I've used 3/16" copper lines, and (mostly) M10x1 fittings.
The MX5 master cylinder is quite nice as it has 3 outputs - 2 for the front lines and one for the rear.
I've stuck a T-piece in the rear line to attach a Mk1 VW Polo brake switch for the brake light.
Following that in the rear line is a Mondeo reduction valve to reduce bias to the rear (Ford Part# 1113275).
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UPDATE: I had to remove the bias valve to get through IVA. With the valve in place the rear brakes were doing bugger all and I failed on overall braking efficiency.
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At the end of the tunnel is another T-piece to split the rear line to the rear calipers.
I got the front flexi lines from Furore. Was very impressed with their service, they were custom made and arrived next day!
Specs were:
400mm long, M10x1 female swivel with 15 degree bend one end, and 10mm banjo the other.
Probably ordered them slightly too long if I'm honest, but hopefully that won't cause me any problems.
For the rear flexis I'm going to use the MX5 ones for now as they fit nicely and I'm feeling a bit poor at the moment.
I've used male-male bulkhead fittings from motorsport-tools.com (part MSTRD1541) for the transition between copper and flexi lines.
