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Old 26-01-2011, 10:50 AM   #41
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Originally Posted by _Nathan_ View Post
Also - the suspension you have and it's effect on weight transfer under braking may change the optimum bias for your car...

Then you get in to other complexities like tyres and the weather, eg you move the bias rearwards when it is wet.

Basically on a car without bias adjustment is all you are looking for a compromise that suits you and your car's setup and driving style and maybe what is good for one isn't for another...
Nathan

That didnt help at all
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Old 26-01-2011, 10:52 AM   #42
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Old 26-01-2011, 11:38 AM   #43
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Can you show your calculations please.
I will tomorrow, can't be bothered now ... it's nearly mid night here and I am watching a movie with the mrs

I used CoF at 0.36 and 750psi braking pressure for the calculations.

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Originally Posted by _Nathan_ View Post
Also - the suspension you have and it's effect on weight transfer under braking may change the optimum bias for your car...

Then you get in to other complexities like tyres and the weather, eg you move the bias rearwards when it is wet.

Basically on a car without bias adjustment is all you are looking for a compromise that suits you and your car's setup and driving style and maybe what is good for one isn't for another...
Actually you could go on and argue that you need different brake bias for different sort of corners (as they do in F1).

But you are right, without a bias adjuster you will not have optimal braking for every single corner around the track.

Brake feel however is completely subjective.


Shimmy, I don't have any reference as to what is considered optimal braking. I've simply stated what the 'stock' is set at by BMW. Interesting they shifted the bias rearwards though in the CSL compared to the standard M3. Must have been a reason for doing that.
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Old 26-01-2011, 11:56 AM   #44
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I wonder if the weight saving on CSL mainly towards the rear meant they reduced rear bias?
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Old 26-01-2011, 12:01 PM   #45
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Old 26-01-2011, 07:24 PM   #46
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Quote:
Originally Posted by NZ_M3 View Post
This is incorrect if you do the math.

The Alcon is the only aftermarket brake kit out there that I know of that more or less retains the CSL brake bias out of the box. I did the math and it adds up.

See below.




Standard setup with an equivalent brake pad compound as the front Alcons. I am running pagid rs29 on the front alcons and performance friction pfc01 and the brake balance is "perfect" (quote from a veteran champion professional racing driver and acredited bmw driver training instructor who took my car for a test run around a new track yesterday and provided me with some setup feedback)


If you want me to get really technical I can ... but as a reference.

The stock E46 M3 has a front to rear brake bias ratio of 1.98 (i.e. front heavy)
The standard CSL has a front to rear brake bias ratio of 1.73 (i.e. shifted slightly to the rear compared to the stock M3)
The standard Alcon kit in both front and rear configuration has a front to rear brake bias ratio of 1.78 (i.e very close to the stock CSL setup)
Running just the front Alcon kit and retaining the stock CSL rear setup gives a front to rear brake bias ratio of 1.82 (so in between the stock M3 and CSL setup - which I've found to be much much better).

As for those going with the AP racing kit - those kit are actually WAY MORE rear biased compared to all the other kits out there. For e.g. the 5570 kit has a front to rear brake bias ratio of 1.61 (very rearward biased).

thank you very informative
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Old 26-01-2011, 09:03 PM   #47
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Nathan

That didnt help at all
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Old 26-01-2011, 09:34 PM   #48
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Quote:
Originally Posted by NZ_M3 View Post
This is incorrect if you do the math.

The Alcon is the only aftermarket brake kit out there that I know of that more or less retains the CSL brake bias out of the box. I did the math and it adds up.

See below.




Standard setup with an equivalent brake pad compound as the front Alcons. I am running pagid rs29 on the front alcons and performance friction pfc01 and the brake balance is "perfect" (quote from a veteran champion professional racing driver and acredited bmw driver training instructor who took my car for a test run around a new track yesterday and provided me with some setup feedback)


If you want me to get really technical I can ... but as a reference.

The stock E46 M3 has a front to rear brake bias ratio of 1.98 (i.e. front heavy)
The standard CSL has a front to rear brake bias ratio of 1.73 (i.e. shifted slightly to the rear compared to the stock M3)
The standard Alcon kit in both front and rear configuration has a front to rear brake bias ratio of 1.78 (i.e very close to the stock CSL setup)
Running just the front Alcon kit and retaining the stock CSL rear setup gives a front to rear brake bias ratio of 1.82 (so in between the stock M3 and CSL setup - which I've found to be much much better).

As for those going with the AP racing kit - those kit are actually WAY MORE rear biased compared to all the other kits out there. For e.g. the 5570 kit has a front to rear brake bias ratio of 1.61 (very rearward biased).

I appreciate your input Tom, but math aside, when I fitted the Alcons, driving the same track, same weather, same wheels/tyres,same suspension.

It affected the balance of the car under extreme braking, not alarmingly so, but enough for me to notice, and enough to see drops in corner entry/mid corner/corner exit speeds, which also slowed down my straight line speed.

The alcon kit is very very good, but just makes the car feel unbalanced at 100% attack.

I am also not the only person to notice this.

The "issue" obviously has not bothered me at all as I now have Alcon fitted on my Evo X.
brakes.jpg

A shameless Matt moment
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Old 26-01-2011, 10:21 PM   #49
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Attachment 3639

A shameless Matt moment
You WHORE!
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Old 26-01-2011, 10:26 PM   #50
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cheap as chips those itchy mingy alcons
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