According to the '86 shop manual for the 8.8 diff you DO NOT have to pull anything but the companion flange and the seal. But you do have to check the preload before taking it apart and reset it when you put it back together. You need to set the preload back to the setting you measured before removing the flange or to spec, whichever is higher. If you go over the higher of these values you are stuck with having to replace the crush. If you would like me to send you a copy of the instructions, which are very specific, then let me know your e-mail address.
you can replace the pinion seal and not the crush sleeve.When you have the flange off make sure you check to see if the flange has a groove in it from the seal.Most of the time the leak is from a combination of them both.As for tightening the pinion, the proper way is remove carrier and set bearing preload, but you can tighten with a 1/2 impact. It's kinda hard to figure out how tight it needs to be until you do a few of them.
Most mechanics I know replace the pinion seal easily without replacing the crush sleeve or disassembling the rear. They do it right on the car. I have replaced the pinion seals on 4 Ford 9" rears using the following method with no problems thus far. First, remove the drive shaft. Using a sharp punch, mark the end of the pinion shaft and the pinion nut. Then carefully count the number of pinion threads that show beyond the pinion nut. Using a good impact gun, remove the pinion nut being careful not to turn the pinion shaft. Pull off the yoke noting its exact orientation so it can be replaced in exactly the same position as when removed. Pry off the old seal (a seal tool is helpful here) and replace with a new one, lubricating the seal with clean differential lube. If the yoke has a groove worn in it there are stainless sleeve kits readily available to repair the yoke. Replace the yoke in exactly the same orientation as it was removed. Replace the pinion nut and carefully tighten back to its original position with the same number of threads showing and the punch marks lined up. It is OK to tighten slightly past the mark on the pinion shaft.
The purpose of the crush sleeve is to prevent overtightening of the pinion nut which would place too much preload on the pinion bearings. The sleeve is designed to begin to crush when a specified torque is applied to the nut thus preventing excessive bearing preload. Theoretically, if you reach a specified torque or preload with the pinion nut and attempt to continue to tighten it, the sleeve is supposed to crush rather than allow further buildup in preload. It is primarily in rears set up with new gearing and bearings where bearing preload is most critical. Preload helps new bearings and gears wear in properly and preload decreases as the bearings seat themselves and wear in. Using the above method to replace the seal pretty closely returns the bearing preload to what it was before you replaced the seal. Since you haven't disturbed the gear mesh pattern between the ring and pinion there should be no increase in gear noise. I don't know any mechanics who disassemble the rear or even remove the carrier from the car just to replace the pinion seal. All I would do first is drain the gear oil to prevent a big mess on the floor. Good luck and have fun.
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