I have an 87 XJS which was rebuilt into a race car - inspired by the legendary TWR car of the 80's. The accumulator/motor doesn't work, as a result I have to stand on the pedal to try and stop the car. What can I do to replace the system and get brake boosting?

 

If your car is non-ABS then replace the brake servo (booster) after you have checked if it is connected to the correct vacuum source and holding vacuum.