Discs Or Drums?

[Davey]

Hi Adrian, sorry I didn't explain it very well. In old cars with drum brakes all round you'd have twin leading shoes on the front for maximum braking effort and single leading/single trailing on the rear. Later cars with discs up front would typically have single leading/single trailing shoes on the rear. disc brakes require a lot more pedal effort to give the same braking force as a twin leading shoe drum setup hence the use of vacuum servos on disc braked cars. with a disc drum setup you should be fine for "normal" road use but as soon as you get on track the brakes take a real hammering.

I remember way back in 1980 we had a customer who was returning for new brake pads every week on his new XR2 under warranty, after week three "we" started to ask some bigger questions ("we" being the dealership management and "we" weren't even a Ford dealer). turned out he was doing some stage rallying at weekends and could totally trash a set of pads in 300 miles!

I've driven big vehicles and had brake fade after a relatively short (1/4 mile) but very steep (Wynnatts pass in North Derbyshire) descent and its just not funny arriving at your expected stopping point with no brakes !

Vehicle mass isn't everything, your brakes have to convert kinetic energy (movement) into heat energy and dissipate it to the air. The energy that has to be dissipated is not just related to mass but velocity as well. does a 500KG car travelling at 100MPH have more, less or the same energy to dissipate as a 1000KG car doing 50MPH?

D.