Rear diff pinion seal replacement, preload torque

get the workshop manual or go see a diff repair shop
depending on the make of diff
some pinions are measured by a preload as the bearing spacer collapses to a set distance to give that preload
others have a solid spacer to get the setting
with the side bearings it is a preload measured at the crown wheel
everything is explained in the workshop manual

The only way you can get an accurate preload reading is with an in/lb torque wrench on the pinion nut with the carrier removed.

Not knowing which differential is in the truck, I'm guessing a 9.25" rear loader type.

The correct way to do it is remove the axles and ring gear carrier. Set your preload with a NEW crush sleeve and in/lb torque wrench. Re-install the ring gear carrier and check contact pattern and backlash.

That said, you probably will be alright if you re-torque the pinion nut to spec plus a hair. Look it up in a manual. EXAMPLE: if it's 210 MINIMUM ft/lb add 5-10 lbs. Preload is 10-20 in/lbs. I have seen shops do this to save the customer money (or charge them for complete disassembly and not do the work). It should take up the slack from the crush sleeve.

This is NOT the correct way, but if you are in a bind it might work. I can't guarantee the bearing won't fail in the future.

the rear axle front pinion DANA 44 or AMC?
the answer is not simple , why not read the FSM and unstand it all.
experpted....

1. On 1990-98 models, set bearing preload as follows:
   1. The required pinion gear bearing preload torque is 1/2 ft. lbs. over the noted release torque as measured above.
   2. Rotate the pinion gear three or four times with a torque wrench attached to the yoke nut. Measure the amount of torque necessary to rotate the pinion.
   3. Using a holding tool, tighten the yoke nut in small increments and remeasure until the specified torque is obtained.

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see diff chapters. its non trivial.

It depends if you are replacing the pinion seal or fitting up a whole new pinion collapsible spacer. If it just the seal that you are replacing then the tension will be to do the nut up until it is firm. Any over tightening of the nut will further collapse the spacer and over preload the bearings . If you use a new spacer then the tension on the nut is determined by a turning torque on the pinion flange as measured by a spring balance and string. To get it right consult a workshop manual.

There are two places it can leak from. The rear differential cover or the pinion seal at the front of the differential. Both are easy to replace. The pinion seal will require a little more labor than the differential cover plate. You will have to remove the drive line and then break the pinion nut loose. Use a good impact wrench for this and a six point socket for that step. Then you will need to remove the yoke from the pinion gear. Should be able to tap it off. If not use a puller. Remove the old pinion seal with a flat tip screw driver by driving it through the lip of the old seal and push the screwdriver to the side and it will pop out. Clean the hole for the new seal. install the new seal and the yoke. Tighten the pinion nut. You will need to get access to a manual to check the bearing preload on the pinion nut. Then use a torque wrench to check for correct bearing preload. Re-install the drive line.

Hi, there is no real torque spec., as the pinion gets tightened against a crush collar, creating a preload for the pinion, as the preload is tightened to 20-25 lbin, on a rotational measurement, the nut torques itself. This measurement can only be measured with the ring gear, and center section out of the housing. This may sound confusing, but this is how a typical setup would work. If you are replacing the seal, because of a leak, you could remove the flange, replace the seal reinstall the flange, snug it up, untill it is seated, then give it a small amount of tightening. You should not over tighten this nut, as it could result in pinion bearing damage. If you use caution, you can do this without an issue, Good luck...Coop

Did you get to correctly tighten the pinion nut to the proper ft pounds of torque level? This nut sets the preload on the pinion bearings, and if this value is not correct, things can go bad quickly.

Were you also able to replace the crush sleeve?

If not, this may also be the issue.

PINION FLANGE & OIL SEAL

CAUTION: Following procedure must be used to retain proper pinion bearing preload. Failure to follow procedure may result in premature axle assembly or component failure. Ensure pinion bearing preload is checked before disassembly, as previous pinion bearing preload will be used during reassembly.

Removal

1. Raise and support vehicle. Scribe reference mark on drive shaft-to-pinion flange on differential for reassembly reference. Remove bolts and "U" joint straps at pinion flange on differential.
Disconnect drive shaft from differential.
2. Remove rear wheels and brake drums to prevent any drag that may affect pinion bearing preload reading. Using INCH-lb. torque wrench, measure amount of force required to rotate pinion. This is pinion bearing preload. Record pinion bearing preload for reassembly reference.
3. Using Holder (6719), hold pinion flange. Remove pinion nut and washer. Scribe reference mark on pinion flange-to-pinion for reassembly reference. Using appropriate puller, remove pinion flange from pinion. Remove oil seal from axle housing.

Installation

1. Ensure oil seal surface in axle housing is clean. Coat lip of oil seal with gear lube. Install oil seal using appropriate seal installer. Drive oil seal into axle housing until oil seal installer contacts axle housing.
2. Install pinion flange on pinion with reference mark aligned. Using appropriate pinion flange installer, install pinion flange on pinion.

CAUTION: Washer must be installed on pinion with convex side of washer facing outward (away from pinion).

3. Install washer on pinion with convex side of washer facing outward (away from pinion). Install NEW pinion nut. Tighten pinion nut to 210 ft. lbs. (285 N.m). Rotate pinion several times to seat pinion bearings.

CAUTION: DO NOT overtighten or loosen then retighten pinion nut when adjusting pinion bearing preload. If pinion nut is overtightened, collapsible spacer on pinion must be replaced.

4. Rotate pinion using INCH-lb. torque wrench. Rotating torque should be equal to reading recorded in removal step 2) , plus 5 INCH lbs. (.056 N.m). If rotating torque is low, tighten pinion nut in small increments until proper rotating torque is obtained.
5. To install remaining components, reverse removal procedure using NEW "U" joint straps and bolts. Ensure all reference marks are aligned. Tighten bolts to specification. Check lubricant level and add if necessary.

this is for 2003 7.5 inch ring gear axle. SECTION 205-02A: Rear Drive Axle/Differential — Ford 7.5-Inch Ring Gear 2003 Mustang Workshop Manual IN-VEHICLE REPAIR Drive Pinion Flange and Drive Pinion Seal Special Tool(s) 2-Jaw Puller 205-D072 (D97L-4221-A) or equivalent Holding Fixture, Drive Pinion Flange 205-126 (T78P-4851-A) Installer, Drive Pinion Flange 205-002 (TOOL-4858-E) or equivalent Removal

1. Raise and support the vehicle.

1. Remove the rear wheel and tire assemblies.

1. CAUTION: Remove the rear brake calipers to prevent drag during the drive pinion bearing preload adjustment. CAUTION: Do not allow the calipers to hang from the brake hoses. Remove the rear brake caliper and support bracket from the knuckle as an assembly. Wire the caliper and support bracket assembly out of the way.
2. CAUTION: Index-mark the driveshaft flange and pinion flange (4851) to maintain initial balance during installation. CAUTION: The driveshaft centering socket yoke fits tightly on the pinion flange pilot. Never hammer on the driveshaft or any of its components to disconnect the yoke from the flange. Pry only in the area shown, with a suitable tool, to disconnect the yoke from the flange. Disconnect and position the driveshaft out of the way.

1. Install an Nm (inch/pound) torque wrench on the nut and record the torque necessary to maintain rotation of the drive pinion gear through several revolutions.

1. CAUTION: After removing the nut, discard it. Use a new nut for installation. Use the special tool to hold the pinion flange while removing the nut.

1. Index-mark the pinion flange and drive pinion gear stem to maintain initial balance during installation.

1. Using the special tool, remove the pinion flange.

Installation

1. Inspect the pinion flange seal journal for rust, nicks, and scratches prior to installing the flange. Polish the seal journal with fine crocus cloth, if necessary.

1. Lubricate the pinion flange splines.
   • Use SAE 80W-90 Premium Rear Axle Lubricant XY-80W90-QL or equivalent meeting Ford specification WSP-M2C197-A.

1. NOTE: Disregard the index marks if installing a new pinion flange. Position the pinion flange.

1. Using the special tools, install the pinion flange.

1. CAUTION: Do not under any circumstance loosen the nut to reduce preload. If it is necessary to reduce preload, install a new collapsible spacer (4662) and nut. CAUTION: Remove the special tool while taking preload readings with the Nm (inch/pound) torque wrench. Tighten the nut to set the preload.
   • Rotate the drive pinion occasionally to make sure the differential pinion bearings (4630) (4621) seat correctly. Take frequent differential pinion bearing torque preload readings by rotating the drive pinion with a Nm (inch/pound) torque wrench.
   • If the preload recorded prior to disassembly is lower than the specification for used bearings, then tighten the nut to specification. If the preload recorded prior to disassembly is higher than the specification for used bearings, then tighten the nut to the original reading as recorded.
   • Refer to the torque specification for used differential pinion bearings in the Specifications portion of this section.

1. CAUTION: Align the index marks. CAUTION: Install the driveshaft with new bolts. If new bolts are not available, apply Threadlock and Sealer EOAZ-19554-AA or equivalent meeting Ford specification WSK-M2G351-A5 to the threads of the original bolts. CAUTION: The driveshaft centering socket yoke fits tightly on the pinion flange pilot. To make sure that the yoke seats squarely on the flange, tighten the bolts evenly in a cross pattern as shown. Connect the driveshaft. .

1. Install the rear brake calipers.

1. Install the rear wheel and tire assemblies.

1. Lower the vehicle.

check your rear diff vent if pluged clean it out and clean up the pinion seal.sometimes if the leak is caused by pluged vent and has not been leaking long once vent is clean sometimes the leak will stop.there is not a specific torque amount because it is rotational torque(how hard to turn pinion).there is a crush sleve on the pinion and if torqued too tight or too loose brg preload will be wrong and brg damage could result.mark and remove drive shaft.remove rear wheels,brakes,axles.so when turning pinion you dont have any drag from brakes or axles.mark the position of the yoke on the pinion.remove yoke,replace seal,reinstall yoke be sure to replace pinion nut.tighten nut until it takes the exact same amount of force to turn pinion as before taking original pinion nut off.hope this helps.