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      09-03-2013, 08:50 PM   #1
dazzabb
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Actual stopping distance data for BBK

I'm sure this has been asked before, but I couldnt find the answer after searching...I realise it wont be an easy question to answer.

I'm looking at a front upgrade kit, either BBK, or PFD discs and new pads etc.

But if possible I would like to see some actual factual data on improved stopping distances after brake upgrades.

There is a mass of info on "perceived" improvements but wondering if anybody has actually measured it or compared different makes etc.

This is purely for road use with PSS tyres.
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      09-03-2013, 09:01 PM   #2
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Well if you had over to the track forums, everyone agrees that bbk is mainly for much more thermal capacity. Pads and tires are the only thing that really effects braking distance.
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      09-03-2013, 09:04 PM   #3
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Different on a track w/ heat issues obviously, but there were a couple of automotive rag road tests of the M5 and M6 w/ carbon ceramic break option that actually had longer stopping distances vs stock (and unbelievably the M6 CC breaks were exhibiting significant fade).
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      09-03-2013, 11:55 PM   #4
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Quote:
Originally Posted by eternallx View Post
Well if you had over to the track forums, everyone agrees that bbk is mainly for much more thermal capacity. Pads and tires are the only thing that really effects braking distance.
+1

Even if there were tests as such, I'd be skeptical about getting any type of statically meaningful results because there are so many variables at play - the road surface, tires, brakes, pads, driver, etc.
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      09-04-2013, 10:31 AM   #5
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It's about the heat management and decreased unsprung weight. Stopping distances over a few hard stops don't really matter on a hot lap.
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      09-04-2013, 01:01 PM   #6
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Quote:
Originally Posted by eternallx View Post
Well if you had over to the track forums, everyone agrees that bbk is mainly for much more thermal capacity. Pads and tires are the only thing that really effects braking distance.
Quote:
Originally Posted by Transfer View Post
It's about the heat management and decreased unsprung weight. Stopping distances over a few hard stops don't really matter on a hot lap.
These quotes say it all. If you are looking for a BBK only for streat use, they are way overkill but look very nice!!
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      09-04-2013, 01:48 PM   #7
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Over the years, I have read articles in car magazines testing "big brake kits" on other cars. Generally for one stop from 60 mph or 80 mph, there is little to no difference. There may be a small difference from 100 mph or 120 mph or 150 mph. The reality is that the stock brakes on a performance car like the M3 are good enough for just about any emergency stop.

Similar articles have shown small gains from just adding performance pads. This is for street use, where just one stop is measured.

As the stops are repeated one after the other, with little to no cool down time (other than the time to return to the beginning of the test place and then to accelerate back up to speed), the benefits from performance pads or big brakes begins to appear. On a track, the benefits can definitely be noticed and measured. Ten stops in a row, and the performance pads or big brakes show consistent repeatable results while the stock brakes' distances grow and grow

On the street, you would have to drive like a crazy person to get really significant benefit. For most people driving on the street, just higher performance pads would be enough.

The problem with higher performance pads is that they move the entire heat range upwards. This means the pads are not as good as stock on the initial bite. They need a little heat and then they work better than stock. This is true of all performance pads. There is no pad that is both better cold and better hot.

So just changing pads gives some gains once you get the brakes hot enough to exceed the range of the stock pads. One advantage of bigger brakes is that they and absorb and dissipate more heat, which means you could run a stock-like compound pad and still have more range before heat related fade appears.

If your brakes are fading because you are getting them so hot they are boiling the fluid, you can gain some benefit by changing to a higher performance fluid.

I do not have big brakes on either of my M3s, although I do have performance pads and newer braided brake hoses and performance fluid. I do not track either car and have never faded the brakes. Maybe if I did a lot of dangerously high speed mountain or canyon driving, I could fade them on the street, but there are no canyons where I live. There are mountains, but if I can't see who might be coming up when I am going down, I won't drive fast enough to fade them. I have done many 140 to 60 stops and many 120 to 30 stops and never faded, but have always had some time before the next such stop, so the heat dissipated.

My view is that, for most people, big brakes for the street are unnecessary.
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      09-04-2013, 08:07 PM   #8
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I think the tires have the greatest overall effect on stopping distances. Any brake setup can bring you to anti-lock threshold if you stomp on them.

The main reason for a BBK on the track is, as has been said, is thermal capacity, so as to get REPEATABLE stopping distances hot lap after hot lap, without fade.
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      09-05-2013, 04:51 AM   #9
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Quote:
Originally Posted by pbonsalb View Post
Over the years, I have read articles in car magazines testing "big brake kits" on other cars. Generally for one stop from 60 mph or 80 mph, there is little to no difference. There may be a small difference from 100 mph or 120 mph or 150 mph. The reality is that the stock brakes on a performance car like the M3 are good enough for just about any emergency stop.

Similar articles have shown small gains from just adding performance pads. This is for street use, where just one stop is measured.

As the stops are repeated one after the other, with little to no cool down time (other than the time to return to the beginning of the test place and then to accelerate back up to speed), the benefits from performance pads or big brakes begins to appear. On a track, the benefits can definitely be noticed and measured. Ten stops in a row, and the performance pads or big brakes show consistent repeatable results while the stock brakes' distances grow and grow

On the street, you would have to drive like a crazy person to get really significant benefit. For most people driving on the street, just higher performance pads would be enough.

The problem with higher performance pads is that they move the entire heat range upwards. This means the pads are not as good as stock on the initial bite. They need a little heat and then they work better than stock. This is true of all performance pads. There is no pad that is both better cold and better hot.

So just changing pads gives some gains once you get the brakes hot enough to exceed the range of the stock pads. One advantage of bigger brakes is that they and absorb and dissipate more heat, which means you could run a stock-like compound pad and still have more range before heat related fade appears.

If your brakes are fading because you are getting them so hot they are boiling the fluid, you can gain some benefit by changing to a higher performance fluid.

I do not have big brakes on either of my M3s, although I do have performance pads and newer braided brake hoses and performance fluid. I do not track either car and have never faded the brakes. Maybe if I did a lot of dangerously high speed mountain or canyon driving, I could fade them on the street, but there are no canyons where I live. There are mountains, but if I can't see who might be coming up when I am going down, I won't drive fast enough to fade them. I have done many 140 to 60 stops and many 120 to 30 stops and never faded, but have always had some time before the next such stop, so the heat dissipated.

My view is that, for most people, big brakes for the street are unnecessary.
Thanks for such a detailed reply.

My brakes have not yet failed to stop me either but there have been occassions when I thought they might not....
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      09-05-2013, 06:23 PM   #10
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Quote:
Originally Posted by Sleeper519 View Post
I think the tires have the greatest overall effect on stopping distances. Any brake setup can bring you to anti-lock threshold if you stomp on them.

The main reason for a BBK on the track is, as has been said, is thermal capacity, so as to get REPEATABLE stopping distances hot lap after hot lap, without fade.
+1...fully agree but I will add something. A BBK provides a significant handling improvement under threshold and trail braking. Its almost like a revelation! With the OEM brakes the rear end would wiggle and the car would not be very stable. Not to mention the on/off feel..at least that's my opinion.

On the street, you will never threshold or trail brake so you won't notice this benefit...which is a HUGE benefit for the track.
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      09-05-2013, 09:09 PM   #11
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Quote:
Originally Posted by bigjae1976 View Post
+1...fully agree but I will add something. A BBK provides a significant handling improvement under threshold and trail braking. Its almost like a revelation! With the OEM brakes the rear end would wiggle and the car would not be very stable. Not to mention the on/off feel..at least that's my opinion.

On the street, you will never threshold or trail brake so you won't notice this benefit...which is a HUGE benefit for the track.

Agree. +1 for added control and feel.
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      09-06-2013, 01:50 AM   #12
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Better stopping distance for safety on the street is just the excuse you use to convince your significant other that you need them on your car.
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      09-09-2013, 02:44 PM   #13
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Quote:
Originally Posted by dazzabb View Post
I'm sure this has been asked before, but I couldnt find the answer after searching...I realise it wont be an easy question to answer.

I'm looking at a front upgrade kit, either BBK, or PFD discs and new pads etc.

But if possible I would like to see some actual factual data on improved stopping distances after brake upgrades.

There is a mass of info on "perceived" improvements but wondering if anybody has actually measured it or compared different makes etc.

This is purely for road use with PSS tyres.
I can't give you any measurements now but I've attended numerous skills days with the IAM (UK advanced driving group) where stopping distances have been measured and BBKs make no difference at all. Stock brakes are more than capable of locking the wheels under braking, a BBK more so. The limiting factor is the tyre.

For the track, heat build up is a problem, and BBKs can help to dissipate heat better, reducing brake fade but a change in pads and high-boiling point brake fluid can produce similar results.
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      09-09-2013, 07:34 PM   #14
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Quote:
Originally Posted by radiantm3
Better stopping distance for safety on the street is just the excuse you use to convince your significant other that you need them on your car.
Haha definitely going to be remembering that one! Interesting thread thanks for the question and replies!
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      09-11-2013, 05:03 AM   #15
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Well you've all done a great job persuading me to stick with standard and save a few grand. Cheers!
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      09-24-2013, 05:26 PM   #16
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Quote:
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Better stopping distance for safety on the street is just the excuse you use to convince your significant other that you need them on your car.
Sad to say...but he is right. This worked for me.

And boy, are they pretty!!!
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