Hobson wrote:
An interesting little tidbit I found when looking at my disk conversion for my 998, preparing for when I actually find a 1275.
https://www.sgi.sk.ca/air-brake/-/knowl ... t-distanceThe distance required to stop a vehicle depends on its speed and weight in addition to the factors of energy, heat and friction. The brake power required to stop a vehicle varies directly with its weight and the “square” of its speed. For example, if weight is doubled, stopping power must be doubled to stop in the same distance. If speed is doubled, stopping power must be increased four times to stop in the same distance. When weight and speed are both doubled, stopping power must be increased eight times to stop in the same distance.
Example: A vehicle carrying a load of 14,000 kg down a grade at 16 km/h is brought to a stop in a distance of 30 metres by normal brake application. If the same vehicle carried 28,000 kg down the same grade at 32 km/h, it would require eight times the braking power to stop the vehicle in 30 metres. This would be more braking power than the brakes could provide. No vehicle has enough braking power when it exceeds its limitations.
It's not just the stopping power that's important, it's how it can handle heat. The standard cooper 7.5" discs will very comfortably stop a mini from 160kph. Even the old drums on my 998 would very effectively stop from 100kph. But once you do it two, three times in a row, things will very quickly start to fade, and then fail.
8.4" discs with good pads will stop any mini from any speed they can reach. But if the brakes are going to go onto the track or see any amount of consistent, heavy braking, you'll want to move up to ventilated brakes. I've never heard anyone say that their ventilated 8.4" brakes were not up to the job.