An interesting read Paul and for what it's worth I think your analysis is essentially right.
Friction materials are tested exhaustively on dynamometers and actually deliver a considerable range of friction coefficients depending on the specific conditions of speed, temperature, humidity, pre-conditioning, etc. And guess which value the supplier likes to quote? Even though it may only occur under very specific circumstances.
Just how much analysis suppliers do on 'vintage' materials I wonder; it's not a huge market and probably doesn't have the budget OE applications command. Rather I suspect they supply what the majority of people ask them for. Even in the modern car industry, material selection is largely a question of what worked well on the last model, it is (for good reason) a very conservative business.
The area you might explore if taking this study further is the geometry of the drum brake itself. Many configurations were conceived 'back in the day' to deliver ever more 'self servo'. It's a road fraught with peril though, as the higher you push the output the further it has to fall. The fundamental reason drum brakes were almost entirely superseded by discs is stability; they are not more powerful than drums but continue to deliver a more or less steady brake torque when the nearest drum brake car is parked somewhere in the hedge. Maybe less a worry for sprints and hill climbs where there isn't time to cook them properly.
Yes, and tyres. It is more or less a given nowadays that - with the help of ABS - the brakes are capable of locking the wheels, so stopping distance in the modern world is all about tyre compounds.
Friction materials are tested exhaustively on dynamometers and actually deliver a considerable range of friction coefficients depending on the specific conditions of speed, temperature, humidity, pre-conditioning, etc. And guess which value the supplier likes to quote? Even though it may only occur under very specific circumstances.
Just how much analysis suppliers do on 'vintage' materials I wonder; it's not a huge market and probably doesn't have the budget OE applications command. Rather I suspect they supply what the majority of people ask them for. Even in the modern car industry, material selection is largely a question of what worked well on the last model, it is (for good reason) a very conservative business.
The area you might explore if taking this study further is the geometry of the drum brake itself. Many configurations were conceived 'back in the day' to deliver ever more 'self servo'. It's a road fraught with peril though, as the higher you push the output the further it has to fall. The fundamental reason drum brakes were almost entirely superseded by discs is stability; they are not more powerful than drums but continue to deliver a more or less steady brake torque when the nearest drum brake car is parked somewhere in the hedge. Maybe less a worry for sprints and hill climbs where there isn't time to cook them properly.
Yes, and tyres. It is more or less a given nowadays that - with the help of ABS - the brakes are capable of locking the wheels, so stopping distance in the modern world is all about tyre compounds.