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Discussion Starter #1 (Edited)
As I use 16" wheels for racing and for winter I have made my own BBK for track and DD.
I use Porsche Cayman S/Boxster S/911 996 front calipers. They have exactly the same piston area as R56S/JCW stock calipers. So they have stock pedal travel and do not influence brake bias themselves. They have asymmetrical piston sizes for even pads' wear. 36/40 instead of 38/38 of JCW Brembo. The pads are thick and have big radial depth - 62 mm. JCW 4-pot pads have 55,6 mm, GP2 - 61 mm, AP Racing MINI 304x24 kit - 46 mm, AP Racing CP5200 and MINI Challenge calipers - 50 mm, Wilwood MINI 4-pot - 42,5 mm. The bigger radial depth is - the bigger actual friction surface of the disc is. The bigger actual friction surface is - the lower peak temperature of surface is.
I use 310x28 brake discs of Alfa Romeo 166. They have 63,25mm annulus and ideally fit the pads. I use Fremax discs. They have a bit wider air gap than Brembo (12,5 mm vs 12 mm) and lighter weight (8 kg vs 8,6 kg). JCW 316x22 discs have air gap 7 mm, GP2 330x26 discs have 9 mm. Also they are claimed to be high carbon. I don’t state that they are better than Brembo, but that is my choice. As all Alfa discs they are cheap.
To install Alfa discs I used spacers (stainless steel shims) between the hubs and the discs. The shims provide the required disc's position and protect the hubs from overheating.
Also these calipers can be used with 305x28 mm discs, if 310 are too big for certain 16" wheels. Probably some 16" could accommodate these calipers on 315x28 BMW M3 discs, my 16" require too big spacers.
Using the shims the position of the caliper can be adjusted in wide variety in axial and radial directions to install different discs. There is a bunch of variants. The maximum size of the brake disc which can be used with the stock 17" wheels is 330x28. GP2 330x26 discs fit fine and bolt-on. The most attractive but costly discs are 325x28 BMW M3 E46 discs. Custom 2-piece discs is another talk.
 

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Thanks, very good info, I really like the air gap benefit, I have already modified mine to accept GP2 size brakes, but still like this option, where did you get carriers? Were they already with the calipers? Bit of a faff re-drilling discs for me.
 

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Discussion Starter #5
Thanks, very good info, I really like the air gap benefit, I have already modified mine to accept GP2 size brakes, but still like this option, where did you get carriers? Were they already with the calipers? Bit of a faff re-drilling discs for me.
I made custom brackets and milled the calipers' mating faces. The calipers can be used minimum with 330 mm discs without milling.
 

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Discussion Starter #6
Here are the pictures of brackets. They are not for Porsche but for Alfa Romeo Brera/159 calipers, but they look almost the same. Those Alfa calipers were adopted just for fun. They are not the best choice for MINI since they have too big pistons (42/42), but they were installed on R53 where they are currently. And they don't fit in 16" on 310 discs.
 

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Wow those brackets are thin
 

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Mine are, not galv but en21 or 24 or something and way bigger, but still based on the Brembo part that came off. I suppose it looks different close up rather than pics, would make me nervous haha.
 
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