1989 Pathfinder 4wd 3.0 L The alternator adjusting bracket bolt to block came out and we can't figure out what size it should be. An 8mm is to small and 10mm is to big. I have searched this forum everyway I know and cannot come up with a hit as to what size it should be. Anyone know for sure what it should be it apears the threads are still there. And the 8mm goes in clean doesn't touch anything on the sides.

 

High WT,

I'm assuming you haven't solved this yourself yet. I've been lookiing at my old screw thread tables and - bearing in mind the year of your Pathy - it could be a 3/8inch UNF or a 3/8 UNC. THe UNF will have 24 threads per inch, the UNC 16 so if you can see any thread left on the old bolt, measuring the number of threads per inch will confirm this. Out of interest, 3/8 inch relates to 9.6mm. If an 8mm bolt will slip into the hole without being screwed in, that suggests that it's 3/8 UNF. If it won't quite slip in, then it's more likely to be UNC. The reason is the UNC coarse thread is deeper than the UNF fine thread (UNified Coarse and UNified Fine)

You Yanks invented the UNF and UNC threads during the 2nd World War you know.... Let us know how you got on