Now that I am able to but on Brembo Front calipers on my X-type, I am looking further into putting Brembo's on the back.

- I found out that rear STR calipers and the rear XKR brembo calipers have the same bolt spacing as the stock X-type rear caliper.
- The caliper offset is way off so spacers or a different offset rotor will be needed.
- The rotors on STRs and X-types are both 1/2" wide solid discs. (Silverstone XKR use wider rotors. Appear to be 20mm wide.)
-Parking brake will be an issue. (Jaguar rear Brembo's don't have parking brake capability.

I'm going to investigate further as I have time. I purchased a pair of Tesla rear Brembo electric parking brakes and will see if I can make a bracket to mount them. Then I wont have to figure out parking brake cables and can use a push putton to energize the parking calipers.

 

I don't know if this would necessarily work, but could you pull the rear calipers from say an STR and bolt them on using the S-Type rotor. If you transfer the whole system, it may work. Just not sure if the spacing side to side would work. The rotors use the same bolt pattern, so, the matter of the rotor fitting on to the axle I don't think would be an issue. May be able to even use say the XJR or XKR units.

 

Unfortunately a little more complex.
Rear X-type rotors are 280 Diameter with 63.5 reg, H =32, thick = 12mm (Solid rotor)
STR = 330 Diameter, Reg 64.3, H =42 thick = 15mm (Solid rotor)
S-type 3.0 = 298 diameter, Reg 64.3 H = 32 (Same) but 20mm thick vented.

I haven't run the calculations yet, but the Brembo rear piston area will be greater plus using a 330 rotor will likely drive too much rear brake bias.

Going with a 300mm rear S-type rotor and using the Silverstone rear Brembos (The use 20mm wide rotors) may be the best possibility.

For any of the combinations, I suspect that a caliper mounting adapter bracket will be required to get the Brembo to fit around either a 280 or 300 rotor.

I'll look at 2010 Camero SS rear Brembo calipers. They have a different piston area than the Jag rear Brembos, that might work out better. (Assuming I will need an adapter to mount the calipers.)

- I don't like the larger registration hub centric hole in the S-type rotors than the X-type, Can be a PITA to get them centered without a centering ring.

I'll run the math and try to achieve a 15 to 20% breaking force increase similar to the front brembo set-up.

I am more worried about fitting a parking brake. The Tesla calipers are for 20mm wide rotors.