel with the least traction may spin after the Limited
Slip has transferred as much torque as possible to the non-slipping wheel.
How To Obtain Special Service Tools
Special service tools (see service manuals) can be obtained from the following company:
Kent-Moore
OE Tool and Equipment Group
SPX Corporation
28635 Mound Road
Warren MI 48092-3499
(800) 345-2233
POWR-LOK™
2-Piece Case
4-Pinion Mate Gears
TRAC-LOK™
1-Piece Case
2-Pinion Mate Gears
All Models except Model 80 /286: The Powr-Lok
design is identified by its 2-piece case. The Trac-Lok
design is identified by its 1-piece case.
Model 80 /286 only: Both the Powr-Lok and the Trac-
Lok use 2-piece cases in the model 80 (286) axle.
The difference between the two is in the shape of the
holes for the cross shaft. The Powr-Lok case will have
cross shaft holes that are "U" shaped in one case half
and "V" shaped in the other case half. The Trac-Lok
case will have cross shaft holes that are semicircles in
both case halves.
It is also possible to replace an existing Powr-Lok unit
with a complete Trac-Lok unit. For this purpose, the
differential case assembly must be replaced.
How To Distinguish a Powr-Lok™ from a Trac-Lok™