Originally Posted by
Grand Bois
There are no threads on my zerk or in the BB. It's a force fit. I drove it in with a hammer and small socket from my 1/4" drive set.
I didn't know they came unthreaded until I checked the McMaster-Carr site: sure enough, there are inch-size with serrated shafts down as small as to fit 1/8" hole, as well as some with smooth straight shafts for both inch and metric holes (but not smaller than M6).
http://www.mcmaster.com/#zerk-grease-fittings/=gh413u
good to know.