Instructions for Installation of Gearsets in Ford 8" and 9" Carriers
 

1. Mark the bearing caps to ensure re-assembly on proper side of housing. Remove the old gear set and thoroughly clean both the ring gear carrier and rear end housing with solvent. After cleaning, air dry all parts.

2. Verify that you have the correct gear ratio desired. This can be checked by dividing ring gear tooth count by the pinion tooth count. e.g. (Ring gear tooth count 37 T, pinion gear Tooth count 9 T, 37 divided by 9 = 4.11:1.

3. Check side bearing adjusters, all bolts and bearings. Replace as necessary.

4. Check ring gear back face for nicks or burrs which might prevent a flush mounting. If any are present, they may be removed by lapping gear on sand paper on a flat plate. This will give you more even and uniform pattern when setting up you new gear set. After removing ANY material, reclean the gears in solvent and redry.

5. Examine the ring gear carrier mounting surface for nicks or burrs which might prevent a flush mounting of the newly installed ring gear. Ring/Pinion tooth depth variations can result from a ring gear that is "cocked" on its mounting surface. Ring gear spacers are not recommended, but if one is used, also check it for surface imperfections. Nicks or burrs can be removed by using blackjacked grit paper or a small file.

6. A set of gears are matched, and should never be mixed with gears from other sets.

7. Assemble the pinion gear, bearings, crush collar, pinion support with new seal, and new nut. Tighten the pinion nut so the pinion rotating torque (the torque required to keep the gear and bearings rotating, with seal lubed) is 10-15 inch pounds for used bearings and 20-25 inch pounds for new bearings.  If the desired setting is exceeded, do NOT back off the nut, instead, disassemble and replace the crush collar and start again.  It is better to take your time and make adjustments in small increments and "sneak up" on the proper setting.  Rotation of the pinion nut in very small amounts can make preload settings change in large increments.  The torque required to crush the collar can be quite high, as much as 175 foot/pounds.  It will require a cheater bar to tighten the nut.

8. Backlash settings and pinion depth settings (also known as checking distance or CD) are supplied with any new gear set.  A CD of 1.100 would mean 1.100" from the face of the pinion gear nose to the centerline of the ring gear. This point should be the face where the caps mount to the housing, but should be checked to verify that it is infact the center of the bearing bore.

9. Install the pinion support into the gear carrier housing (without o-ring).  Measure the Pinion depth and determine the amount of shim required to achieve proper Checking Distance as shown in the figure.

10. Assemble the ring gear to the carrier with the proper bolts and a thread locking compound such as Locktite.  Install the ring gear carrier in the housing and install bearing caps and spanner rings, lubricating the bores to allow easier adjustment.

11. Adjustment for backlash is done by spanner rings in the housing. Backlash should be checked in several places and set at the tightest spot and is checked with a dial indicator placed tangent to the ring gear. Always be sure carrier bearings are preloaded. After setting backlash, torque bearing caps to factory specifications.

12. You are now ready to verify the tooth contact pattern. A gear marking compound should be used. Paint gear teeth with a thin coat of gear marking compound in several spots and rotate ring gear several revolutions. A tooth contact pattern will appear and should be similar to the pattern shown in illustration 'A' (note rounded ends on driven side). If the pattern is not in the approximate position shown, reset pinion depth and backlash to correct pattern. Pinion shims usually must be moved in .003 of an inch increments to notice a pattern change. If a pattern is heavy heel subtract shims, (see illustration 'B'), If a pattern is heavy toe add shims, (see illustration 'C'). The length of the pattern may vary with the amount of load applied during the check procedure.

13. Remove the pinion support, install O-ring, and re-install pinion support into housing.  Torque the support bolts to 30-40 foot/puonds.

14. Install the carrier into the differential housing and reinstall axles.  Fill the case with required amount of GL6 gear lube, and maintain the proper level at all times.

15. Break in the assembly. Drive at normal speeds for 10 miles, then stop and allow to cool for 30 minutes. Repeat this 2 to 3 times.  For towing applications, drive the vehicle for 200-300 miles before towing.