Thread: Can anyone tell me what this bolt head is? RRC starter motor

Both bolts came out pretty easy in the end, except for the obvious lack of space/leverage! 12mm - 12 point socket was the correct tool!. Thanks for all the help

Originally Posted by Meccles

I suspect that they had buckets of various bolts at factory and when building them there was a “whatever fits works” attitude. I removed the bolts on the brace at bottom of door window frame on my two door. Two bolts imperial headed 7/16. Third and most difficult to access - 10mm but with imperial thread. Who even made stuff like that?

Commonly found on after market fasteners of Oriental origin. Taiwan used to be notorious for these. Metric heads and UN threads and vice versa. I am sure they were made in the chicken shed by a rice farmer with a second hand capstan or turret lathe and whatever bar stock was to hand.

MG had some with BSW heads and metric threads before the MG A and the unholy alliance Morris and Austin to form BMC.