POWERTRAX Grip Pro User manual

INSTALLATION MANUAL
POWERTRAX.COM

GRIP PRO INSTALLATION MANUAL
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TABLE OF CONTENTS
Important Application Note 3
Important Lubrication Note 3
Special Notes 3
Introduction 4
Maintenance 5
Instructions 5
Warranty BACK COVER
PARTS LISTED IN THIS COMMUNICATION ARE NOT NECESSARILY MANUFACTURED BY THE ORIGINAL EQUIPMENT MANUFACTURER AND ANY REFERENCE TO
THE TRADEMARKS OR PART NUMBERS OF OTHERS ARE FOR CROSS REFERENCE INFORMATIONAL PURPOSES ONLY. ANY PHOTOGRAPH PROVIDED HEREIN IS
PROVIDED ONLY FOR ILLUSTRATIVE PURPOSES. THE ACTUAL PRODUCTS SUPPLIED MAY DIFFER. THE TRADEMARKS OF OTHERS REFERRED TO HEREIN ARE
OWNED BY THEIR RESPECTIVE COMPANIES AND ARE NOT AFFILIATED IN ANY WAY WITH MIDWEST TRUCK & AUTO PARTS, INC.®. GDP™ IS A TRADEMARK AND
WORLD AMERICAN®, MOTIVE GEAR®, MOTIVE GEAR PERFORMANCE®, EXCEL® AND EZ LINK® ARE REGISTERED TRADEMARKS OF MIDWEST TRUCK & AUTO
PARTS, INC.® USE OF THE ‘®’IN CONNECTION WITH A MARK OF MIDWEST TRUCK & AUTO PARTS, INC.® INDICATES THAT THE MARK IS REGISTERED IN AT LEAST
THE UNITED STATES. NO REPRESENTATION IS MADE WITH RESPECT TO THE SOURCE OF MANUFACTURE OF ANY PARTICULAR PART. WHILE EVERY EFFORT IS
MADE TO PROVIDE ACCURATE INFORMATION, NO GUARANTEE IS PROVIDED AS TO THE ACCURACY OF THE INFORMATION CONTAINED HEREIN. WE ARE NOT
RESPONSIBLE FOR TYPOGRAPHICAL ERRORS.

GRIP PRO INSTALLATION MANUAL
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IMPORTANT APPLICATION NOTE
Before installing the ring gear
and pressing the bearings on to the
dierential, the following two (2) items
need to be checked:
1. Ensure that your axle shaft
mates with the dierential side gear.
Some models have dierent spline
counts depending on the year of
manufacture.
2. Check the dierential ange
position (bearing shoulder to ange
face) to ensure that it is correct. You
may compare it to your old one. The
dierential ange position depends
only on the gear ratio that you are
using. This ange position may
change at certain gear ratios. Some
aftermarket ring gear and pinion sets
specify the dierential case “series”
that is required.
If you feel that you have the wrong
dierential for your application,
contact your place of purchase and
make the necessary arrangements
to exchange the dierential for the
correct one.
Once the dierential has had bearings
and/or a ring gear installed, it can
no longer be considered new and
therefore cannot be exchanged for a
new one.
IMPORTANT LUBRICANT NOTE
The Powertrax® Grip Pro™ limited-
slip dierential design uses helical
cut gears to transfer power to the
wheel with the most traction. Always
use an 80W-90 mineral/petroleum
based gear oil with at least a GL-5
rating. Synthetic oil and oils that
contain friction modiers are NOT
recommended.
SPECIAL NOTES
All Powertrax® Grip Pro™ limited slip
carriers require a certain amount of
resistance with the ground to start
to the power transfer. A Grip Pro
dierential will not transfer power if
the spinning wheel is o the ground.
In this situation a light application
of the brakes will generate enough
resistance to transfer the power to the
other wheel.
• Powertrax Grip Pro carriers can’t be
interchanged between the front and
rear dierential.
• Chrysler® 8.75” Part# GT308730
applications require the use of sealed
non-adjustable wheel bearings and
the following carrier bearings:
LM104949 Cone
LM104912 Cup
• Dana® 35 Part# GT443527
applications might require the pinion
gear to be modied to clearance the
carrier case.
• Ford® 8” Part# GT108028
applications might require the pilot
bearing area to be modied to
clearance the carrier case. GT108028
requires the use of open type ring
gear bolts part# D8OZ4216B and the
following carrier bearings:
LM102949 Cone
LM102910 Cup
• Ford® 8.8” Part# GT108831 contains
2 axle spacers. The shorter spacer is
used for 1983-’86 models & the taller
spacer is used for 1987-’14 models.

GRIP PRO INSTALLATION MANUAL
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• Ford® 9” Part# GT109028 and
GT109031 applications might
require the pilot bearing area to be
modied to clearance the carrier case.
GT109028 and GT109031 requires
the use of open style ring gear bolts
part# D8OZ4216B and the following
carrier bearings depending on size of
3rd member:
2.891” 3rd member:
LM102949 Cone
LM102910 Cup
3.0625” 3rd member:
LM603049 Cone
LM603011 Cup
• Ford® 9” Part# GT109035 and
GT109035-45 applications might
require the pilot bearing area to be
modied to clearance the carrier case.
GT109035 and GT109035-45 require
the use of open type ring gear bolts
part# D8OZ4216B and the following
carrier bearings:
3.2500” 3rd member:
LM104949 Cone
LM104911 Cup
• GM® 8.5” Part# GT201030 1988-’98
applications require the use of the
following carrier bearings:
LM102949 Cone
LM102911 Cup
INTRODUCTION
Ring and pinion backlash and
dierential carrier bearing preload are
two items of concern when installing a
dierential.
These items are typically adjusted by
means of shims or threaded adjusters.
The shims or adjusters will determine
the position of the ring gear, which
determines the backlash of the ring
and pinion set. When installing a
dierential, the backlash should be
set to the original backlash setting,
measured prior to disassembly. To
increase the backlash, adjust the
shim packs or threaded adjusters to
move the ring gear further away from
the drive pinion gear. To decrease
backlash, move the ring gear closer to
the drive pinion gear.
Bearing preload refers to the
amount of interference (press) t of
the dierential case and bearings
into the carrier housing. Adjust
the bearing preload by adding or
removing shim pack thickness or by
tightening or loosening the threaded
adjusters. Too much bearing preload
will cause premature bearing failure.
Insucient bearing preload will allow
the dierential to ‘walk’ in the housing
causing damage to the ring and pinion
set and other components.
These instructions are intended as
an aid for the experienced automobile
mechanic in properly installing the
limited-slip dierential. It is expected
that the installer be equipped with
the proper tools, equipment, and
experience before attempting the
installation.
It’s a good idea to have an extensive
selection of shims or adjustable shim
packs on hand to properly install
the dierential. Threaded adjuster
applications do not require shims.

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MAINTENANCE
It is recommended that the axle
lubricant be changed as required by
your vehicle’s service schedule.
Lubrication breakdown can lead to
accelerated wear on all rear axle
components. See IMPORTANT
LUBRICATION NOTE on page 3 for oil
and additive requirements.
INSTRUCTIONS
1. Raise and safely support vehicle.
2. Remove wheels and brake drums or
brake rotors
3. Drain lubricant from carrier and
remove cover.
4. Remove axle shafts from housing.
If your axles have “C” clips, do the
following:
A. Remove pinion shaft lock
screw and pinion shaft.
B. Push anged end of axle
shaft toward the center of the
housing and remove the “C” clip
from the button end of the axle shaft.
Repeat for other axle shaft.
C. Remove axle shafts from
housing. Be careful not to damage the
oil seals.
If your axles are non-”C” clip style, do
the following:
A. Remove axle shaft bearing
retaining plate nuts and remove the
retaining plate.
B. Use a slide-hammer to
remove the axle shafts. Be careful not
to damage the oil seals.
Note: Some axles use shims or
adjuster nuts to set the axle shaft
end play. Refer to the vehicle service
manual for the proper removal and
installation procedures for the axle
shafts.
5. For removable carriers, disconnect
the drive shaft from the pinion yoke
and remove the third member from
the axle housing.
6. Prior to further disassembly,
measure and record the ring and
pinion backlash. Mount an indicator
as shown in Figure 1. Hold the drive
pinion stationary and rotate the ring
gear in both directions to measure
the amount of backlash or free play.
Check the backlash at three to four
points around the ring gear and
record for later use.
7. Mark bearing caps “R” and “L”
to make sure that they will be
reassembled in their original position.
8. If equipped with adjuster nuts,
remove adjuster nut locks and loosen
Figure 1

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adjuster nuts.
Chrysler® tool: C-4164
Ford® tool: T70P4067-A
9. Remove bearing cap bolts and
bearing caps.
10. Remove dierential case. It may
be necessary to use a pry bar as
shown in Figure 2. Exercise caution
when prying on the carrier so that
the gasket sealing surface is not
damaged. Place shims/adjuster nuts
and bearing cups with their respective
bearing cap.
Note: Adjuster nuts will stay in the
housing in some axles.
11. Remove and discard the ring gear
bolts. With a non- metallic hammer or
brass drift punch, drive the ring gear
loose from the dierential case pilot
and remove.
12. Remove anti-lock brake tone
wheel if applicable. Consult vehicle
service manual for proper procedure.
13. Remove dierential bearing cones
from the dierential using the proper
bearing puller and adapter.
See Figure 3.
14. Clean all parts in a suitable
cleaning solvent and dry thoroughly.
Clean axle housing by pushing a
clean rag through the axle tube with
a wooden rod. Push the rag from the
end of the axle tube to the center
of the axle housing. Wipe down the
inside of the housing with a clean rag.
CAUTION: Do not spin-dry the
bearings with compressed air. Serious
damage or injury may result.
15. Remove any burrs from all
machined surfaces in the axle
housing, bearing cap and ring gear.
16. Inspect axle shaft bearing surface,
bearings and seals. Replace if
needed.
Figure 3
Figure 2

GRIP PRO INSTALLATION MANUAL
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17. Inspect dierential bearings and
replace if needed. Always replace
both the cup and cone as a set from
the same manufacturer.
18. Thoroughly clean the dierential
bearing hubs and ring gear mounting
ange prior to installation of the
bearings and ring gear.
19. Install the dierential bearing
cones onto the bearing hubs of the
dierential case using the proper
installation tool. See Figure 4.
Note: Many Dana® applications use
shims between the bearing cone
and the dierential case bearing hub
shoulder. The bearing cones must be
removed to make adjustments to the
shim pack thickness.
20. For adjuster nuts, skip to Step 23.
21. Install dierential with the bearing
cups and shims into the dierential
housing. Adjust the shim pack as
necessary to create a slip t of
the dierential into the dierential
housing. A slip t is the thickest
shim pack that can be installed by
hand with slight resistance. It will be
necessary to rotate the dierential
case after each shim thickness
change to seat the bearings.
22. Remove the dierential from the
dierential housing. Measure the
combined thickness of the shims. This
total shim thickness is what is needed
for installing the dierential (prior to
adding preload to the bearings).
23. Heat the ring gear and anti-lock
tone wheel (if applicable) with a heat
lamp or by submersing in hot water.
Do not exceed 300º F. Do not use a
torch!
24. Install anti-lock tone wheel (if
applicable) while hot onto the outside
diameter of the dierential ring gear
ange as stated in the vehicle service
manual.
25. Install the ring gear while hot onto
the dierential. Use pilot studs to align
the ring gear to the dierential as
shown in Figure 5.
Figure 4
Figure 5

GRIP PRO INSTALLATION MANUAL
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26. Using new ring gear bolts,
alternately tighten each ring gear bolt
to the proper torque:
3/8” Bolts = 50 lb ft
7/16” Bolts = 80 lb ft
1/2” Bolts = 100 lb ft
27. For adjuster nuts, skip to Step 35.
28. Select two shims of approximate-
ly equal size whose total thickness
is equal to the shim pack thickness
determined in Step 21.
29. Place the dierential assembly
with the ring gear, bearing cups and
shims into the dierential housing.
Install bearing caps and bolts in their
proper position and tighten bolts.
While tightening bearing cap bolts,
continuously rock the ring gear back
and forth to conrm backlash. If at any
time the backlash becomes reduced
to zero, remove bearing caps and ad-
just the shim packs by removing .010”
from the ring gear side and adding
.010” to the opposite side. Repeat
as needed until both bearing caps
can be torqued to the proper torque
value and ring and pinion backlash is
conrmed.
30. Rotate the dierential case several
revolutions to seat the bearings.
Check the backlash as described in
Step 6.
31. Compare the backlash reading
to the original reading taken in Step
6 and adjust as needed. To increase
backlash, remove shim thickness
from the ring gear side and add an
equal amount of shim thickness to the
opposite side. To decrease backlash,
add shim thickness to the ring gear
side and remove an equal amount
of shim thickness from the opposite
side.
Note: approximately .001” of shim
equals .001” of backlash.
32. Once the correct backlash reading
has been established, add .004” of
shim thickness to both shim packs
to preload the dierential bearings. It
will be necessary to drive the shims
into position. Do not hit the bearing
cups. It is advantageous to use a Case
Spreader to install the dierential.
33. Torque the bearing cap bolts
to the proper value and rotate the
dierential case several revolutions
to seat the bearings. Recheck the
backlash and correct if necessary.
34. Skip to Step 47.
35. Place the dierential assembly
with ring gear and bearing cups into
the dierential carrier.
36. Apply a light coat of axle oil to the
bearings and adjuster nut threads.
37. Install the bearing caps in their
original position and hand tighten the
bearing cap bolts.
38. Install the adjuster nuts (unless
still in the dierential housing) being
careful not to cross thread the
adjuster nuts causing thread damage.
39. With the adjuster nuts installed
and the bearings in position, torque

GRIP PRO INSTALLATION MANUAL
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the bearing cap bolts to the proper
torque value.
40. For Chrysler® 8-1/4” & 9-1/4”, skip
to Step 46.
41. Loosen the RH adjuster nut
(opposite the ring gear) until it is away
from the bearing cup. Tighten the LH
adjuster nut (ring gear side) until the
ring gear is slightly forced into the
drive pinion (zero backlash). Rotate
the dierential several revolutions to
ensure no binding is present. Recheck
RH adjuster nut to be sure that it is not
against the RH bearing cup. Use an
appropriate tool to turn adjuster nuts.
42. Install indicator as shown in Figure
6. Tighten RH adjuster nut until a case
spread of .008 - .012 is measured.
Rotate drive pinion several times in
each direction to seat the bearings
and to be sure that binding does not
occur. It may be necessary to readjust
the case spread by tightening the RH
adjuster nut.
43. Measure the backlash as done
in Step 6. If necessary, adjust the
backlash until it matches the original
reading taken in Step 6. Increase
backlash by loosening the LH adjuster
and tightening the RH adjuster the
same amount. Decrease backlash
by loosening the RH adjuster nut
and tightening the LH adjuster nut
the same amount. When making
adjustments, always make the nal
adjustment in the tightening direction.
For example, if the adjuster need
to be loosened one notch, loosen
it two notches and tighten it one.
When the proper backlash has been
established, install the adjuster nut
locks.
44. Install third member into axle
housing using a new gasket or silicone
sealer and tighten nuts. Reinstall drive
shaft.
45. Skip to Step 47.
46. For Chrysler® 8-1/4” and 9-1/4”
applications, using tool C-4164,
adjust the position of the dierential
until the proper backlash reading has
been established. Refer to Step 6 for
the backlash checking procedure
and original backlash reading.
Alternately tighten each adjuster nut
and rotate the dierential case several
revolutions to seat the bearings. Being
careful not to change the backlash,
repeat until each adjuster nut has
been tightened to 70 lb ft. Recheck
backlash and correct if necessary.
Install adjuster nut locks.
47. Install axle shafts into housing
being careful not to damage the oil
seals. If your axles have “C” clips, do
the following:
Figure 6

GRIP PRO INSTALLATION MANUAL
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A. Remove the snap ring
with snap ring pliers Figure 7. Then
remove the plug. See Figure 8.
Next, remove the axle spacer (where
applicable) as shown in Figure 9.
B. With the port now clear,
push anged end of axle shaft toward
the center of the housing and install
the “C” clip onto the button end of
the axle shaft. Pull axle shaft outward
so the shaft and washer seat in the
counterbore of the side gear. Repeat
for other axle shaft.
C. Install the axle spacer
(where applicable), the plug and then
the snap ring back into the side of
the carrier. Make sure snap ring is
properly seated before continuing.
If your axles are non-”C” clip style, do
the following:
1. Install axle shaft bearing
retaining plate and nuts. Tighten nuts
to proper torque.
Note: Some axles use shims or
adjuster nuts to set the axle shaft
end play. Refer to the vehicle service
manual for the proper removal and
installation procedures for the axle
shafts.
48. Using a new gasket or silicone
sealant, install axle cover and tighten
bolts.
49. Install brake drums or rotors.
50. Install wheels.
51. With the vehicle level, remove the
ll plug and ll housing to the proper
level with the lubricant described on
Page 2.
52. Lower vehicle and test operation
of axle.
Figure 7
SNAP RING

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Figure 8
Figure 9
PLUG
AXLE SPACER

GRIP PRO INSTALLATION MANUAL
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WARRANTY
POWERTRAX® warrants that all new POWERTRAX® products, will be free from defects in ma-
terial and workmanship for the rst 24 Months ( 2 YEARS ) or 100,000 miles, whichever comes
rst.
THIS WARRANTY WILL NOT APPLY IF ANY PART HAS BEEN MODIFIED, DAMAGED OR IS DE-
FECTIVE AS A RESULT OF ANY ACCIDENT, MISUSE, USE IN COMPETITIVE APPLICATIONS, IM-
PROPER INSTALLATION, NEGLIGENCE, REPAIR OR ALTERATION. COMPETITION PARTS ARE
SOLD “AS IS”, WITHOUT ANY WARRANTY WHATSOEVER. IMPLIED WARRANTIES, INCLUDING
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE EX-
CLUDED; THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF SUCH PARTS IS
WITH THE BUYER. SHOULD SUCH PARTS PROVE DEFECTIVE FOLLOWING THEIR PURCHASE,
THE BUYER AND NOT THE MANUFACTURER, DISTRIBUTOR OR RETAILER, ASSUMES THE EN-
TIRE COST OF ALL NECESSARY SERVICING OR REPAIR.
The POWERTRAX® parts warranty is voided if the part is used for competition or if it has been
modied. To make a warranty claim on parts used in non-competitive applications, distribu-
tors should contact POWERTRAX®, and individuals should contact their POWERTRAX® dis-
tributor for a Return Goods Authorization (RGA) Number. No returns will be accepted without
an RGA Number. All parts should be returned to POWERTRAX® freight prepaid. POWERTRAX®
will issue a credit equal to the original purchase price for all defective parts covered by this
warranty. In the event that a warranty claim cannot be substantiated by POWERTRAX®, the
parts will be returned to the customer freight collect.
THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUD-
ING, BUT NOT LIMITED TO, ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR
A PARTICULAR PURPOSE, AND IN NO EVENT WILL MIDWEST BE LIABLE FOR INCIDENTAL,
SPECIAL OR CONSEQUENTIAL DAMAGES INCLUDING, BUT NOT LIMITED TO, ANY LABOR
COSTS.
PART #: MANUAL-GRIPPRO
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