Whilst I have no reason to doubt the theory behind Dicks description
of the physics I still have to say that from a purely practical point
of view, the disc brake / dual M/C conversion on my '61 has made a
distinct improvement in the braking characteristics of the car. It is
not only the shorter stopping distance but the feel and sensitivity of the pedal
which has improved.
Now I will freely admit that by the time I did the conversion, I had
developed serious hot spots on the front drums which did nothing to improve
their stopping power. In addition, the improved sensitivity may be
partly due to the new M/C but even when the drums were perfect and all four
wheels were quite capable of locking up, there is no doubt in my mind that the
discs have been a major improvement. There seems to be more to braking than
simple friction. It is about how the car handles under sharp deceleration.
Perhaps some of this improvement arises from the necessary addition of a
proportioning valve that governs the pressure ratio between the front and rear
brakes.
Apart from the improved braking characteristics, the other advantage is
simpler maintenence. No more painstaking adjustments and fiddly bleeding. On the
downside, the dust from the pads turns your white wall tyres into gray walls in
no time at all. Easy enough to clean but annoying all the same.
Just some observations from someone who has direct experience of both
drums and discs.
Best wishes,
Tony V.
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