juggernautt

I picked up a Dana 71 from a 1990 W250 for a project. I opened it up, marked my caps and pulled out the carrier. The gears are good but the bearings should be changed. As this is the furthest I've ever gone dismantling a differential, my question is, if I replace the bearings with the same brand and part # and use the same shims that were on the carrier and pinion, will the gear pattern and settings be the same or will I have to do a complete reset of the gears?

thrashingcows

You'll have to completely reset the diff, as soon as you change anything it all has to be re-done...pinion bearing and shims as well.

Angry Johnny

Personally I have found that you would need to reset the pinion bearing preload. The carrier bearing preload and backlash should be fine with just a bearing change. Now if you changed the carrier or housing then you would need to reset preload and backlash. This is if you use the same brand of bearings, but the good bearings are all pretty close.

u2slow

I changed carrier bearings just like the OP is suggesting.... and found that due to either carrier or housing wear, there was zero preload using the same shim stack. The assembly dropped right into the housing without any force. I proceeded to run the diff that way, with a Lockright, and nothing failed over the next 2 years. (in a D250 cummins truck).

It should have been re-shimmed, and pattern checked.

Re-pre-loading used pinion bearings usually ends badly. Talking up slack/play in the pinion is one thing.... put you have to ask yourself what wore away to create that slack/play?