If your wondering if you should convert your "snap-in" stub axle R-180 to "bolt-in" stub axles yourself or if have a rear-end specialist do it...
I think you can easily do this yourself, the only "special" tools you'll need are a torque wrench, a big hammer, and a 3/16" pin punch. Here's how you do it.
Step by Step:
1) Drain the oil and pull the rear cover off the diff.
2) Match mark the bearing retainers (aluminum things with 5 bolts) on the sides of the diff housing so you can put them back on the correct sides and so they are indexed the same way. I make a small center punch mark on the retainer that corresponds to a similar mark on the housing on one side and the same except with two marks on the opposite side.
3) Pull the bolts that hold the retainers in.
4) Pull the retainers out *one at a time* being sure that any shims under them stay with the appropriate retainer. Make sure there are no shims stuck to the housing! I tie the shims onto the retainers with a zip-tie so there is NO WAY I can mix them up. When you pull the retainers the carrier will be loose, don't drop it! If the retainers don't want to come out by hand try this: Use a hammer and drift against one of the "ears" on the bolt flange to rotate the retainer. This usually breaks the seal and any paint loose so the retainer slides right out.
5) Pull the carrier out of the housing being careful that neither of the bearings falls off. The bearings should be a light press fit but sometimes they will slide off. If one does slide off be sure that any shims under it stay with it and zip-tie it to the corresponding retainer.
6) Clamp the carrier in a bench vise across the "flat" part of the opening with the ring gear up.
7) Match mark the ring gear and carrier so it all goes back together the same. Note that the gears are harder than your center punch so a carbide scribe works best. You can use a paint marker or felt pen but you must be VERY careful not to wipe off your match marks.
8) Flatten out the lock tabs for the ring gear bolts.
9) Pull the ring gear bolts and gently tap the ring gear down with a drift or block of wood. Work your way around if it's stubborn so it doesn't cock sideways.
10) Take the ring gear off of the carrier.
11) Match mark one spider gear and one side gear to the carrier.
12) Match mark one end of the spider pin (big pin going crossways through the carrier) near it's edge so you can re-install it with the same orientation.
13) Locate the small roll pin that retains the spider pin and tap it out with a pin punch. Don't lose it! it's the only "small" part in the diff.
14) Tap out the spider pin being careful that the bowl shaped thrust washers each stay with their respective spider gears and that the side gears don't fall out. I zip-tie the washers to the spider gears. Note: Some diffs don't have these washers.
15) Remove the side gears being careful that the thrust washers stay with their respective gears, use zip-ties so you can't mix them up. Note: Some diffs don't have these washers either.
16) On the donor side gears that had bolt-in stub axles, tap out the threaded inserts. You can do this by sitting the gear over the opening of a bench vise and tapping down with a drift. (If you bought new threaded inserts disregard this step.)
17) Line the spline dents on the threaded inserts up with the splines in the side gears you'll be using and tap them in until they feel "solid". (On new retainers there will be no spline dents.)
18) Put the side gears back into their respective sides of the carrier being careful that the thrust washers stay in place (if applicable).
19) Slide the spider gears back into their respective positions in the carrier being careful that the thrust washers stay in place (if applicable).
20) Put the spider pin back through the carrier lining up the match marks and line up the pin hole by eye.
21) Re-install the roll pin with a pin punch.
22) Line up the match marks and tap the ring gear back onto the carrier.
23) Install the ring gear bolts with lock tabs and torque them in a criss-cross pattern using three steps to come up to final torque.
24) Carefully bend the lock tabs back into position so the bolts can't back out.
25) If either (or both) carrier bearing(s) were loose on the carrier clean them and the carrier spuds with acetone and re-install with their shims (if applicable) on the carrier with Green Locktite (stud and bearing mount).
26) Slide the carrier assembly back into the housing.
27) Carefully install one bearing retainer loosely making sure the match marks line up and the shims stay put. Don't force it!
28) Carefully install the other bearing retainer loosely making sure the match marks line up and the shims stay put. You may need to wiggle the carrier and rotate the pinion gear a little to get this retainer to seat. Don't force it!
29) Install the retainer bolts finger tight and check to be sure the carrier turns freely with the bearing retainers and shims fully seated.
30) Tighten the retainer bolts and check to be sure the carrier turns freely.
31) Put a dab of grease on the O-ring on each stub axle retainer bolt.
32) Install the stub axles and tighten their retainer bolts. Be sure the O-rings go smoothly into the chamfer in the stub axle face.
33) Clean the rear cover gasket surfaces and install the rear cover with a new (dry) gasket or Nissan silicone. If you don't want it to EVER leak (even with synthetic oil) use Nissan silicone and no gasket.
34) If applicable, wait an hour so the Nissan silicone has set up.
35) Add the diff lube of your choice. It's much easier to do on the bench than in the car!
You're done!
If you use this method EVERY part will go back together EXACTLY the way it was before so the diffs longevity will not be in any way effected by disassembly and reassembly.
Notes:
1) This procedure works for R160s, R180s, R190s, and R200s.
2) R160 and R180 side gear threaded inserts are interchangeable.
3) R160 and R180 stub axles will interchange if you cut the dust covers off.
4) Nothing from an R200 will interchange with an R160 or R180.
5) Nissan silicone is about $20 a tube but is one of the best investments you will ever make. This stuff is so good that Nissan no longer uses oil pan gaskets on any of it's engines. Also, it will not harden in the tube like the crap they sell at virtually all auto parts stores.
