What if no pinion bearing preload was recorded before disassembly of rear diff pinion seal

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

around .005" -.010" measured at the crown wheel tooth
if you have back lash at the pinion yoke , that is not the backlash you need to measure as it is a combination of axle spline and side gear clearance in the diff
what is most important is the mesh position of the crown wheel and pinion teeth, preload on the pinion bearings and diff carrier bearings
you will need a workshop manual to get the correct mesh setting and preload readings

A howling noise from a diff is an indication of the gear mesh( pinion to crown wheel) is not correct. Several reasons being worn pinion bearings--loss of preload on the pinion bearings --- crown wheel carrier bearings failing ---not sufficient preload on the bearings---wear on the teeth from incorrect diff oil in use. or simply wrong diff oil. The grade should be 80w90 OEP for normal or special oil for limited slip diffs.

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.

here is a diagram on how to get the front pinion seal out and it does mention how to get the axle loose. please do not forget to rate and comment about your experience with fixya today.

1. Before servicing the vehicle, please familiarize yourself with safety procedures.
   
2. Remove both half shafts.
   
3. Mark propeller shaft and pinion flange for installation reference.
   
4. Remove front propeller shaft.
   
5. Rotate pinion gear three to four times, to verify pinion rotates smoothly.
   
6. Record pinion flange rotating torque with an inch pound torque wrench for installation reference.
   
7. Hold flange with Holder 6719 and four bolts and washers.
   
8. Remove pinion nut.
   
9. Remove flange with Remover C-452.
   
10. Remove pinion seal with a pry tool.
    Removing the companion flange
    Measuring pinion rotating torque
    Pinion seal installer
    Tightening the pinion nut
    

To install:

1. Apply a light coating of gear lubricant on the lip of pinion seal.
   
2. Install seal with Installer C-3972-A and Handle C-4171.
   
3. Install pinion flange onto the pinion with Installer C-3718 and holder.
   
4. Hold pinion flange with Holder 6719A.
   
5. Install new pinion nut and tighten nut until there is zero bearing end-play.
   
   CAUTION Do not exceed the minimum tightening torque when installing the companion flange at this point. Damage to the collapsible spacer or bearings may result.
   
6. Tighten pinion nut to 271 Nm (200 ft. lbs.).
   
   CAUTION Never loosen pinion nut to decrease pinion bearing rotating torque and never exceed specified preload torque. If preload torque or rotating torque is exceeded a new collapsible spacer must be installed.
   
7. Record pinion flange rotating torque, with a torque wrench. Rotating torque should be equal to the reading recorded during removal plus an additional 0.56 Nm (5 inch lbs.).
   
8. If rotating torque is low, tighten pinion nut in 6.8 Nm (5 ft. lbs.) increments until rotating torque is achieved.
   
   CAUTION If maximum tightening torque is reached prior to reaching the required rotating torque, the collapsible spacer may have been damaged. Replace the collapsible spacer.
   
9. Install propeller shaft with reference marks aligned.
   
10. Install half shafts.
    

just yank it up tight with a bar about 50cms long,their should be collapsable spacer between the taper bearings just tighten it like a professional without overtightening it so and shearing something .handfull of grease in the diff casing to slow/stop any oil leaks top up with ep 90 and away you go,the crownwheel to pinion setting is just a little wiggle woggle ,or you could use a dial gauge but its quicker and easier ,too tight and it whines and too much play and it clunks,nice little wiggle woggle and it will work fine .trust me