Dodge RAM TRUCK 1500 1995 Service Manual page 163

BR
REAR SUSPENSION AND AXLE 3 - 4 3
T R A C - L O K / P O W E R - L O K D I F F E R E N T I A L
SERVICE INFORMATION
Trac-Lok differential is available on 9 1/4 axles and
Model 60 and 80 axles. Power-Lok differential is
available on Model 70 axles. ,
In a conventional differential, torque applied to the
ring gear is transmitted to the axle shafts through
differential gears. During normal operation, the
torque transmitted to each wheel is equal at all
times. However, if one wheel spins, the opposite
wheel will generate only as much torque as the spin­
ning wheel.
In the Trac-Lok/Power-Lok differential, part of the
ring gear torque is transmitted through clutch packs.
The clutch packs contain multiple disc clutches, that
have radial grooves on the plates and concentric
grooves on the discs.
Trac-Lok differentials can also use plates and discs
with bonded fiber material that is smooth in appear­
ance.
In operation, the Trac-Lok/Power-Lok clutches are
engaged by two concurrent forces. The first being
preload force exerted through dished spring washers
contained in the clutch packs. The second from sepa­
rating forces generated by the side gears as torque is
applied through the ring gear (Fig. 1).
The Trac-Lok design provides differential action
needed for turning corners and for driving straight
ahead. However, when one wheel looses traction, the
clutch packs transfer additional torque to the wheel
having the most traction. Trac-Lok differentials resist
wheel spin on bumpy roads and provide more pulling
power when one wheel looses traction. Pulling power
is provided continuously until both wheels loose trac­
tion. If both wheels slip due to unequal traction,
Trac-Lok operation is normal. In extreme cases of dif­
ferences of traction, the wheel with the least traction
may spin.
NOISE DIAGNOSIS
If a noise occurs when turning corners, the most
probable cause is incorrect or contaminated lubri­
cant. Before removing the Trac-Lok unit for repair,
drain, flush and refill the axle with the specified lu­
bricant. Refer to Lubricant change in this Group.
A friction modifier must be added after repair ser­
vice or a lubricant change.
Vehicles with a limited slip differential should be
road tested by making 10 to 12 slow figure-eight
turns. This maneuver will pump the lubricant
through the clutch discs to eliminate a possible chat­
ter or pop noise complaint.
Refer to Group 0, Lubrication and Maintenance for
additional information.
RING
GEAR
CASE
DRIVE
PINION
PINION GEAR
MATE
SHAFT
CLUTCH
PACK
SIDE GEAR CLUTCH
PACK
J9303-15
Fig. 1 Limited Slip Differential Operation—Both
Wheels Driving
TRAC-LOK/POWER-LOK DIFFERENTIAL TEST
WARNING: WHEN SERVICING VEHICLES WITH A
LIMITED SLIP DIFFERENTIAL DO NOT USE THE EN­
GINE TO TURN THE AXLE AND WHEELS. BOTH
REAR WHEELS i i U S T BE RAISED AND THE VEHI­
CLE SUPPORTED, A LIMITED SLIP AXLE CAN EX­
ERT ENOUGH FORCE (IF ONE WHEEL IS IN
CONTACT WITH THE SURFACE) TO CAUSE THE
VEHICLE TO MOVE.
The differential can be tested without removing the
differential case by measuring rotating torque. Make
sure brakes are not dragging during this measure­
ment.
(1) Engine off, transmission in neutral, and park­
ing brake off.
(2) Place blocks in front and rear of both front
wheels.
(3) Jack up one rear wheel until it is completely off
the ground.
(4) Remove wheel and bolt Special Tool 6790 for
Trac-Lok or Special Tool for Power-Lok to studs.
(5) Use torque wrench on special tool • to rotate
wheel and read rotating torque (Fig. 2,3).