Ford Mustang 1994-1998 Repair Guide

Pinion Seal



See Figures 1 and 2

  1. Raise and support the vehicle safely using jackstands.
  3. Matchmark the rear driveshaft yoke and the companion flange so they may be reassembled in the same orientation to maintain balance.
  5. Disconnect the driveshaft from the rear axle companion flange, then remove the driveshaft from the extension housing. Plug or cover the extension housing to prevent leakage. A plastic bag and a few rubber bands work well to cover the housing.
  7. Install an inch pound torque wrench on the pinion nut and record the torque required to maintain rotation of the pinion through several revolutions.
  9. While holding the companion flange with holder tool No. T78P-4851-A, or equivalent, remove the pinion nut.
  11. Clean the area around the oil seal and place a pan under the seal.
  13. Mark the companion flange in relation to the pinion shaft so the flange can be installed in the same position.
  15. Remove the rear axle companion flange using tool No. T65L-4851-B, or equivalent.
  17. Pry the seal out of the housing with a prytool.

To install:
  1. Clean the oil seal seat surface and install the seal in the carrier using seal replacer tool T79P-4676-A, or equivalent. Apply lubricant to the lips of the seal.
  3. Apply a small amount of lubricant to the companion flange splines, then align the marks on the flange and pinion shaft and install the flange.

Click image to see an enlarged view

Fig. Fig. 1: A new pinion shaft seal should be installed using a suitable driver

Click image to see an enlarged view

Fig. Fig. 2: A holding fixture tool is necessary when loosening or tightening the pinion shaft nut

  1. Install a new nut on the pinion shaft and apply lubricant on the washer side of the nut.
  3. Hold the flange with the holder tool while tightening the nut. Rotate the pinion to ensure proper seating and take frequent pinion bearing torque preload readings until the original recorded reading (before disassembly) is obtained.
  5. If the original recorded preload is less than the minimum specification of 170 ft. lbs. (230 Nm) for the 7.5 in diameter ring gear axle, or 140 ft. lbs. (190 Nm) for the 8.8 in. diameter ring gear axle, tighten the nut to specification. If the preload is higher than specification, tighten to the original reading as recorded.

Under no circumstance should the pinion nut be backed off to reduce preload. If reduced preload is required, a new collapsible pinion spacer and pinion nut should be installed.

  1. Remove the plug or cover from the transmission extension housing and install the front end of the driveshaft on the transmission output shaft.
  3. Connect the rear end of the driveshaft to the axle companion flange, aligning the scribed marks. Tighten the four bolts to 71-95 ft. lbs. (95-130 Nm).

Remember that when you check fluid in the rear axle, the car MUST be level. If it is necessary to raise and support the vehicle for access, then it must be supported at all four corners.

  1. Add rear axle lubricant to the carrier. Install the filler plug and tighten to 15-30 ft. lbs. (20-41 Nm).
  3. Make sure the axle vent is not plugged with debris.
  5. Remove the jackstands and carefully lower the vehicle.