5.0wned said:
Im not really convinced its anything needs to be broke in when getting gears, more just taking it easy for a few hundred miles would most likely point out any problems its having. Better to be safe then sorry, and besides taking it easy on her for a few hundred with gas prices the way they are cant be too bad haha.
While I understand where your getting at, any knowledgeable mechanic will know exactly how to set the gears up as good as they are from the factory. The only concern that could possibly arise would be defects in the new gears, which the mechanic should be able to see prior to installation. In the event that there is a defect that is not noticeable to the eye, within the first 10ish miles or so, it should become obvious. Note, the key word here is "should." There is still a chance that the issue wont show until awhile later. So "taking it easy" is not necessary. If there is a problem, then it WILL show up. Personally, I would rather know of the issue sooner than later to prevent damage to other components. If you are not a mechanic, or have ever put gears in a car, then I would suggest doing as much research as possible, and if need be, as much as you may not want to, pay someone else to install them. To get the pattern, use Zinc Oxide (available at most auto parts stores) and coat your ring gear with it. Then turn your pinion gear until it makes a complete pass around the ring gear. Next compare your pattern with the pics below.
Acceptable Patterns
Pinion is too Shallow (typically fixed by adding pinion shims, or using a different thickness)
Pinion is too Deep (typically fixed by removing pinion shims, or using a different thickness)
Additional Info on the Ford 8.8
Pinion Bering Preload New (Inch Pounds): 14-19
Pinion Bering Preload Used (Inch Pounds): 6-8
Backlash (.001 inch): 11-16
Ring Gear Bolt Torque (Foot Pounds): 60
Bearing Cap Torque (Foot Pounds): 60