by John Hertzman
Someone asked about trailer hitches for Spiders, “to pull a very small utility trailer just large emough for 4 tire and a tote box.” One reply suggested it would be difficult to fabricate something effective because of the lack of structure to bolt things to. Difficulty is relative—there is “enough” structure, I believe, and it isn’t a big job.
The structure of a post-roundtail spider is basically similar to the two cars for which I built very simple, very heavy duty hitches -- a Giulia Super and a 1972 Berlina. The details differed, because of materials I had at hand, but the principles were the same. The core of the hitch was a fore-and-aft member (a square tube in one case, a “T” in the other) bolted, with simple lateral brackets and appropriate load-spreading washers, to the bottom of the spare tire well. This transmitted fore-and-aft loads into the floor pan. At the front a virtual triangle linked that member to the upturned floor directly behind the differential; at the rear of the body another virtual triangle descended from the rear bulkhead (the “transom” of a Spider) behind the bumper to the fore-and-aft member. The triangulation was sufficient that to move the hitch either laterally or vertically the entire rear body would have to twist as a unit. No torsional loads were transmitted to any smaller sections.
In both cases the hitches were Reese compensating hitches, fairly brutal devices, and the load was a live-in travel trailer my wife and I used for about 50,000 miles in an extended period of sloth and indolence in Europe. I never weighed the trailer, but we normally had, besides basic living quarters, a fair wine cellar, decent kitchen, working darkroom, electric typewriter (yes, this was before computers), shortwave radio and tapedeck, and a fair library, so the whole shebang certainly weighed considerably more than the car. (And Alfas make ideal tow-cars, but that is another story.)
For a light-duty application the job should be far more simple. A virtual triangle dropping behind the bumper would support the rear end of a bar or tube extending to the spare well, and forget about the front half.
If you just want a small trailer just large emough for 4 tires and a tote box, the deDion rear axle out of any Alfetta makes a good base for a tire trailer, and there are plenty of beyond-salvage Alfettas around.