The Art of Tool Making Bruce Giller

Ever since I have owned my 1986 Spider, the differential has been slowly leaking gear oil; the bottom was covered with a gummy covering of oil/dirt/sand/bugs - something like almost-hardened jello. Over the intervening years, the leak has slowly but steadily increased in volume. I was topping it off twice a year which is way too much for me. Last summer I decided that it was time that I fix this pesky problem.

At the Tech Session at Star Automotive in Baltimore, a friendly Alfa mechanic was pointing out problem areas on the underbelly of a late model Spider. I asked about rear end leaks and he said that 99.99% of them originated at the seal where the driveshaft is bolted to the rear end. He said that it is usually caused by worn U-joints which cause an oscillation of the driveshaft and distort the seal. I have already had such U-joints but I think that the previous owner allowed worn U-joints to remain in service a bit too long. I asked how hard it was to replace the seal and he said it was Easy (a four letter word!); unbolt the drive shaft, remove the pinion nut and flange, pull out the seal, replace with new seal, replace flange, and torque down the pinion nut. He said that it would be even Easier (there it is again!) to remove the pinion nut with an air wrench; and I had a new one I wanted to try out.

I ordered a seal and bought some Mobil 1 gear oil, and on a warm spring day, I drove the rear wheels up on ramps and started to work. I unbolted the driveshaft from the differential and had a look at what was underneath the flange. What kind of strange nut was this?? The sides were smooth without any flats and instead there were notches cut out. I could see why; there just isn't enough room in the space to get a regular socket in. I discovered that the strange nut was called a ring nut. I looked in my manual and saw that there was a special Alfa tool (A.5.0114) needed to remove the nut; I assumed that it was just a socket of a certain size that I could buy at Sears or an auto parts store.

I begun my Hunt for the Elusive Ring Nut Socket. I knew that I couldn't rent this tool anywhere, so I inquired on the Italian-cars-digest on the Internet if anyone had such a tool. No one did but one guy said that he had made one from a large, castellated nut; he ground down the castellations until they fit. I bought a replacement ring nut (bloody expensive) to use as a template and scoured the hardware stores for such a castellated nut. I never found one of the correct size, for they were all too small. Then I decided that I might as well buy the socket. I called Rosanova Alfa and placed an order for one. A week or so later I got a call from them saying that Alfa no longer sells that tool! Then I called some other dealers on the Eastern seaboard to see if they might have one in stock, but to no avail; they all came back to say that Alfa no longer sold it. I called a few mailorder places but they never carried the socket in the first place. One guy said that maybe I'd get lucky and find a mechanic who was willing to sell it to me...on his death bed maybe!

Then I realized that I had missed a valuable local resource, the Alfantics! I contacted Jack Chesley, our esteemed Librarian and he said that there wasn't a ring nut socket in the chapter's tool library. At the chapter's Summer Cookout at Bill Oliverio's, I canvassed several people about the socket and only found one person who had one and he had made it himself. He said that I was welcome to borrow it, but I decided that I'd like to emulate our Neanderthal ancestors, and make the tool.

I stopped by Milano Motors to get some parts and told Julio my sad, sad story, and graciously, he lent me his as a template (he did say that I'd have to leave town if I broke or lost it...). I found out that there are several pinion ring nuts and the only difference is the spacing of the notches.

I measured the diameter of Julio's socket and then went to Trak Auto with my trusty calipers.It turned out that a $6, 30mm, 1/2" drive, chrome socket was the right size (it was just a bit smaller). I placed the two sockets together, opening to opening, and transferred the location of each 'tooth' as well as its' height. To insure that each tooth had enough thickness, I made sure that each tooth was located on the center of one of the socket's flats. I could have used the ring nut as a template, but it was easier using Julio's socket.

Using a 4", right angle grinder, I removed the waste between each tooth. I thought that I'd be there for quite awhile grinding away, but it went pretty quickly. The grinder wasn't able to get into the corners, so I used a metal file to square up the sides and bottom of each tooth as well as the gap between each tooth. The socket wall thickness was greater than depth of the ring nuts' notches, so I chucked a small, grinding cylinder in my drill press, and ground away the extra thickness from the inside of the socket (the original socket was done in same manner). I then trial-fitted the ring nut to the socket, using the file on the teeth until a smooth fit was obtained. I spent about 3 hours all told making the socket.

The next nice weekend, the car up on ramps and with the ring nut exposed, I put my new tool to the test. I put it on my air wrench and the old ring nut came off as nice as you please. After replacing the seal (and getting coated with dripping gear oil), I torqued the new pinion nut back on. Now, my Spider's rear end is clean and dry, as it should be. I returned Julio's socket and mine is resting in my tool case ready to called to service in the future. It is nice working with a tool that you made; it makes me feel more like a mechanic and less like a parts-replacer.

Capital page

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1996