I have my front diff taken apart (D-25 in a 1953 M38A1 - same as CJ5) and have some questions as I am contemplating cleaning and re-build. I have the knuckles off, the driveshafts out, the diff carrier out (not taken apart), the pinion out (not taken apart). I've left the knuckle bearing cups in and the pinion cups in as they all look in good shape. I did the disassembly to inspect everything and replace old leaky seals (inner axle seals just outboard of the diff and the pinion seal as well as the knuckle seal) and gaskets and re-pack the wheel and knuckle bearings.
1. I have cleaned the outside and wire-brushed a lot of it, but I have a transmission shop down the street that I think will hot tank it for me to get in all of the nooks and crannies. Will hot tanking hurt the knuckle and pinion cups? Is there a better way to strip the outside in prep for paint? I want to avoid getting grit inside the housing as much as possible.
2. What is the preferred sealant (Permatex 300?) on:
- the outside rim of the oil seals
- the pinion yoke butt and splines
- the fill/drain plugs
- the bolts that go through housing through-holes (like the carrier bearing cap bolts)
3. What is the preferred sealant on the housing gasket?
4. What is the preferred gear oil? Is 85W-90 better than regular 90wt.?
5. I banged the pinion out with a block of wood per the manual - does this damage the outer pinion bearing or bearing cup? It looks and feels OK.
6. What is the preferred grease for the wheel bearings, axle joints, and knuckle? Ludel recommends Texaco Starplex-2 but I can't find it locally.
7. Is the paper gasket behind the pinion seal necessary?
8. How much pitting is OK on the knuckle external surfaces? What is the preferred way to fill pits - is JB weld or epoxy OK?
9. Can I take a couple of extra drive plates to a machine shop and have them machine out the splines so that all of the front axle internals aren't spinning - i.e. maintain the correct look (no lock-out hubs) but reduce front axle wear. Will that work? Drive plates are easy to swap when I want 4wd.
10. Is the diff cover vent fitting re-buildable or should I just buy a new one?
I am sure I will have more questions later!
1953 USMC M38A1
Restoration Blog: http://troy-m38a1.blogspot.com/