Quote:
Originally Posted by Armrer
Roger,
Consider these NOS Leverolls.. that accurate in all dimensions. Perhaps some pix of your car chassis would speed up the info flow?
Tracks come with no fasteners. That decision is up to you. SA crews brazed in countersunk headed fasteners right over the plating. Sometimes hex head bolts were brazed in as well, after the track was counter bored. I have a ton of pix from the originals that have a more than a few different type of fasteners used. Even seen stick welded threaded rod used.. not pretty!
Perhaps Dan can chime in with what he has in his research-
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1St things first. Your new track assemblies look fantastic. I could have put two sets to good use in 2016 on a friend’s car.
I will spare you the very long retelling of all that I have learned. In summary my conclusion is that AC Cars:
1) Had the supplier do it or did it themselves, the track fixing screw holes were chamfered for countersink headed set screws.
2) Installed ¼ BSW self finished carbon steel flat head countersink set screws from the cockpit side with a thin self colored (see note 1) hardened steel flat washer, a self colored split spiral lock washer, and a mid World War II specification (see note 2) onward self colored (in this case bare steel) full hex nut machined from bar stock with a single chamfered side (see note 3).
Note 1: Self colored fasteners normally means any finish (bare metal no protection, bare metal with
oil or grease protection, oxides from heat treatment and
oil, phosphates with or without added dye or
oil, or black coatings with or without added dye or oil) that were not electroplated onto the part. AC Cars wise there were hundreds of “self colored” fasteners in a Cobra.
Note 2: In my never ending hunt for original specification fasteners I found new old stock nuts machined from hex bar stock in two different versions of Imperial hexagon sizes. One of the vendors told me that during World War II the British government had their industries reduce the hexagonal bar cross section sizes downward to stretch steel supplies for the war effort. Said another way, you might find nuts on a given thread size that have two significantly different across the flats wrench sizes. If you have two nuts on the bench that require two different British wrench sizes you have one pre-war (larger of the two) and one war time onward (smaller of the two) in front of you. AC Cars used the mid World War II and onward hex sizes.
Note 3: There are many obsolete fasteners in an original Cobra that are extremely hard to find replacements for used or new old stock. One of them is the ¼ BSW single chamfer hex nuts machined from WWII onward Imperial hex bar stock. If you want to make some I can help with the details as I have hunted for a couple of years for some new ones worldwide and not found a single one.
Note 4: On an original car, having the inside rear screw permanently fixed in place makes removing and installing washers and nuts up against the chassis tube behind a gusset a tough job. If the screws are short it can be ultra hard. Done AC Cars way we can install a pair of seats in a few minutes. Done the way many been modified to can me putting nuts on just two screws can take several hours of struggling unless you start modifying the car’s chassis (which I will not do).