After receiving my repaired nosecone from Caterham, I turned my attention to preventing a reoccurrence. This meant I had to increase the gap between the the expansion tank cap and the nosecone.
Obviously my first thoughts were to check my positioning of the expansion tank bracket; maybe I had positioned it incorrectly. The new manual (v1.2 and v2.0) had no reference to the precise position, but the old manual does have the following paragraph:
UPDATE – In v2.0 of the build manual, it shows the expansion tank bracket bolted to the non centred, non captive nut hole. This increase clearance with the nosecone.
”A measurement of 135mm should be marked for the first riveting point, from the centre of the cross-member intersection to along the forward-most tube (RHS of the engine bay)”
My expansion tank mounting plate was within 1mm of that measurement. Considering I didn’t use this measurement when fitting the bracket I was happy with that.
Therefore the only option left to lower the cap from the nosecone was to modify the expansion tank as per my observation from the factory built 420R. I took the lip off the bottom the expansion tank with a Dremel and cleaned the cut with some sandpaper.
Refitting the expansion tank and nosecone to ensure the gap had increased, I realised I could increase the gap even further by fitting a small spacer between mounting bracket and the expansion tank. This did require a slightly longer bolt.
Measuring the gap between the nose cone and the expansion tank cap isn’t easy, and maybe not having a good technique lead to my initial problems. This time I wanted to prove I had increased the gap, instead of just a estimating. My solution was blue tack, but any clean putty type stuff would do. I pressed it into the gap, removed it and measured the difference. I have increased the gap from less than 5mm to a little over 10mm.