Originally Posted by The Black Count

A couple of months ago I came across the conversion brackets on eBay to fit focus rs mk1 brakes to a st170 and like lots of others bought them, then also bought the callipers from an Alfa Romeo and some brake hoses, I already had a pair of new disks. Took the st170 brakes off and went to fit the rs disks and hit a big problem, they do not fit as the bottom ball joint stops them fitting to the hub, pics show st170 brakes then the rs ones.

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I was unable to find much help on the web so tried a couple of things but the only answer that I know of is to fit a spacer behind the disk. I have gone through various wheel spacers and found that hub centric ones do not fit, the cheap universal ones sit very nice inside the disk but I ended up fitting solid universal ones 6mm thick. Going for 6mm is a compromise as when the car sits on the road the ball joint just touches the disk but gives 4mm of hub for the wheel to sit on and I have still had to take some metal from the joint to get clearance, using 7mm would clear the ball joint better but loose another 1mm from the centre of the hub where the wheel sits, going 5mm would mean taking more of the joint.

With the disk now fitted its time for the calliper, some metal needs to be removed to allow it to fit on the bottom and a big chunk taken out for the top, the same thickness of washers as that used on the spacer will need to be used to get the calliper in the correct place.

ST170 wheels do not fit!! the back of the spokes foul on the calliper but my 17inch OZ wheels do but they are et42 all irrelevant as I have some new ones
fitted. The rear axle spacers had to be removed first.

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