The difference between overservoed and good brakes
Discussion
I've been trying to explain to a few VAG drivers I know that, just because their car stops sharply it doesn't mean it has amazing brakes - it just means they have the usual VAG over-assistance.
However, I must admit that, obviously, a car with very powerful brakes (ie. big discs and soft pads) would also do the same. So, how would one explain the difference in feel to the driver between the two? Would it be centred mainly on he amount of feedback in the pedal?
However, I must admit that, obviously, a car with very powerful brakes (ie. big discs and soft pads) would also do the same. So, how would one explain the difference in feel to the driver between the two? Would it be centred mainly on he amount of feedback in the pedal?
ChemicalChaos said:
I've been trying to explain to a few VAG drivers I know that, just because their car stops sharply it doesn't mean it has amazing brakes - it just means they have the usual VAG over-assistance.
However, I must admit that, obviously, a car with very powerful brakes (ie. big discs and soft pads) would also do the same. So, how would one explain the difference in feel to the driver between the two? Would it be centred mainly on he amount of feedback in the pedal?
Does it really matter? As long as they stop with a good amount of feel that's what matters. Some cars with huge discs have terrible feel - e.g. the new E63 AMGHowever, I must admit that, obviously, a car with very powerful brakes (ie. big discs and soft pads) would also do the same. So, how would one explain the difference in feel to the driver between the two? Would it be centred mainly on he amount of feedback in the pedal?
Good brakes have a linearity to them, a little bit of pedal gives a little bit of braking effort, a lot of pedal gives a lot of braking effort. VAG brakes give you a little bit of pedal and nearly all of the braking ability they've got to give. It makes them feel strong and "sporty" to people who don't know what good brakes feel like, but the truth is that there is little depth to their ability, you use a lot their braking effort every day due to the servo setup, but when you try to ask for a lot more braking ability you find they've not got a lot more to give.
t when I got it, granted they were but still a few uh oh moments lol thinking its not going to stop untill I applied a little more.Over assisted brakes vs nicely assisted ones is very much like comparing an NA petrol engines power delivery with that of a turbodiesel.
Both might have the same peak power available, but one gets faster the harder you push it, the other is pretty much giving everything it's got just trundling around at low RPM and doesn't get any better the harder you push it.
Both might have the same peak power available, but one gets faster the harder you push it, the other is pretty much giving everything it's got just trundling around at low RPM and doesn't get any better the harder you push it.
Mave said:
Its about linearity.
Good brakes - light pressure = light braking. medium pressure = medium braking. heavy pressure = heavy braking.
VAG brakes - light pressure = medium braking. medium pressure = medium braking. heavy pressure = medium braking.
Good brakes - light pressure = light braking. medium pressure = medium braking. heavy pressure = heavy braking.
VAG brakes - light pressure = medium braking. medium pressure = medium braking. heavy pressure = medium braking.
The worst car I've ever experienced for this is a Hyundai Pony X2. Even looking at the brake pedal locked the front wheels at any speed. I honestly couldn't drive it safely because the brakes were so light.
I drive a VW and while the brakes are very sharp they are by no means bad. The servo is just a mechanical force amplifier and it is calibrated such that maximum brake pressure sufficient to activate the ABS on dry tarmac can be applied by any driver in an emergency. Once you get the hang of the systems gain then you just modulate your foot pressure accordingly.
What I really don't like is pedals which are extremely sharp in their operation but have a deadzone at the top where there is little resistance and no braking effect. That is hard to modulate because you get nothing, nothing , EMERGENCY STOP! as opposed to a linear response with a fixed gain.
What I really don't like is pedals which are extremely sharp in their operation but have a deadzone at the top where there is little resistance and no braking effect. That is hard to modulate because you get nothing, nothing , EMERGENCY STOP! as opposed to a linear response with a fixed gain.
Swapping from the Octavia (typical stupid VAG configuration, with an inch of dead travel then 100% braking force a fraction lower down) to the Elise (completely unassisted, no dead travel at all) is certainly challenge.
I'd have to have a very good reason to go back to assisted brakes in a sports car; I've never driven a setup that feels anywhere near as nice as a good unassisted set. You do have to apply a fair amount of force to stop the Elise quickly from high speed though. It's a significant amount of effort to lock the wheels at 100mph.
I'd have to have a very good reason to go back to assisted brakes in a sports car; I've never driven a setup that feels anywhere near as nice as a good unassisted set. You do have to apply a fair amount of force to stop the Elise quickly from high speed though. It's a significant amount of effort to lock the wheels at 100mph.
Edited by kambites on Friday 11th April 12:47
Hooli said:
The worst car I've ever experienced for this is a Hyundai Pony X2. Even looking at the brake pedal locked the front wheels at any speed. I honestly couldn't drive it safely because the brakes were so light.
kambites said:
I'd have to have a very good reason to go back to assisted brakes in a sports car; I've never driven a setup that feels anywhere near as nice as a good unassisted set. You do have to apply a fair amount of force to stop the Elise quickly from high speed though.
newer Elises have servos, but they're a long way from VAG brakes and will no doubt still surprise new drivers coming out of a eurobox. Edited by kambites on Friday 11th April 12:47
Similarly Lotus traction control is a great lesson on how it should be done. In conjunction with Bosch they've developed something that let's the driver control the car and not over-nanny everything. All this before we even get to suspension set-up...
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