Help: 8.8 gear swap questions

[JoshT]

I am about to have two 8.8s sitting here at the house. One is a 28 spline axle in a 99 Ranger, the other is a 31 spline from a 98 Explorer. The 28 spline has 4.10 gears, and the 31 spline is 3.73 gears with LS. I am swaping the Explorer drive train into a 86 Ranger, but it's rear axle is way to wide. My plan is to install the Explorer axle in the 99 Ranger since it will fit better there, and the 99 Ranger's axle into the 86 Ranger. Now I know that a 31 spline LS has to stay with the 31 spline axle, and that I'll have to modify the spring pearches and add shock tabs to the explorer axle for the 99 Ranger. My bigggest problem so far is the gears themselves.

Can I just remove the gears from the 28 spline and install them in the 31 spline, and vice versa?

If so what all do I have to swap, just the ring gear or the ring gear and pinion, what?

In case you can't tell I'm still pretty clueless about the internals of a differential. I know that there are gears in there and that they turn the axles and that's about it.

 

[4.0B2]

swap out both ring gear and pinion. spline count don't matter on the r&p

but i think the ring gears on both have 41 teeth.
4.10= 41 r and 10 p
3.73= 41 r and 11 p i think
idk what happens. idk if they would interchange or not. i could be way off here.. idk. someone smarter- answer this! lol

but to get to the pinion the ring gear is in the way, so... swap out both to be safe

 

[JoshT]

but to get to the pinion the ring gear is in the way, so... swap out both to be safe

If I could swap them I was going to swap both anyway. The R&P have already worn together so I figured it'd be best to keep them as a pair.

Biggest thing is I wasn't sure if they could be swapped. I thought I had read they could before, but couldn't find it again. The other issue I had was if anything else needed to be swapped, or if it was just those two parts.

Looks like I have my work cut out for me. Never done a gear swap before, and having to relocate the spring perches and add on shock tabs. I may just stick that explorer axle under the 86 to see just how much to wide it is before tackling all that work. Pretty sure it will be way to wide, at least I know that the gear swap can be done if that is the case.

 

[4x4junkie]

The gears can be swapped, but it's a lot of work requiring numerous special tools (the pinion depth and gear backlash has to be maintained exactly how it was before). The gears cannot be mixed up either (not even from two sets of the same ratio), the ring and pinion are a matched pair.

Do you have a dial gauge w/magnetic base, dial caliper (or micrometer), bearing separator, bearing installer (or a set of various punches) and a shop press? You'll also need gear marking compound to make sure the contact pattern is acceptable afterward, and possibly a set of shims as well (and lots of patience too, as it often won't be correct on your first try).
If not, it's probably best to have a shop do the work (or maybe you can exchange the axles at a salvage yard that's willing).