The Good with the Bad
As mentioned in the introduction, it was critical to me that I got an early version of the F355, due to the “stronger motor”, but again there was a design weakness that seems to have slipped out on the first few models, and one of the big ones is on the early subframes : the lack of a gusset on the upper front wishbone bracket. This creates a stress riser at the perpendicular intersection where the bracket and the subframe are joined by a weld. Very soon following the launch, Ferrari added the gusset, so it is only the very early cars that have this weak joint. Fortunately this is a “fix once and forget” issue.
The reason that I researched this “feature” was because there was a weld repair on the subframe on the SX side, and I quickly noticed that most other subframes had a gusset in this area. Close inspection of the DX side revealed as well (after paint removal) that a very small crack had indeed started in the same spot. The repair on the SX side was not at all pretty, but to be fair, it was doing the job and did not fail. Nevertheless, a true repair was in order as the weld was only a band-aid, the stress riser was still there. I laser cut some gussets to weld in, and also made some braces to reinforce the sides of the frame where the crack had propagated. Need to give an huge shout out to my friend Alex Buchka (@242fakeracecar) for making all the nice welds, and showing me how to use lathes and mills to make tools.
The other item that I wanted to repair on the subframe was the cross member that runs underneath the transmission. This part inevitably gets assaulted by a floor jack at some point in it’s life and the span of box steel is nowhere near rigid enough to lift the car, so it gets bent. As the span is right between the lower wishbone mounts, bending the cross member should theoretically alter the rear suspension geometry as well, therefore is important that the replacement length is the same. I ended up purchasing a section of 20mm x 50mm box section, building a jig and then cutting out the damaged box section and welding in the new box section. Trying to find 20mm x 50mm box section in the USA proved to be quite difficult, so I had a friend bring a section from France in his suitcase, when he came over for a visit (strange suitcase contents, but I’m sure customs has seen stranger things!). Again very happy with the welds and overall result. The only evidence of the repair is the fact that the welds are nice tidy TIG welds, and I am perfectly OK with this “non-originality” :-)
Once the repairs were done, I had the subframe refinished in a textured powdercoat. I must say I am very pleased with the finish. Being powdercoat, it is harder than the original finish, but the texture in real life, is very very close to the orignal. I’ve got no complaints about the durability of the original finish, it was in very good condition, and in fact was a shame to strip off, but the welding involved with the gusset repair necessitated the refinishing. The end result is a perfect and very durable finish, nicely welded gussets, and a straight cross member under the transmission.
