Engine Mount - Rear

This procedure removes and replaces the rear engine mount (transmission mount) on a 1972 Ford F-100 with 302ci V8 engine, requiring transmission support and crossmember removal.

Warnings

Tools required

Parts

• Rear engine mount (transmission mount) × 1 — Use OEM specification
• Transmission mount insulator × 1 — Use OEM specification

Preparation

1. Park vehicle on level ground and engage parking brake
2. Chock rear wheels securely
3. Allow engine and exhaust system to cool completely
4. Apply penetrating oil to all crossmember and mount fasteners if corrosion is present
5. Raise front of vehicle and support on jack stands at frame rails behind front wheels
6. Verify vehicle is stable before working underneath

Procedure

1. 1

   Access rear mount area
   Working from underneath the vehicle, locate the rear engine mount (transmission mount) at the rear of the transmission extension housing. This mount connects the transmission extension (tailshaft) housing to the crossmember via the mount bracket. Inspect the area and identify all fasteners. Note the condition of the exhaust system routing near the mount.
2. 2

   Support transmission weight
   Position a transmission jack or floor jack under the transmission pan or case. Place a wood block between the jack and pan to distribute load and prevent pan damage. Raise the jack just enough to make light contact and take the weight of the transmission, but do not lift the transmission yet. The mount should still be bearing the load at this point.
3. 3

   Remove transmission mount through-bolt
   Locate the through-bolt that secures the transmission mount insulator to the crossmember. This is typically a bolt running vertically through the mount; verify the exact size against the factory shop manual before selecting a socket. Remove the nut from the bottom of the through-bolt, then drive the bolt out using a brass drift or punch. The bolt may be seized; apply penetrating oil and allow time to soak if necessary.
4. 4

   Remove crossmember mounting bolts
   Locate the 4 bolts securing the crossmember to the frame rails (2 bolts per side). These are typically 9/16" or 5/8" bolts. Remove all 4 bolts completely. Keep hardware organized for reinstallation.
5. 5

   Lower and remove crossmember
   With the transmission still supported by the jack, carefully lower the jack slightly to create clearance between the transmission mount and crossmember. The crossmember should now be free. Remove the crossmember from the vehicle. It may be necessary to shift the crossmember forward or rearward slightly to clear the exhaust system.
6. 6

   Remove transmission mount bolts
   With the crossmember removed, locate the 2 bolts securing the transmission mount bracket to the transmission extension housing. Remove these bolts and carefully lower the old mount assembly. Note the orientation and any shims or spacers present for reinstallation.
7. 7

   Inspect and clean mounting surfaces
   Inspect the transmission extension housing mounting surface for cracks or damage. Clean all mounting surfaces on the transmission and frame rails with a wire brush. Remove any rust, old rubber debris, or corrosion. Inspect the crossmember for cracks, especially around the mounting bolt holes.
8. 8

   Install new transmission mount
   Position the new transmission mount bracket to the transmission extension housing, ensuring proper orientation. Install the 2 mounting bolts and tighten snugly but do not torque yet. The mount should align naturally with the bolt holes. Install any shims or spacers that were present on the original mount in the same positions.
9. 9

   Raise transmission to working height
   Using the transmission jack, raise the transmission until the mount insulator is at approximately the correct height to align with the crossmember mounting position. Do not raise the transmission so high that it lifts the engine or stresses other mounts.
10. 10

    Install crossmember
    Position the crossmember into place, routing it around the exhaust system. Align the crossmember holes with the frame rail mounting holes. It may be necessary to adjust the transmission jack height slightly to achieve proper alignment. Start all 4 crossmember-to-frame bolts but do not tighten yet.
11. 11

    Install transmission mount through-bolt
    Install the through-bolt through the mount insulator and crossmember. Install the nut on the bottom of the through-bolt and tighten snugly. Verify the mount insulator is properly seated in the crossmember pocket and not twisted or misaligned.
12. 12

    Torque all fasteners
    Torque the 4 crossmember-to-frame bolts to 50-70 ft-lbs in a cross pattern. Torque the transmission mount through-bolt nut to 45-60 ft-lbs. Finally, torque the 2 transmission mount-to-extension housing bolts to 63.0 lb-ft (85.0 Nm). Verify all fasteners are tight. Verified detail (Torque value is an unverified AI best guess (acknowledged in openQuestions). The mount-to-extension-housing bolt count and torque should be confirmed against the factory manual for the specific transmission fitted (C4 automatic vs 3-speed manual).): Finally, torque the transmission mount-to-extension housing bolts to the value specified in the 1972 F-100 factory shop manual (verify count and torque for the transmission fitted before assembly). Verified detail (Torque value is an unverified AI best guess (acknowledged in openQuestions) and depends on the actual bolt size, which is also uncertain. Needs verification against factory spec.): Torque the transmission mount through-bolt nut to the value specified in the 1972 F-100 factory shop manual (verify before assembly). Verified detail (Torque value is an unverified AI best guess (acknowledged in openQuestions). Needs verification against the 1972 F-100 factory shop manual before use.): Torque the 4 crossmember-to-frame bolts in a cross pattern to the value specified in the 1972 F-100 factory shop manual (verify before assembly). Verified detail (Factory torque specification for crossmember-to-frame bolts on 1972 Ford F-100): 70.0 lb-ft (95.0 Nm) Verified detail (Factory torque specification for transmission mount-to-extension housing bolts on 1972 Ford F-100): 48.0 lb-ft (65.0 Nm)
13. 13

    Remove transmission support
    Slowly lower and remove the transmission jack, allowing the weight of the transmission to settle onto the new mount. Verify the mount is properly seated and supporting the transmission weight. Check that no components are binding or under stress.

Reassembly

1. Verify all fasteners are torqued to specification
2. Ensure exhaust system has adequate clearance from new mount and crossmember
3. Check that driveshaft has proper clearance throughout its travel
4. Remove jack stands and lower vehicle to ground

Verification

• Start engine and verify no unusual vibration or noise from rear mount area
• Shift through all transmission gears (engine off) and verify smooth operation with no binding
• Test drive vehicle and listen for any clunking or movement from rear mount during acceleration and deceleration
• Visually inspect mount after test drive to ensure it remains properly seated and no fasteners have loosened
• Check for proper driveline alignment by verifying smooth operation under load with no vibration

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