I have a 92 YJ and there are a few ujoints on my driveshafts that have needle zerk fittings on the ends of the ujoints. I do have a needle fitting for my grease gun but have been unable to get the grease to enter any of the ujoints.
There is a little ball in the needle fitting that I am just pressing on with the tip of the needle to get it to move inwards. When I insert the needle the grease immediately just comes right back out of the entrance hole. I've tried entering at an angle with the same results.
What is the trick to greasing ujoints with needle fittings?