Willwood front brake conversionThe Sylva kit comes with solid discs and provision for HiSpec 4 pots. I decided that I wanted Willwood Midlite 4 Pot callipers and vented discs being an upgrade on what was designed. I have this configuration on my Westfield and I don't want lesser brake power on my Sylva compared to my Westfield SEIW. The front upright is straight out of the Triumph/Caterham parts bin being originally designed for a Spitfire.
Willwood make a conversion kit BK23K which includes discs, callipers, bolts and adaptor brackets. However they do not supply a set of fitting/modification instructions. The vendor merely gives the advice that "Wheel hub disc mounting face will need machining". In fact the vented disk provided is not even a good fit on the wheel hub, it is in fact off another car and the holes for the wheel hub have been added.
As supplied Caterham bits
The following information should help someone make the modifications without the head scratching I went through.
Process1) Remove the wheel hub, and remove the wheel bearings and studs (pressed into the machined alloy billet).
2) Mount the hub in the lathe and remove 2mm from the face that contacts the steel disc all the way down to the size of the disk inner hole. This from memory is 62mm. I don't recommend any more than 2mm as this will make the body of the 4 pot protrude beyond the wheel hub face.
3) Thoroughly clean the part of any swarf.
4) Machine the forged steel upright in the area of the steering mounting. This is tricky to set up in the mill (I used a cast iron angle mounted on the bed). Remove sufficient material to give you a gap between the rear of the vented disk and the steering arm attachment.
5) Reassemble all the stuff with the new disc in place, check for clearances.
6) Select shims (I used 2mm washers) on the mounting points of the calliper to centralise it relative to the new disc.
Modified using Willwood bracket
Due to a screw up by me at the early stages of trying to make sense of all this I decided for some reason to try and modify the mounting bracket. This resulted in a request to the vendor to get a replacement. He said yes sir that will be £80 + vat please. I looked at the part and decided it could be improved (too many parts, 3 parts into one) and not that difficult to make in the first place. Using my home modified CNC milling machine I put it to work.
I hope you have more luck than me making this modification, the information above should help.
ReferencesMotorsport Tools very helpful.