So I just got done installing 3.73's in place of the 2.73's. I set the backlash to .008" with the dial indicator by shimming it. range is what .008" to .014"? Then I ran a pattern, it's to the high side of the ring gear indicating I need to take some shims out from underneath the pinion. But the backlash is set to the right depth. I really don't care if it whines. The guys at the parts store say it will make noise but it won't break. Anybody have any real world experience with this? It takes me an hour every time to run to the store, have them pull the old bearing, and take out shims. Then another hour to reshim the diff to get the backlash right. I'm too old and frail to keep pulling this apart and reshimming!

I got the friction modifier, any suggestions what weight oil to use? I'll run it for ten minutes, let it cool 3 times and replace the oil at 500. So right now I don't want to run synthetic since it's only to break it in.

 

you might as well just throw it together and see how it drives. ive done a couple of rears, marking the gears up helps, but sometimes even if it looks wrong its right. i think its supposed to be a little more towards the rear, anyway. i would use 75-140.

 

Thanks Roy! The haynes, Alldata, parts store, etc say to use hypoid 90Weight. It's some kind of outboard drive oil. The parts store guy, who used to be a Ford tech, said to use 80-90W, so I picked some up. This is just to break it in. Do you that heavy of an oil in your rearends?