The beasts are fitted.....some crap pics page 15
- Thread starter ncrossy1980
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Nice 8)
sars said:
I'd not realised that a BBK needs formal certification of its ability to kill before it may be sold :? :wink:
:lol:My money is with the "over-braked at the rear" opinion rather than the "trust the manufacturer as surely they will have made a few informed calculations" brigade, but I am a cynic! Of course, it may not be an issue with normal day to day driving, but I suspect it would be under high duress on a track.
Jonny, they are going to look great on your car and well done for doing the work yourself. Take it easy until you're familiar with the new characteristics of your braking system!
sars said:I love reading this stuff and comments made by would be engineers, I get them all day at work and whilst it sometimes gets frustrating with some really interesting questions (and for the record there are no such thing as a stupid question) I try and answer/educate when ever I can.
But seriously guys, Jonny has gone to a professional outfit, told them what he has and they have given him what they believe, in their professional opinion, what he needs. It's not like he's (jonny) gone down to the pub and picked up some dodgy brake parts from bodget and scarper and you're wondering if the master cylinder is big enough
So get real, we are talking brakes, do you honestly believe a professional outfit, an American manufacturer with TUV ISO 9001 certification, would supply an aftermarket kit that could possibly kill someone without making sure it is fit for purpose.
What a ridiculous thing to say! Jonny has gone to a professional outfit yes - a brake supplier. Someone who wants to sell brakes. "Yes sir, they fit your car". I would imagine the brake components will be warrantied against any mechanical defects, but I highly doubt there would be come-back once they are fitted - particularly if it is a set-up issue. "Oh your car is braking too much at the rear? The brakes are working then - fit a bias valve" will be the response - I'd put money on it. Furthermore there is absolutely no legal or documented evidence to prove categorically that D2 "explicitly confirm that these calipers will work in perfect harmony on Jonny Essex's 2.0 E85 Z4 with the red roof etc.etc.etc.)."
They have told Jonny that the calipers fit and work. They will. It will naturally fall to Jonny himself, or to the unfortunate company lumbered with fitting them and setting them up for Jonny to fit a bias valve to get the brake bias to a usable balance front/rear - let alone back to OEM balance.
It is extremely likely the company will be used to dealing mostly with people who are tracking their cars and have reached the limits of their OEM brake set-up. These people will be resonably clued up on brake balance, and cruicially prepared to do their homework, and fiddle to get the best out of the set-up. Not just bung them on and hope for the best....
I'm afraid I don't care what anyone has told Jonny to date, I'll state now for the record; those brakes once fitted are going to cause the rear of the car to be massively over-braked - in my opinion to a quite alarming, and potentially dangerous degree - without a bias valve and someone who knows what they're doing to set it up.
Sorry Jonny, I've done my level best to refrain from commenting anything non-constructive, but I feel from a safety perspective it needs to be said... I will keep my personal opinion regarding the necessity of the brake upgrade to myself, as it's your car and your money, and doing what you want with the car is entirely your perogative.
Needless to say I do think, in the main your car is a lovely example and clearly very well cared for - and I look forward at some point to having a look over it in the metal Ed Doe said:sars said:I love reading this stuff and comments made by would be engineers, I get them all day at work and whilst it sometimes gets frustrating with some really interesting questions (and for the record there are no such thing as a stupid question) I try and answer/educate when ever I can.
But seriously guys, Jonny has gone to a professional outfit, told them what he has and they have given him what they believe, in their professional opinion, what he needs. It's not like he's (jonny) gone down to the pub and picked up some dodgy brake parts from bodget and scarper and you're wondering if the master cylinder is big enough
So get real, we are talking brakes, do you honestly believe a professional outfit, an American manufacturer with TUV ISO 9001 certification, would supply an aftermarket kit that could possibly kill someone without making sure it is fit for purpose.
What a ridiculous thing to say! Jonny has gone to a professional outfit yes - a brake supplier. Someone who wants to sell brakes. "Yes sir, they fit your car". I would imagine the brake components will be warrantied against any mechanical defects, but I highly doubt there would be come-back once they are fitted - particularly if it is a set-up issue. "Oh your car is braking too much at the rear? The brakes are working then - fit a bias valve" will be the response - I'd put money on it. Furthermore there is absolutely no legal or documented evidence to prove categorically that D2 "explicitly confirm that these calipers will work in perfect harmony on Jonny Essex's 2.0 E85 Z4 with the red roof etc.etc.etc.)."
They have told Jonny that the calipers fit and work. They will. It will naturally fall to Jonny himself, or to the unfortunate company lumbered with fitting them and setting them up for Jonny to fit a bias valve to get the brake bias to a usable balance front/rear - let alone back to OEM balance.
It is extremely likely the company will be used to dealing mostly with people who are tracking their cars and have reached the limits of their OEM brake set-up. These people will be resonably clued up on brake balance, and cruicially prepared to do their homework, and fiddle to get the best out of the set-up. Not just bung them on and hope for the best....
I'm afraid I don't care what anyone has told Jonny to date, I'll state now for the record; those brakes once fitted are going to cause the rear of the car to be massively over-braked - in my opinion to a quite alarming, and potentially dangerous degree - without a bias valve and someone who knows what they're doing to set it up.
Sorry Jonny, I've done my level best to refrain from commenting anything non-constructive, but I feel from a safety perspective it needs to be said... I will keep my personal opinion regarding the necessity of the brake upgrade to myself, as it's your car and your money, and doing what you want with the car is entirely your perogative.
^^^^^^^^^^^^
Most sensible thing said all day..
And very accurate to boot....
By the seaside...
IAWTP, if you look at the suppliers it appears that, as long as they have a bracket fitment for your car, they will let you select any combination of front and rear sizes you want. There may be some but I haven't seen any sites that sell D2, K Sport etc. as a matched 4 wheel kit only as independent front and rear sets. If you want 380mm rears and 220mm fronts, they'll sell them to you. It's 'buyer beware' and if you choose to fit (or have fitted) mismatched front & rear sets to your car, it's your responsibility to ensure that your car will be safe.Ed Doe said:What a ridiculous thing to say! Jonny has gone to a professional outfit yes - a brake supplier. Someone who wants to sell brakes. "Yes sir, they fit your car". I would imagine the brake components will be warrantied against any mechanical defects, but I highly doubt there would be come-back once they are fitted - particularly if it is a set-up issue. "Oh your car is braking too much at the rear? The brakes are working then - fit a bias valve" will be the response - I'd put money on it. Furthermore there is absolutely no legal or documented evidence to prove categorically that D2 "explicitly confirm that these calipers will work in perfect harmony on Jonny Essex's 2.0 E85 Z4 with the red roof etc.etc.etc.)."sars said:I love reading this stuff and comments made by would be engineers, I get them all day at work and whilst it sometimes gets frustrating with some really interesting questions (and for the record there are no such thing as a stupid question) I try and answer/educate when ever I can.
But seriously guys, Jonny has gone to a professional outfit, told them what he has and they have given him what they believe, in their professional opinion, what he needs. It's not like he's (jonny) gone down to the pub and picked up some dodgy brake parts from bodget and scarper and you're wondering if the master cylinder is big enough
So get real, we are talking brakes, do you honestly believe a professional outfit, an American manufacturer with TUV ISO 9001 certification, would supply an aftermarket kit that could possibly kill someone without making sure it is fit for purpose.
They have told Jonny that the calipers fit and work. They will. It will naturally fall to Jonny himself, or to the unfortunate company lumbered with fitting them and setting them up for Jonny to fit a bias valve to get the brake bias to a usable balance front/rear - let alone back to OEM balance.
It is extremely likely the company will be used to dealing mostly with people who are tracking their cars and have reached the limits of their OEM brake set-up. These people will be resonably clued up on brake balance, and cruicially prepared to do their homework, and fiddle to get the best out of the set-up. Not just bung them on and hope for the best....
I'm afraid I don't care what anyone has told Jonny to date, I'll state now for the record; those brakes once fitted are going to cause the rear of the car to be massively over-braked - in my opinion to a quite alarming, and potentially dangerous degree - without a bias valve and someone who knows what they're doing to set it up.
welcome to the world of epic brakes jonny!! mine were actually lighter than the ///M setup on their beforehand, I've had these things glowing and still drove home without so much as a shimmy or vibration, they do however make loads of smoke which is alittle off-putting :| :| :| :| :| :| :|
Might be another stupid question but I take it there are carriers supplied with these calipers?
The mounting points are in different places from the standard calipers so would not be a direct fit without them.
Someone else asked about a pic of everything supplied, it would be good to see.
The mounting points are in different places from the standard calipers so would not be a direct fit without them.
Someone else asked about a pic of everything supplied, it would be good to see.
Sorry I thought you had said "the beasts" have arrived which meant the kit had arrived, must have missed the bit where you said you were still waiting on some of it.Jonny essex said:Like mentioned before there is a 2-5 week wait as they are made model specific so i assume the carriers that came with the kit are already fabricated to fit onto my car.Nictrix said:
I thought you said you were fitting them in 2 weeks.
Drastically moving the brake bias rearward will result in the rear wheels locking up before maximum braking force has been reached, which will inevitably result in a spin. Precisely the same as why you don't lock your front wheel on your mountain bike, but you likely frequently lock your rear - though there the similarities end, as you can alter the weight distribution to prevent the pendulum effect of locking the rear in a car.
It's dangerous when you're discovering how modifying brake bias affects braking for the first time on the public highway - and even more dangerous for not expecting and consequently being prepared for that discovery!!! It's also dangeroud that a bias valve has not been fitted such that a swift change in balance can be affected should there be any issues. Less on the danger front, but still pertinent is that long-term the fitment of a bias valve will permit tweaking of the balance to the optimum setting for Jonny's taste.
A rudimentary google-search to substantiate the above:
Maximum braking performance occurs just before brake lockup, as a sliding tire has less grip than a rolling tire, thus tuning brake balance is all about controlling when the brakes lockup. As max performance obviously will occur when all 4 tires (& associated brakes) are doing the maximum work, an ideal brake bias is one that locks the front and rear brakes at the same time. In practice however, locking the rear tires typically result in a rapid spin, and locking all 4 wheels results in a slower spin, especially if the car is trail braking. For this reason, some “extra” front bias is normally used, because when the front brakes lockup the car remains stable (but you lose the ability to steer the car – it just goes straight) and this allows the driver time to recognize the brake lockup and reduce brake pressure to regain max braking performance and control. To tune the brake bias, pay particular attention to what happens during the braking phase and corner entry. Sudden spins in this zone often indicate rear brake lockup, while a bad push may indicate front brake lockup.
Increasing Front bias: Increasing brake bias to the front will put more braking force into the front tires. This will stabilize the car in braking zones and increase understeer at corner entry. The compromise is that with too much front bias the rear tires are being under‐utilized and overall braking efficiency will suffer. This can also cause rapid front tire wear due to front tire lockup, especially of the inside tire which is the first to lock up.
Reducing Front bias: This puts more braking on the rear tires, which, within limits, improves braking efficiency. Too much rear brake bias, though, hurts performance in two ways. First, it reduces overall braking efficiency. More seriously, too much rear brake bias, particularly if the driver is not braking in a straight line or has weak footwork on downshifts, can cause the rear tires to lock up, which puts the car in a dynamically unstable condition that can easily result in loss of vehicle control. Note that with a moderate amount of rear‐brake bias, the car will have a tendency to rotate (OVERsteer) at corner entry upon brake release.
The danger is that from what I've read in the main project thread and the few others where a lengthy discussion has taken place, Jonny is not aware of the potential results of what will be quite a significant shift in brake bias; and quite what that entails.
It's dangerous when you're discovering how modifying brake bias affects braking for the first time on the public highway - and even more dangerous for not expecting and consequently being prepared for that discovery!!! It's also dangeroud that a bias valve has not been fitted such that a swift change in balance can be affected should there be any issues. Less on the danger front, but still pertinent is that long-term the fitment of a bias valve will permit tweaking of the balance to the optimum setting for Jonny's taste.
A rudimentary google-search to substantiate the above:
Maximum braking performance occurs just before brake lockup, as a sliding tire has less grip than a rolling tire, thus tuning brake balance is all about controlling when the brakes lockup. As max performance obviously will occur when all 4 tires (& associated brakes) are doing the maximum work, an ideal brake bias is one that locks the front and rear brakes at the same time. In practice however, locking the rear tires typically result in a rapid spin, and locking all 4 wheels results in a slower spin, especially if the car is trail braking. For this reason, some “extra” front bias is normally used, because when the front brakes lockup the car remains stable (but you lose the ability to steer the car – it just goes straight) and this allows the driver time to recognize the brake lockup and reduce brake pressure to regain max braking performance and control. To tune the brake bias, pay particular attention to what happens during the braking phase and corner entry. Sudden spins in this zone often indicate rear brake lockup, while a bad push may indicate front brake lockup.
Increasing Front bias: Increasing brake bias to the front will put more braking force into the front tires. This will stabilize the car in braking zones and increase understeer at corner entry. The compromise is that with too much front bias the rear tires are being under‐utilized and overall braking efficiency will suffer. This can also cause rapid front tire wear due to front tire lockup, especially of the inside tire which is the first to lock up.
Reducing Front bias: This puts more braking on the rear tires, which, within limits, improves braking efficiency. Too much rear brake bias, though, hurts performance in two ways. First, it reduces overall braking efficiency. More seriously, too much rear brake bias, particularly if the driver is not braking in a straight line or has weak footwork on downshifts, can cause the rear tires to lock up, which puts the car in a dynamically unstable condition that can easily result in loss of vehicle control. Note that with a moderate amount of rear‐brake bias, the car will have a tendency to rotate (OVERsteer) at corner entry upon brake release.
The danger is that from what I've read in the main project thread and the few others where a lengthy discussion has taken place, Jonny is not aware of the potential results of what will be quite a significant shift in brake bias; and quite what that entails.
:lol: 
As I've mentioned before, the brakes don't stop the car, the tyres do!
Each tyre has a maximum amount of braking force that can be applied through it's contact patch, this is dictated by the weight over the tyre and the coefficient of friction of the rubber, if you exceed that amount the wheel will lock and the tyre will slide. Assuming identical tyres all round, in a car like the Z4 the front tyres are capable of generating greater breaking forces than the rears because you have the weight of the engine over the front axle plus the additional weight transfer forward during the braking process, this is why you tend to have bigger brakes on the front - bigger rotors are capable of applying more ft lbs of torque.
The art with brakes is to balance the system so that all tyres are exerting roughly the same percentage of their maximum braking force when you hit the pedal - this doesn't mean that the amount of retardation at each wheel is the same just that when the fronts are at 25/50/100% of maximum retardation so are the rears. If you don't do this correctly you could end up with a situation where one set of tyres is locking up whilst the other set is comfortably within it's limits - best case is longer stopping distances (not what you expect from bigger brakes), worst case is loss of control and potentially ending up in a hedge/wall/ditch...
With virtually any modern set of OEM disk brakes the braking forces that can be generated by the standard setup is more than enough to overcome the braking forces that can be generated by the (road) tyres - hence the ubiquitous presence of ABS systems. Big Brake Kits are not there to make you stop faster, they can't as the limiting factor is the tyres - they might give you a bit more control, they should definitely fade less with repeated hard use on the track and they might make a certain sort of girl think you've got a really 'cool' car but, in normal road use, they won't/can't stop you any faster than the OEM brakes.
Each tyre has a maximum amount of braking force that can be applied through it's contact patch, this is dictated by the weight over the tyre and the coefficient of friction of the rubber, if you exceed that amount the wheel will lock and the tyre will slide. Assuming identical tyres all round, in a car like the Z4 the front tyres are capable of generating greater breaking forces than the rears because you have the weight of the engine over the front axle plus the additional weight transfer forward during the braking process, this is why you tend to have bigger brakes on the front - bigger rotors are capable of applying more ft lbs of torque.
The art with brakes is to balance the system so that all tyres are exerting roughly the same percentage of their maximum braking force when you hit the pedal - this doesn't mean that the amount of retardation at each wheel is the same just that when the fronts are at 25/50/100% of maximum retardation so are the rears. If you don't do this correctly you could end up with a situation where one set of tyres is locking up whilst the other set is comfortably within it's limits - best case is longer stopping distances (not what you expect from bigger brakes), worst case is loss of control and potentially ending up in a hedge/wall/ditch...
With virtually any modern set of OEM disk brakes the braking forces that can be generated by the standard setup is more than enough to overcome the braking forces that can be generated by the (road) tyres - hence the ubiquitous presence of ABS systems. Big Brake Kits are not there to make you stop faster, they can't as the limiting factor is the tyres - they might give you a bit more control, they should definitely fade less with repeated hard use on the track and they might make a certain sort of girl think you've got a really 'cool' car but, in normal road use, they won't/can't stop you any faster than the OEM brakes.