"Freshening up a differential"

[mdbrandy]

Ok, so I'm getting ready to go over the differential I just bought before I put it into my 280Z. I've ordered new pinion and halfshaft oil seals that I will use, and since the cover was off when I bought it, a new gasket too (although I just read one of our tech articles that recommends Nissan silicone for that "never leak" seal). The gears seem to turn freely and smoothly, but I don't have any experience with working on the inside of a differential, so I don't really know what I'm looking for. I read the FSM section on servicing the R200, and while the diff itself seems reasonably simple, there appear to be a plethora of special tools recommended to set clearences, preloads, etc., that I don't have. So I really don't want to take it apart myself. The question is, should it be taken apart?

My goal is to "freshen it up" so that I don't have to worry about it for many miles to come. New seals are a no-brainer, but what about bearings? I have no history on this diff. Without taking it apart, can I tell what condition the bearings are in? The teeth on the gears look fine as far as I can tell, although I'll inspect them more closely tomorrow. Are there some set of measurements that I could have a shop with the right equipment (I don't even have a dial guage yet) do that would diagnose any normal problems? Three things that the FSM say to do that don't require dissassembly seem to be pinion preload, ring/pinion backlash, and the tooth contact pattern. Would those measurements be enough to really tell the condition of the unit?

Thanks in advance for your expert advice :classic: !

[2ManyZs]

I guess they could check for lateral run out on the output shafts to check the bearings.

The R-200's are a PITA to set up because they use shims to adjust the preload on the pinion. I had an ex-Nissan tech do mine, and he said he'd rather work on an R-180 anyday.

I'd just clean it out good, and take it to a shop with a dial indicator and ask if they can check for any lateral play in the pinion shaft or output shafts that could indicate worn bearings.

Since you say the ring gear isn't worn or have any grooves from the pinion gear, I'd say it possible that everything is OK. Any wear in the bearings would show up as uneven wear or galling in the ring gear face.

[mdbrandy]

Ok, to continue this thread... I've been exploring the diff, and I have one potential problem, and a few pics. The potential problem is that the RH flange and shaft has a lot of runout and movement compared to the LH (the LH essentially doesn't move at all in, out, or laterally). The RH shaft will move in and out 0.05 inch or more. In the picutre I've attached here, you can see a small gap between the thrust washer and the gear carrier when I push the shaft all the way in. In the next picture, you can see it closed as I pull the shaft outward. The whole assembly kind of "rocks" a little too. The third pic is of the RH bearing. Note that as I "rock" the shaft and/or pull it in or out, the rollers in the bearing don't move at all. Maybe I don't fully understand the geometry. Finally, is a pic of the ring gear teeth.

Nice to be able to upload multiple pictures! Yeah!

[mdbrandy]

Further question: the inside of the diff has a little bit of grit and dirt due to being stored open for some period of time. Do I have to flush it out with oil, or could I use some sort of solvent without hurting it? I'm replacing the seals anyway....