by Mike Robinson » Fri Jul 07, 2017 9:38 pm
A few words about our Viva conversion to go with the photos. I bought it in 1978 specifically to make it into a drophead for my wife. It was a 1256 “fleet” model and very basic, although there was a heater and it was undersealed. It was cheap too, I found out why later when I had to rebuild the engine!
It’s really difficult with convertibles derived from monocoque cars, to make them stiff enough in torsion - an easy stiffness test is, can you jack up one corner and still open and close the doors freely. I had a chance to look round Crayford’s workshop (even some of theirs had a reputation for being a bit “flexible”) to see how they did the conversions. I found that they needed to hold a car on a jig while they cut away the inner sills and parts of the floor pan to weld in substantial box members between “A” post and rear wheel arch, and decided that was a bit too challenging for me and my stick welder. Remember this was before small diy level MIG welders became available. I did some calculations and some crude model tests and realised though that keeping, and perhaps strengthening, the over door members would allow an easier, workable design.
I treated it first to a commercial “steam clean” actually a high pressure hot water blast which revealed a lot of rust holes in the wings of a seven year old car but made it a lot more pleasant and easier to work on, then drove it into my single garage, kicked out the rear windows, and picked up a hacksaw and cut off the roof. No going back then!!
The basic reinforcing includes the roll bar system together with a supplementary “B” post, transmitting loads into new inner panels between the “B” posts and rear wheel arches – where you have mill board covered in vinyl I have sheet steel. Based on some experience in the aircraft industry I hand cut and bent most of a 6ft x 4ft sheet of 19 gauge (just over 1mm) mild steel to make lots of shapes, brackets, stiffeners to put it all together. It’s also mainly glued and riveted together, with some carbon arc brazing ( a transient technology producing lots of fumes which was probably almost as unhealthy as spraying two pack without a mask) where needed.
The only bits I didn’t do myself were bending the roll bars and extra “B” post, the top coats of cellulose and the hood, which was cut and fitted to my frame. By comparison with the body, the hood was very hi-tech for the time and fully welded.
It has recently been treated to a professional respray and some new chrome so it looks rather smart. The hood also got a new window and some minor repairs. I had the engine out to cure most of the oil leaks, sorted out the wiring and other neglected areas a bit, and generally tarted up the interior with new carpets, resprayed upholstery and dashpad.
If I could only fix the flat spot on acceleration I would be happy with it!
Mike
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Last edited by
Mike Robinson on Mon Jul 10, 2017 9:28 pm, edited 1 time in total.