baghall wrote:Thanks for the links guys have put myself down as interested in T4 rear discs. Find it interesting psimitar that the fronts in the later model could be worse than the earlier models.
Not necessarily worse in terms of day to day ability but in terms of outright performance they're mediocre.
The single piston sliding caliper is given a much larger piston diameter so that it has similar clamping force to the twin piston earlier caliper. Then they increase pad surface area to increase the amount of friction available but compared to a multiple piston caliper the sliding caliper can never compete just due to how the clamping force is spread across the pad.
In multi piston calipers the braking pressure is more evenly distributed over the pad leading to better brake feel and more even pressure onto the disc surface. The more evenly the pad is pressed against the disc then the larger area of friction compared to a single piston that will have reduced pad to disc pressure towards the edges of the pad. A 5mm steel back plate may seem quite thick but under such pressures you'd be surprised how much flex there is.
It's kinda funny how people don't realise how costs are being cut in high end performance vehicles like the sporty Mercs, Audis and Jags. They use discs the size of dustbin lids but use the cheap to manufacture single piston caliper compared to 5 or more years ago when they still used 4 pot calipers with smaller discs that could still out perform the larger latest single pot brakes
🙂
