A lot depends on what you plan to do with the car. The major difference between drum and disc brakes is the rate at which heat can be dissipated to the air. with drum brakes the shoes have no air flow over them and can very quickly overheat when used hard, discs on the other hand have much better airflow and that air also passes over the pads so keeping them cool for longer. Anyone who has ever experienced severe brake fade will almost certainly want discs all round.
There is another advantage to discs on the rear that may have escaped some of us. Drum brakes have a "self servo" action. What this means is that the leading shoe, once it contacts the rotating drum will tend to be pulled into tighter contact with it thereby increasing the braking effort without increasing pedal force. Disc brakes don't do this as they rely on clamping the rotating disc between the friction pads.
Anyone who is old enough to have driven cars from the sixties (or earlier) will probably remember that the brakes were crap going backwards, that's because the front brakes on an all drum system had a twin leading shoe setup. When leading shoes are run backwards they become trailing shoes and lose the "self servo" action. Moving on to disc braked cars I'm sure anyone who has been towed in a disc braked car will understand just how much pedal force is required when the vacuum servo isn't operating.
D.
|