Transmission Output Shaft Bearing

This procedure covers removal and replacement of the transmission output shaft bearing on a 1972 Ford F-100 with 302ci V8 and automatic transmission, requiring driveshaft removal, transmission extension housing disassembly, and bearing replacement.

Warnings

Tools required

Parts

• Transmission output shaft bearing × 1 — Use OEM specification for FMX/C4/C6 transmission
• Extension housing gasket × 1 — Use OEM specification
• Output shaft seal × 1 — Use OEM specification
• U-joint strap bolts × 4 — 3/8"-16 (if damaged)
• RTV silicone gasket maker × 1 — High-temp rated

Fluids

• Type F ATF — 3 qt

Preparation

1. Park vehicle on level ground and apply parking brake firmly
2. Place wheel chocks in front of both front wheels
3. Raise rear of vehicle using floor jack at rear axle or frame rails
4. Support vehicle on jack stands at frame rails behind transmission crossmember
5. Allow transmission to cool completely if vehicle was recently operated
6. Position drain pans under transmission extension housing area
7. Mark driveshaft and rear axle pinion yoke relationship with paint or punch marks for proper reassembly alignment

Procedure

1. 1

   Remove driveshaft
   Using appropriate sockets, remove the 4 U-joint strap bolts connecting the rear U-joint to the differential pinion yoke. Support the driveshaft to prevent it from dropping. Slide the driveshaft rearward to disengage the slip yoke from the transmission extension housing. Lower the driveshaft and remove from under vehicle. Insert a plug or wrap the extension housing opening with a shop rag to prevent fluid loss and contamination.
2. 2

   Remove speedometer cable and identify transmission type
   Locate the speedometer cable connection on the driver side of the transmission extension housing. Unscrew the speedometer cable retaining nut and carefully pull the cable and driven gear assembly from the housing. Note the transmission type (C4, C6, or FMX) as bearing specifications differ slightly. Set speedometer components aside in a clean area.
3. 3

   Support transmission
   Position a transmission jack or floor jack with wood block under the transmission oil pan. Apply slight upward pressure to support the transmission weight, but do not lift the transmission at this point. This will allow removal of the crossmember without dropping the transmission tail.
4. 4

   Remove transmission mount and crossmember
   Remove the 2 nuts or bolts securing the transmission mount to the crossmember. Remove the 4 bolts securing the crossmember to the frame rails (2 per side). Lower the crossmember and set aside. Allow the transmission to lower slightly on the jack, tilting the tail section downward to improve access to extension housing bolts.
5. 5

   Remove extension housing bolts
   Remove the bolts securing the extension housing to the transmission case (typically 4-6 depending on transmission type; verify count for your C4/C6/FMX). These are typically located around the perimeter of the housing. Note bolt length and position as some may be different lengths. On C6 transmissions, there may be additional bolts supporting a dust shield or heat shield.
6. 6

   Remove extension housing
   Carefully slide the extension housing rearward off the output shaft. It may require light tapping with a rubber mallet to break the gasket seal. Be prepared for additional transmission fluid to drain (approximately 1-2 quarts). Once clear of the output shaft, lower the housing and drain remaining fluid into drain pan. Place housing on clean work surface with opening facing up.
7. 7

   Remove output shaft seal
   Using a seal puller, pry bar, or slide hammer with seal puller attachment, remove the output shaft seal from the rear (yoke) end of the extension housing. Work carefully to avoid damaging the housing bore. Discard the old seal.
8. 8

   Inspect output shaft for wear
   Visually inspect the transmission output shaft (still in transmission case) for scoring, wear grooves, or damage in the bearing contact area and seal surface. Use a micrometer or caliper to measure shaft diameter if available. Deep grooves or significant wear indicate output shaft replacement is also needed. Minor surface imperfections can be polished with fine emery cloth.
9. 9

   Remove bearing from extension housing
   The rear support for the output shaft/slip yoke in C4/C6/FMX extension housings is typically a bushing (verify whether your transmission uses a bushing or a pressed bearing). If a bushing, it is pressed into the rear portion of the extension housing. Using a bearing puller, slide hammer with internal puller attachments, or press the bearing out from the rear of the housing working from inside toward the seal end. On some applications, the bearing can be driven out using a long punch and hammer, tapping evenly around the bearing race. Remove the bearing completely and discard.
10. 10

    Clean and inspect extension housing
    Thoroughly clean the extension housing bore using brake cleaner or parts washer solvent. Remove all old gasket material from the mounting flange using a scraper, ensuring the surface is completely clean and flat. Inspect the bearing bore for scoring, cracks, or damage. Check the bushing in the tail end (if equipped) for excessive wear. Wire brush all surfaces and dry completely with compressed air or shop rags.
11. 11

    Install new bearing
    Place the new output shaft bearing squarely at the opening of the bearing bore in the extension housing. Using a bearing driver of appropriate size (or large socket that contacts only the outer race), drive the bearing into the housing until it is fully seated against the internal shoulder. The bearing must be driven straight to avoid cocking or damaging the bearing or housing bore. Ensure bearing is fully seated by checking that it sits at the proper depth and does not protrude.
12. 12

    Install new output shaft seal
    Lightly coat the outer diameter of the new output shaft seal with Type F ATF. Position the seal squarely in the bore at the rear (output/yoke) end of the extension housing with the seal lip facing inward (toward the transmission/fluid side). Using a seal driver or appropriately sized large socket, drive the seal into the housing until it is flush with or slightly below the housing face. Do not overdrive the seal.
13. 13

    Prepare extension housing for installation
    Apply a thin coat of Type F ATF to the new bearing inner race and the seal lip. Install a new extension housing gasket onto the mounting flange of the housing. Some technicians prefer to use a thin bead of RTV silicone instead of a gasket; if using RTV, apply a 1/8-inch bead around the mounting surface and allow to set for 5 minutes before installation.
14. 14

    Reinstall extension housing
    Carefully guide the extension housing over the output shaft, aligning the housing with the transmission case. Rotate the housing slightly if needed to align the output shaft splines with the bearing. Slide the housing fully forward until it contacts the transmission case. Install all 6 extension housing bolts and tighten in a star pattern to draw the housing evenly into place. Snug bolts evenly, then torque to specification in multiple passes.
15. 15

    Reinstall crossmember and transmission mount
    Raise the transmission slightly using the jack to align the transmission mount with the crossmember position. Install the crossmember to the frame rails using the 4 bolts (2 per side). Loosely install transmission mount fasteners. Ensure transmission is properly aligned and not binding, then 48.0 lb-ft (65.0 Nm). Remove transmission jack.
16. 16

    Reinstall speedometer driven gear
    Coat the speedometer driven gear O-ring with Type F ATF. Insert the speedometer cable driven gear assembly into the extension housing, aligning the retainer tang with the notch in the housing. Thread the cable retaining nut onto the housing and tighten securely by hand, then snug with a wrench.
17. 17

    Reinstall driveshaft
    Clean the slip yoke splines and apply a thin coat of Type F ATF or multipurpose grease. Align the slip yoke with the transmission output shaft and slide forward into the extension housing until fully seated. Raise the rear of the driveshaft and align the rear U-joint with the pinion yoke using the alignment marks made during disassembly. Install the U-joint strap/U-bolt fasteners (typically 4 fasteners) and 26.0 lb-ft (35.0 Nm) in a crossing pattern to the specified torque.
18. 18

    Refill transmission fluid
    Using the transmission dipstick tube, add Type F ATF gradually to replace fluid lost during the procedure (typically 1-2 quarts), checking the dipstick frequently to avoid overfilling. Start the engine and allow to idle. Shift through all gear ranges (P-R-N-D-2-1) pausing briefly in each position, then return to Park. Check fluid level with engine running and transmission at operating temperature. Add fluid as necessary to bring level to the full mark on the dipstick.

Reassembly

1. Torque all fasteners to specification when values become available
2. Verify driveshaft alignment marks are correctly matched to prevent driveline vibration
3. Ensure no tools or parts are left under the vehicle before lowering
4. Double-check transmission fluid level after test drive when fluid is at operating temperature

Verification

• Start engine and verify no transmission fluid leaks from extension housing gasket or output shaft seal
• Check for unusual noises from transmission with engine running in Park and Neutral
• Test drive vehicle through all gears verifying smooth shifting with no abnormal vibration
• Verify no driveline vibration at highway speeds (indicates proper driveshaft alignment)
• Recheck transmission fluid level after test drive and top off if necessary
• Inspect under vehicle for any fluid leaks after test drive

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