An attempt was made to fit the same brake calipers that are on the Escort front to the XR4. Twin pistons with 300mm rotors.
Small interference fit between the caliper and back face of the wheel. It rotates between the carrier arms!
Commode VT calipers are the same bolt spacing as the XR4 so the mounting bracket thickness could be omitted and gain clearance but a bit of research suggests that the XR4 mastercylinder would most likely struggle with the increased piston area. The ST170 Focus uses 300mm rotors with the same size single piston sliding caliper as the XR4 with a different carrier.
A bit of a look at the XR4 calipers shows that the carriers could be drilled and tapped to suit a larger rotor with the old holes filled. A bit of drillium later and it should work.
Grabbing a rotor later this week and if ok I will do the two on the car.
Only about 8% more braking torque but better heat dissipation through the larger rotor volume and the ST170 pads which should also fit have larger contact area.
In Escort news I picked up an AU XR6 Watts link diff cover and linkages and these will be test fitted next week. The chassis rails on the Escort are naturally narrower than the AU so I am thinking of cutting the link rods and adding a length of threaded bar and making the width adjustable. Similarly making the body mounts with multiple mounting holes so the links can be set up horizontally at normal ride heght.