Originally Posted by
maxepower
Wow, I've been running my diff gears dry for a while
Although I think this is OK, I wouldn't try it with anything more powerful than a silvercan. Plastic gears do have natural lubricity but this only helps to a certain point, whereafter the friction and heat becomes greater as the load increases. I had a 1/8 OFNA Pirate wayyy back when which believe it or not had plastic ring gears. The gears wouldn't last dry but would handle the power easily with some Teflon gel grease I got from radio Shack.
Grease would be too heavy in this case though so something like a Heavy-duty spray silicone would be a better choice. It is very light but is very slippery and is designed to lubricate plastic and such. Even a Teflon dry film lubricant would be excellent.
If your track is dusty and are worried about grit getting into your gear box, just smear a very light film of any type of grease between the diff case halves, bearing saddles and anywhere dirt can get in through, before you put them together. This should seal the dust out.
Originally Posted by
maxepower
Most important is shimming them so it's not too tight and not too loose.
Yes, very important!
On a side note, if you did happen to accidently set the backlash too tight, here is where some sort of lube would be beneficial. Setting backlash should only be done with dry gears however.