centurion
Well-Known Member
Seen a spate of brake upgrade post recently. After having the fortune to hang around with engineers like my dad and some I met on this board, and a ravenous appetite I have to read everything about cars, and spending my own money on brakes on my previous cars and one of my current cars, let me share some observations.
1) Upgrade brakes rarely feel as good as stock - OEMs spend a lot of time tuning the brake subsystem for good balance in smoothness, stopping performance, safety, feel, modulation ... the smoothness, feel and modulation part affects the way we feel the brakes as we press the stop pedal. A lot of it gotta do with matching the master brake cylinder with the caliper piston size, and tuning the electronic brake distribution parameters to match the parameters of the front and rear brake system. If your brakes have too many pistons or too big pistons for your master brake cylinder, you will lose modulation and feel. The car will like STOP suddenly or don't stop. 1 or 0 binary behaviour.
2) Upgrade brakes do not necessarily brake shorter distance as stock if the brakes are not overheated - in normal highway driving, even NSH driving, you rarely overheat the brakes if you don't do extremely spirited accelerate-brake sequences like 20 times in 5 minutes. If you are the type who drives below 170km/h you need to brake slightly at most once every 5 minutes. When you brake hard enough, the caliper sure as hell can grab your rotor hard enough to lock your brakes and tyres - you can always invoke ABS on your stock brakes, right? Stopping distance of a car is directly proportional to tyre friction, NOT the size of your brakes. What's worse for the case of upgraded brakes, is that your electronic brake force distribution system in every performance car, may not be tuned to your big new brakes. EBD does a lot to decrease braking distances by feeding brakeforce to the rear once the front traction is finished. But it works within parameters, anytime it is out of parameter it will revert to limp mode behaviour. Meaning, longer brake distances. An example is the installation of the intensely rear biased GT3 braking system to a 987-series car with a mid engine. The rear will lock almost immediately on hard braking and the EBD will not respond properly, despite heroic efforts this can't be remedied.
3) Upgrade brakes are good for consistency under extreme stress - if you go to track, a BBK will be better than stock, simply because if you do lap after lap the bigger brakes can soak more heat and prevent your brake fluid from boiling so quickly. If you go to track upgrade brakes AND pads are definitely a consideration.
4) You lose the brakewear sensor with upgrade brakes - if you use upgrade brakes it is almost definite that you lose the brake pad wear sensor. Which is OK if you are the type who checks the damn thing every day, but if you're note, one day you will just experience the ugly screech of metal to metal interface destroying your rotors.
5) Insurance issues - if one has a bad accident, with huge claims, with brake failure being a factor, insurance companies pull out all stops.
6) Replacement costs - I don't kid myself. Even on my untrackable car, I would need a rotor change every 1.5 to 2 years for comfortable braking. Basically a rotor change every time I change a pad. Stock rotors are not breathtakingly expensive, but most BBKs are. Unless you can change to a BBK from a higher version of your car (eg. using 335 brakes on a 320) non-OE parts are always more expensive than OE parts. For both rotors and pads. Recently the aftermarket BBK rotor on my MPV cost 2X the price of the stock brake rotor of a Porsche.
7) Strange tyre and pad wear patterns - this is about EBD again. If you have too much mechanical front brake bias, most of the car stopping is done by the front pads. Depending on the way your EBD is tuned, it will also usually bias the front brakes to the front, electronically (so you don't spin the car). There are cases of people who upgraded the front brakes, that the rear brakes do not get used AT ALL. It's always the front taking the load, and tyre and pad wear, also rotors, on the front gets stupid high, and the rear tyres don't get used at all, especially in a all-street driving scenario.
So, before you go out to get that sexy bbk, this is my contribution to keeping money in your pocket, and perhaps, to increase safety.
The reason why I dunked money on a BBK on my MPV bigger than my performance car, is because the MPV does mainly long distance driving and hillclimbs (my son's favourite destination is on a hill). I warped 2 sets of stock rotors in 6 months on the fronts before I needed to take the BBK on. The reason for warpage was because the brakes were definitely underspec-ed for a MPV going at 180-200km/h - I could not even sustain more than 2 hard brakes every 5 minutes before heat above the design parameters of the stock rotor will cause uneven rotor expansion will start to judder the front brakes.
1) Upgrade brakes rarely feel as good as stock - OEMs spend a lot of time tuning the brake subsystem for good balance in smoothness, stopping performance, safety, feel, modulation ... the smoothness, feel and modulation part affects the way we feel the brakes as we press the stop pedal. A lot of it gotta do with matching the master brake cylinder with the caliper piston size, and tuning the electronic brake distribution parameters to match the parameters of the front and rear brake system. If your brakes have too many pistons or too big pistons for your master brake cylinder, you will lose modulation and feel. The car will like STOP suddenly or don't stop. 1 or 0 binary behaviour.
2) Upgrade brakes do not necessarily brake shorter distance as stock if the brakes are not overheated - in normal highway driving, even NSH driving, you rarely overheat the brakes if you don't do extremely spirited accelerate-brake sequences like 20 times in 5 minutes. If you are the type who drives below 170km/h you need to brake slightly at most once every 5 minutes. When you brake hard enough, the caliper sure as hell can grab your rotor hard enough to lock your brakes and tyres - you can always invoke ABS on your stock brakes, right? Stopping distance of a car is directly proportional to tyre friction, NOT the size of your brakes. What's worse for the case of upgraded brakes, is that your electronic brake force distribution system in every performance car, may not be tuned to your big new brakes. EBD does a lot to decrease braking distances by feeding brakeforce to the rear once the front traction is finished. But it works within parameters, anytime it is out of parameter it will revert to limp mode behaviour. Meaning, longer brake distances. An example is the installation of the intensely rear biased GT3 braking system to a 987-series car with a mid engine. The rear will lock almost immediately on hard braking and the EBD will not respond properly, despite heroic efforts this can't be remedied.
3) Upgrade brakes are good for consistency under extreme stress - if you go to track, a BBK will be better than stock, simply because if you do lap after lap the bigger brakes can soak more heat and prevent your brake fluid from boiling so quickly. If you go to track upgrade brakes AND pads are definitely a consideration.
4) You lose the brakewear sensor with upgrade brakes - if you use upgrade brakes it is almost definite that you lose the brake pad wear sensor. Which is OK if you are the type who checks the damn thing every day, but if you're note, one day you will just experience the ugly screech of metal to metal interface destroying your rotors.
5) Insurance issues - if one has a bad accident, with huge claims, with brake failure being a factor, insurance companies pull out all stops.
6) Replacement costs - I don't kid myself. Even on my untrackable car, I would need a rotor change every 1.5 to 2 years for comfortable braking. Basically a rotor change every time I change a pad. Stock rotors are not breathtakingly expensive, but most BBKs are. Unless you can change to a BBK from a higher version of your car (eg. using 335 brakes on a 320) non-OE parts are always more expensive than OE parts. For both rotors and pads. Recently the aftermarket BBK rotor on my MPV cost 2X the price of the stock brake rotor of a Porsche.
7) Strange tyre and pad wear patterns - this is about EBD again. If you have too much mechanical front brake bias, most of the car stopping is done by the front pads. Depending on the way your EBD is tuned, it will also usually bias the front brakes to the front, electronically (so you don't spin the car). There are cases of people who upgraded the front brakes, that the rear brakes do not get used AT ALL. It's always the front taking the load, and tyre and pad wear, also rotors, on the front gets stupid high, and the rear tyres don't get used at all, especially in a all-street driving scenario.
So, before you go out to get that sexy bbk, this is my contribution to keeping money in your pocket, and perhaps, to increase safety.
The reason why I dunked money on a BBK on my MPV bigger than my performance car, is because the MPV does mainly long distance driving and hillclimbs (my son's favourite destination is on a hill). I warped 2 sets of stock rotors in 6 months on the fronts before I needed to take the BBK on. The reason for warpage was because the brakes were definitely underspec-ed for a MPV going at 180-200km/h - I could not even sustain more than 2 hard brakes every 5 minutes before heat above the design parameters of the stock rotor will cause uneven rotor expansion will start to judder the front brakes.
