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Hello Guys, since last weekend I´m owning a 280z which will be fully restored and therefore I`ll change every component that was/is in contact with fluids or has orings inside. Especially the brake system. So when buying new parts I also could just spend a little more and get "better" parts. So the idea came up for a brake upgrade. I was reading a lot of threads about rear disc conversion in a couple of forums together with the problems that go along with it (brake bias, not for this stress designed axels etc.) Together with the fact that I`m out of germany and its not that easy to get it road legal with a disc brake where normally a drum sits. I was deciding to leave the stock drums and just get new pads, hardware and wheel cylinders for the back. In the front I`d like to install a vented disc setup. That this setup works well was backed by the nissan competition catalog were as far as my understanding goes they installed a 4 piston caliper with 41,3 mm dia (FIA MK63 brake) a vented disc and changed the rear drum wheel cylinders to 13/16". Nothing else was touched - is that right? So stock proportion valve, stock 7/8 master. My problem is I can`t find anybody who did this swap before due to the fact that everybody goes straight to a rear disc conversion which I don`t wanna do. So seems that two upgrades would be possible for me. The vented S12-8 from a 88 L4 4runner with vented discs (couldn`t find a kit online) with two 43 and two 34 mm dia pistons in each caliper which seems to work good with a rear disc setup. Or the S12-W conversion with four 43 mm dia pistons. If you go through the other threads a lot of people say that the S12-W is really heavy but I couldn`t find any numbers. Wheel clearance wise the S12-8 vented should also be better than the S12-W. So what we know is that the original nissan upgrade works well. To check the bias change I was trying to do some calculations based off the premises you don`t change pad compound, leave the rear drum alone (besides the piston dia on the FIA brake). So as these values would be all the same you can remove them from the calculations - right? Question is only by how much a little bit bigger padarea would make a difference and also a couple mm bigger dia disc would make a difference. What I did is not the REAL brake bias but I guess its a good starting point to only compare these three systems to each other. Or what do you think? So the FIA Brakes are 4 piston with 41,3 mm dia the rear drum cylinder are 13/16" so 20,6375 mm dia. So in total you`ve 8 pistons up front which combined have 10717,168mm² while the backs are two pistons each side so four in total with 2676,048 mm² together. S12W are 43 mm dia and stock 280z rear drum cylinder are 7/8 so 22,225 mm dia. Same number of pistons so up front 11617,608 mm² and rear 3103,584 mm². S12-8 vented has 4 pistons 43 and 4 with 34 mm that makes 9440,484 mm² plus the same in the rear like one above with 3103,584 mm² That makes a 80/20 distribution with the MK63 FIA brakes and 78,9/21,1 with the S12W and stock drums 75/25 with S12-8 vented Mounting points are the same so you don`t have different leaver. Considering you run the same pad compounds. Which have almost the same dimensions as well. You also should have the same pressure because they are not changing the master. Which I probably would due to the necessity of more fluid - so a 15/16 master would probably go in. Seems that the S12W is a pretty close call compared to the original vented upgrade with MK63 and 13/16" rear drum cylinders. What do you think? A manual willwood proportion valve (the black one) could also get rid of that 1% difference and would remove a tiny bit line clutter in the engine bay. Is someone running that setup and has some rekomendations or experience? Because you can talk and calculate a lot, but when it is not even noticeable in the end...IDK. The car will go down the performance road, so upgraded suspension, wider wheels, overfender, around 200 HP (hopefully) etc. BTW out of jdmjunkies.ch: MK63 Solid disk type including brake-pads: 4.300 KgsStandard two pot OEM including brake-pads: 4.445 Kgs what I found on an other side is 3,8 kg for the vented MK63 without pads - not really comparable. And I did`t find anything about the S12W or vented S12-8... Thanks for your help, much appreciated