Instructions for Installing
Gears in 8.8" Solid Axle
1. Engage parking brake, put in first gear/park and chock from tires.
2. Raise rear of car, putting a jackstand in the middle of each axle tube. Placing
the front of the car on jackstands is also advised.
3. Remove rear tires – Do NOT remove drums or rotors yet.
4. Remove rear sway bar (15mm).
5. Remove driveshaft (12 point 12mm).
6. Remove differential cover and drain lube.
7. Remove differential shaft retaining bolt (5/16 – use ¼” drive with long
8. Remove differential shaft.
9. Release parking brake and remove drums or rotors; On SN-95’s, removal of
brakes will necessitate removing the calipers (13mm) and caliper brackets
10. On SN-95’s, remove ABS sensors (A female Torx socket is required).
11. Push axles in and remove c-clips from end of the axles within the differential.
12. CAREFULLY remove the axles, being sure not to damage the axle bearing
13. Remove the differential bearing caps (6 point 3/4” ½” drive socket); Bearing
caps must be reinstalled on same side of differential as they were removed.
14. Use a long prybar to dislodge the differential from axle housing. If
differential is in tightly, insert prybar through window in differential and
rotate pinion gear. The rotation of the pinion gear will push differential out
of the axle housing as the prybar contacts the axle housing. Note: Bearing
races and differential shims must be re-installed on same side of
differential as they were removed. Always keep a hand on the differential
to prevent loss of front teeth.
Removing Pinion Gear
15. Use long bar to hold pinion flange and remove the pinion nut. A piece of 3ft
by 1" U-channel with two holes drilled in it for being attached to pinion
flange works well.
16. Use puller to remove the pinion flange.
17. Remove pinion gear.
Installing Bearing and Shim on Pinion
18. Use feeler gauge to measure shim between pinion bearing and back of the
pinion gear. The pinion shims may be used in place of feeler gauges.
19. Use race to press new bearing (with shim) onto the new pinion gear.
Note: The use of the pinion depth tool is not mentioned in these instructions.
The pinion depth tool determines a reference distance between the machined
seats for the differential bearing seats and the pinion gear rear bearing seat.
Variations in the reference distance result from machining variations in the
pumpkin, not the gear sets. It has been my experience in installing FRPP
(previously Ford Motorsport) gear sets that using the same size shim on the
pinion gear provides the proper pinion depth. The machined dimensions and
tolerance of the FRPP pinion gears gear sets are essentially identical to those of
stock Ford gears. Use of non-Ford/FRPP gears may require the use of a depth
check tool as dimensions and tolerances for other brands of gear sets may be
different than Ford/FRPP gear sets.
Replacing Pinion Races and Seal
20. Use seal puller to remove pinion seal.
21. Use long steel punch to remove pinion races, if replacement is necessary.
22. Use old races or race install tool to install new races; make sure that are
installed to full depth of the bore in the differential.
23. Install new seal using large socket or seal installer.
Replacing Ring Gear
24. Remove ring rear bolts (6 point 3/4” ½” drive socket); Use long rod or long
½” drive extension through differential shaft hole to hold differential while
25. Using a brass punch or block of wood, tap ring gear off of differential.
26. Make sure the new ring gear and differential flange surfaces are free of debris
27. Position new ring rear on differential with bolt holes aligned to holes in
28. Use four bolts spaced evenly around the ring gear to draw the ring gear
against the flange; tighten each bolt in small increments to prevent the gear
from binding. If all of the four bolts cannot be started, place ring gear in hot
water for a few minutes to expand it.
29. Remove four ring gear bolts, apply Loctite to all ring gear bolts and tighten.
30. Torque bolts in alternating fashion to 70 ft-lbs.
Installing Pinion Gear
31. Install a new crush sleeve on the pinion gear, lube the bearing and install
pinion gear into the differential.
32. Place pinion flange and nut on the pinion.
33. Attach long bar to pinion flange and tighten nut just enough to remove play
in the gear.
34. Remove bar and rotate pinion gear several turns.
35. Use 1/4" drive torque wrench to check torque required to maintain rotation
of pinion gear.
36. Re-attach bar and tighten bar about 1/16 to 1/8 turn.
37. Repeat steps 34 to 46 until torque required to maintain rotation is 14 to 24 in-
lbs; 16 to 20 in-lbs is best for used bearings; 20 to 24 in-lbs is best for all new
38. Remove bar when complete.
39. Place differential in axle housing with passenger side race and shim also in
40. Install passenger side bearing cap with cast-in arrows pointing outward.
41. Snug differential cap bolts; make sure differential is not binding as bolts are
42. Install driver side race and then LIGHTLY tap shim into place with a steel
punch; make sure differential is firmly against passenger side race and shim
prior to installing driver side shim.
43. Install driver side bearing cap with arrows pointing outward.
44. Torque bolts to 70 ft-lbs.
45. Rotate differential a few turns.
46. Check backlash using dial indicator mounted to machined differential cover
surface; dial indicator should be touching outer most part of tooth with the
indicator perpendicular to tooth surface.
47. Backlash should be .008 to .012; change shims to adjust backlash, if necessary.
48. Use paint on the teeth to check pattern (primarily when using non-
Motorsport gears and/or installing a new differential).
49. Install the axles.
50. Install c-clips.
51. Install the differential shaft.
52. Install and tighten the differential shaft retaining bolt.
53. Install ABS sensor (SN-95’s).
54. Install rear brakes.
55. Install driveshaft; torque to 90 ft-lbs.
56. Replace differential cover.
57. Fill differential with lube and 4 oz. of friction modifier.
58. Install tires.
59. Lower car.
60. Make final check.
61. Lit’em up…well, first break in the gears for a few hundred miles first.