I reuploaded the pictures here:http://s412.photobucket.com/user/Project_E57/library/Ford%20Diff%20Build?sort=3&page=1I rebuilt my 8.8 late last year and figured I would make a DIY out of it. This is not the only way to go about rebuilding an IRS 8.8 but just one of the many ways to go about it. I prefer Ford OEM gears over the aftermarket offering as they have a lower tendency to whine, assuming they are setup correctly. For the rebuild parts, I use Timken bearings coupled with Ford OEM seals.
First off, I made a holder for the diff housing. This makes the rebuild much easier
First, the two pinion races and carrier bearings are pressed on. Ensure the races are completely seated down otherwise you would have issues adjusting the pinion depth. Care should be taken to ensure the races are installed straight otherwise they may damage the aluminum case.
The ring gear, pinion gear, and carrier are then prepared for assembly. A file is used to remove any burrs that may be present on machined surfaces. Running your finger on the machined surface easily picks up any burrs that may be present on these surfaces. The filling is light and minimal. Finally, the surfaces are cleaned using solvent.
Before the ring gear is bolted onto the carrier, I install the carrier onto the housing and check for the diff runout. The Ford spec here is max of 0.003". Anymore runout and the housing is not usable. My run out was just shy of 0.001" which is well within spec. The carrier is installed using shims that a 0.006" thinner than the original shims. This allows the shims to slide right in without any force.
The ring gear is then installed onto the carrier and bolts torqued to 80 - 90 foot pounds. Red loctite is required on these bolts. At this point, the carrier is ready for install. Time to prep the pinion gear.
Before the pinion bearing is pressed on, a pinion shim must be installed on the pinion. I started with the original shim that came with the housing. It is a 0.028" shim. The bearing is then pressed on. I made a press tool by welding the a pipe onto the inner race from the old pinion bearing.
At this point the pinion gear is installed into the housing and the pinion nut is torqued to give 20 inch pounds of torque. The carrier is then installed. The carrier shim thickness is selected by subtracting ~0.006" to 0.007" from both the original left and right shims. This allows the shims to slide in easily. The backlash and gear pattern are then checked. The initial setup resulted in 0.015" backlash and pattern as shown below. Ford's spec for backlash is 0.008"-0.015". While this backlash of 0.015" is within spec, the pattern is not as it favors the heel. Ideally, the pattern should be centered, heel to toe, therefore I need to move the pattern towards the toe.
On face hobbed gears such as this, in order to move the pattern toward the toe, you have to decrease the backlash. I prefer a tight backlash therefore I shot for 0.008". That means I needed to decrease the backlash by 0.007". Per Ford's documents, this would require a 0.010" change in shim thickness. I chose to go with a 0.008" shim change. This means the driver side shim was increased by 0.008" and the passenger side shim was decreased by the same amount. This worked out perfect. It resulted in 0.008" backlash and a much better pattern. The pattern is centered heel to toe as well as root to top. I'm happy with this pattern. Time to tear everything apart and establish pinion preload.
