As folks upgrade OE calipers, their cast offs can often be an upgrade for someone else. However, a caliper upgrade is not just a simple fit and go because you need to consider your master cylinder ratio so you have optimum performance. Is there a chart or general information available that offers guidance about which master cylinder to use with a given caliper ? Andy
Unless you're upgrading from a single disk to a twin disk, your existing master cylinder will work fine. If you are upgrading to a radial master cylinder then you will want to consider the ratio of the lever. The bore size of the cylinder itself should be the same as you are currently using - normally it's 19mm bore for twin and 16mm bore for single disk setups. Brembo radial masters usually come in 18, 19 or 20 ratio. The different ratios effect the feel at the lever as it's to do with the distance (in mm) between the pivot point of the lever and the actuating pin/plunger. A 20 ratio will feel firmer but give more "feel" whereas an 18 ratio will feel softer but give less "feel" at the lever. Most of the radial masters available now can be bought with adjustable ratio levers, meaning that you can cycle between ratios using a clever cam system built into the lever. Brembo's RCS system allow you to switch between 20, 19 and 18 ratios. Accossato also has the PRS system which can be switched through 19, 18 and 17 ratios. Replacement masters not cheap, and usually end up being a "fit and forget" item but they can make the brakes feel so much better than using the original OEM item. And they look blingy! Don't forget that most aftermarket radial ("race") masters won't have provision for a brake light switch, but you can buy a hydraulic switch that replaces the banjo bolt and can be wired in place of the brake switch. You may also have issues with the output from the master as this can be in a different place to non-radial masters and may cause clearance issues. Again this can be solved using right-angle adapters that allow you to remount the banjo. Mounting a reservoir may also be an issue if your existing master has an integrated mount, or provision for a bracket, but again there are ways to solve this. For more info: Master Cylinders | Brembo - Official Website
