I've just returned to this site entirely because of this post. I recently replaced the obsolete Detroit driveline in the front of my '63 WD200 with a slightly newer unit from a less than fortunate Ford. As a result, I've spent the last several weeks searching & researching this "I can't lube the $%^* U-Joint" problem. This post is one that I read during that research and, now that I've found THE solution, I thought I would come back here and share what I found.
My Dad had a grease gun w/a slim tip for just such situations. It was something that he "picked up" in his Sea Bee days during WWII and was used for reaching zerks in "tight spots" on certain pieces of equipment. It worked perfectly for these situations. Of course, when needed, I could find neither it nor anyone who knew what I was trying to describe.
As a practical matter, I am not the least bit opposed to "grinding down" a standard tip, or preferably, chucking one into the lathe and *turning* it down. Never-the-less, knowing that there is a tool *made* for the job, I at least wanted to find one to prove that they existed -- even if it turned out to be an antique and beyond my budget to procure such.
Well, at long last, I have tracked it down! For once, the Internet was virtually no help -- at least I could not come up with a search that would cough up the device. Once, I knew a manufacturer and part number, however, that was another matter...
So, if you don't want to "make do" with a "needle tip" (designed for a different type of lubrication system) or bother grinding down a regular tip (where do all those metal filings go anyway?), the answer is: Lincoln part number 5855.
Do a Froogle search on "Lincoln" and "5855" or on "LNC5855" and you should find it.
Once I had a part number, I was able to buy one from a local hose shop (not auto parts store -- they were clueless!).
Anyway, check it out.
You'll need a nail set or similar small punch to be sure that the zerk is "open" (id est, something small & round with a flat end to push, not "pound," open the little ball in the end of the zerk) before you start, Also, cleanliness is a must -- a little rogue grease, especially high pressure grease, will make the seal leak. Once you get the housekeeping out of the way, this thing works like a champ. Best of all, it requires no more clearance than the diameter of the head of the Zerk.
If you have a little more clearance and want a gasket seal to go with it, check out Lincoln Part Number 5859 (LNC5859). It is a right angle adapter, but the very tip is a threaded device that could be transferred to a straight tube. It is slightly larger than the head of a zerk, but has a rubber gasket so requires less pressure to force grease the right direction.
These two devices each cost me $19 locally. The Internet had them cheaper, but not by the time you add shipping & handling. Some Internet sites wanted nearly twice the price; caveat emptor.
I should probably mention that these are "adapters" which fit onto the end of a standard grease gun. They actually have zerks at the back end. You can move them from gun to gun, purge the grease, and use them in different applications more easily than if they were permanently attached to the gun.
On the other hand, if you unscrew the zerks from the back side, you'll find them to be the large variety and the holes left behind have threads compatible with the threads on the end of the typical grease gun hose. Permanent attachment to a one-handed grease gun would be ideal for most driveline situations. My Dad, for example, had the actual fittings right on the end of the gun itself. It may be that he did such a "transplant" to have just what he wanted.
Oh, and in my search, I found grease guns designed for "older Fords" (such as the Model T) that had small diameter, straight tube, gasketed tips. They would probably work too; but, at the price being asked, I wanted to hold the product in my hand and examine it prior to purchase!
Clayton, WA 99110