Ring & pinion clearances, tight or loose?

[handfulz28]

Just wondering if there's a preference for setting up differentials. I'm guessing setting up on the loose end of the factory specs will help it run a little cooler?
But even though we're talking thous of an inch, could the loose set up cause any damage or ill effects?
Thanks,
Michael

[Eric Parham]

I'm no expert. Although setting up loose certainly reduces temperatures, the better approach is to run it in (e.g., on a street car if available) to wear down all the high spots. On how much is too loose, you'd have to consider that although looser reduces friction and heat, it also leads to higher shock forces due to the abrupt take-up of clearances. If the diff has more strength than you'll ever use, then loose is probably best, but if the diff strength is marginal in your application, you might want to stay a bit tighter and do something else to reduce temps (i.e., run-in, special lube or additive, diff cooler, etc.).