A longitudinally split brake system uses one master cylinder to operate the brakes on the left side of the vehicle and the other cylinder to operate brakes on the right. ... The compensating port acts to help keep the brake system full of fluid.

What is the purpose of a diagonally split brake system?

The diagonal split system, because it maintains braking ability for both a front and rear tire, is easier for the driver to control the vehicle in emergency brake failure.

What is the difference between a front rear or longitudinal split brake system and a diagonal split brake system?

A diagonal split is safer in the event of the failure of one circuit: it leaves you with one front brake, whereas a F/R split could leave you with rear brakes only, and a vastly longer stopping distance.