Rover SD1 EFI, Vitesse Brake conversion - SD1 - Jaguar XJ6, XJS

The Rover SD1 vanden Plas models are supplied with 258 mm solids brake discs at the front of the car. The brakes operated by 4 pot calibers as on the Vitesses, the only difference is that the Vitesse and EFI models use ventilated discs. And to be honest it does the job, but for a car that weighs 1400 kg heavy braking at speeds of about 200 km per hour is somewhat difficult. It is a bit underestimated, and would normally work well on a 900kg car.

A big improvement here is to convert the Vitesse brakes to Jaguar brakes. These are the 285x24 mm ventilated discs with Girling single circuit four pot calibers. These calibers pistons have the same diameter as the 1986 EFI and Vitesse

The brake pads from the Jaguar are around 1.5 times the size of the Vitesse so there is a large improvement. This setup came from the Jaguar XJS V12 (1978 models) and is no problem to get the parts. Even some XJ6 models with 4.2 engine use these brakes.

For adopting the Jaguar discs onto the Rover wheel hub there is a converter plated needed. This plate can me made of steel, and if you don’t have the technical skills to do this yourself, a mechanical can do the job for you on a latch. The adapter plate is made to a 2/100 mm tolerance in thickness.

Below a drawing of the adapter plate with the required dimensions.

The plate will be fitted between the disc and the wheel hub. The brake caliber mounting is about the same thickness as the end of the steering arm, which is normally mounted over the brake caliber.