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      11-06-2012, 11:17 AM   #67
uberschnell
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Quote:
Originally Posted by GaryS View Post
Well, I agree with most of that with some small quibbles.

Resistance to fade depends mostly on the choice of pads. Better ducting can help some, and better rotor design can help a little.

Heavier rotors absorb more heat, and fancy rotor designs can dissipate heat faster, but bigger rotor diameter and width by themselves have no effect on heat.
Here is some interesting info I found in regards to rotor design. Also, having a larger lever (e.g. caliper further away from the pivot point) increases torque and reduces the amount of energy used to stop the rotation. Less energy = less heat.


-The brakes function by converting the kinetic energy of the car into thermal energy during deceleration - producing heat, lots of heat - which must then be transferred into the surroundings and into the air stream.

- The amount of heat produced in context with a brake system needs to be considered with reference to time meaning rate of work done or power. Looking at only one side of a front brake assembly, the rate of work done by stopping a 3500-pound car traveling at 100 Mph in eight seconds is 30,600 calories/sec or 437,100 BTU/hr or is equivalent to 128 kW or 172 Hp. The disc dissipates approximately 80% of this energy. The ratio of heat transfer among the three mechanisms is dependent on the operating temperature of the system. The primary difference being the increasing contribution of radiation as the temperature of the disc rises. The contribution of the conductive mechanism is also dependent on the mass of the disc and the attachment designs, with disc used for racecars being typically lower in mass and fixed by mechanism that are restrictive to conduction. At 1000oF the ratios on a racing 2-piece annular disc design are 10% conductive, 45% convective, 45% radiation. Similarly on a high performance street one-piece design, the ratios are 25% conductive, 25% convective, 50% radiation.

-Repeated hard stops require both effective heat transfer and adequate thermal storage capacity within the disc. The more disc surface area per unit mass and the greater and more efficient the mass flow of air over and through the disc, the faster the heat will be dissipated and the more efficient the entire system will be. At the same time, the brake discs must have enough thermal storage capacity to prevent distortion and/or cracking from thermal stress until the heat can be dissipated. This is not particularly important in a single stop but it is crucial in the case of repeated stops from high speed
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      11-06-2012, 11:27 AM   #68
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BTW Gary, all this is said respectfully, it's just my understanding and not law by any measure.

I still stand by my opinion that from a performance stand point number of pistons is less important then rotor size and to your point, cooling.

Then again,I bought my Brembo GT's 98% based only on bling. But they do perform well and look good.
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      11-06-2012, 11:31 AM   #69
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Just because you guys got me looking into my options, there's also Performance Friction apparently:
http://www.1addicts.com/forums/showthread.php?t=460211

Interesting 4 pads per disc design. One piece caliper.
Looks like around 3600 front + 3500 rear?

*sigh*
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      11-06-2012, 11:35 AM   #70
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BTW Gary, all this is said respectfully, it's just my understanding and not law by any measure.

I still stand by my opinion that from a performance stand point number of pistons is less important then rotor size and to your point, cooling.

Then again,I bought my Brembo GT's 98% based only on bling. But they do perform well and look good.
Oh, number of pistons was the point? Yes, that's true. Number of pistons doesn't matter. It's the total surface area of the pistons that matters, at least for braking force.

In the stock 135i calipers, having three small pistons instead of one or two big ones might actually be causing problems. We've seen evidence of some kind of uneven or incorrect piston pressure when the brakes are stressed, which the RacingBrakes guy said was a big cause of his rotors cracking in my car and FocusedIntention's car.
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      11-06-2012, 11:44 AM   #71
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Originally Posted by MteK View Post
The more disc surface area per unit mass ... the faster the heat will be dissipated and the more efficient the entire system will be.
I haven't heard that part before but it makes sense. So a heavier rotor can absorb more heat, but a lighter one the same diameter can dissipate heat faster.
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      11-06-2012, 05:08 PM   #72
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Quote:
Originally Posted by MteK
Quote:
Originally Posted by GaryS View Post
Well, I agree with most of that with some small quibbles.

Resistance to fade depends mostly on the choice of pads. Better ducting can help some, and better rotor design can help a little.

Heavier rotors absorb more heat, and fancy rotor designs can dissipate heat faster, but bigger rotor diameter and width by themselves have no effect on heat.
Here is some interesting info I found in regards to rotor design. Also, having a larger lever (e.g. caliper further away from the pivot point) increases torque and reduces the amount of energy used to stop the rotation. Less energy = less heat.


-The brakes function by converting the kinetic energy of the car into thermal energy during deceleration - producing heat, lots of heat - which must then be transferred into the surroundings and into the air stream.

- The amount of heat produced in context with a brake system needs to be considered with reference to time meaning rate of work done or power. Looking at only one side of a front brake assembly, the rate of work done by stopping a 3500-pound car traveling at 100 Mph in eight seconds is 30,600 calories/sec or 437,100 BTU/hr or is equivalent to 128 kW or 172 Hp. The disc dissipates approximately 80% of this energy. The ratio of heat transfer among the three mechanisms is dependent on the operating temperature of the system. The primary difference being the increasing contribution of radiation as the temperature of the disc rises. The contribution of the conductive mechanism is also dependent on the mass of the disc and the attachment designs, with disc used for racecars being typically lower in mass and fixed by mechanism that are restrictive to conduction. At 1000oF the ratios on a racing 2-piece annular disc design are 10% conductive, 45% convective, 45% radiation. Similarly on a high performance street one-piece design, the ratios are 25% conductive, 25% convective, 50% radiation.

-Repeated hard stops require both effective heat transfer and adequate thermal storage capacity within the disc. The more disc surface area per unit mass and the greater and more efficient the mass flow of air over and through the disc, the faster the heat will be dissipated and the more efficient the entire system will be. At the same time, the brake discs must have enough thermal storage capacity to prevent distortion and/or cracking from thermal stress until the heat can be dissipated. This is not particularly important in a single stop but it is crucial in the case of repeated stops from high speed
Just on your point 1 for now, more torque isn't less heat, it's more POTENTIAL heat per unit of time.

Ie, it turns kinetic into heat faster is all

It's simple more braking force, not cooling/heat dissipation.
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      11-06-2012, 05:28 PM   #73
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Avoid the cheaper set ups if possible, I've always used the brembo's and found them a stark contrast to other brands, particularly rotoras, as MTek said. Although, it's your decision, either way they are all a major improvement on stock

Edit: Well this turned out to be several more pages of text than I was expecting
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      11-07-2012, 01:54 PM   #74
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Quote:
Originally Posted by int2str View Post
Just because you guys got me looking into my options, there's also Performance Friction apparently:
http://www.1addicts.com/forums/showthread.php?t=460211

Interesting 4 pads per disc design. One piece caliper.
Looks like around 3600 front + 3500 rear?

*sigh*
This is replicated by http://www.powerbrake.co.za/
Perhaps at a lower price point, I am awaiting a reply.
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"The 1-series is the last car that BMW engineered before the Germans, as a car-making culture, fell out of love with driving." - R&T 2013 135is

Last edited by andrey_gta; 11-07-2012 at 02:39 PM.
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      11-07-2012, 02:25 PM   #75
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Quote:
Originally Posted by andrey_gta View Post
This is replicated by http://www.powerbrake.co.za/
Perhaps at a lower price point.
Looks like a two piece caliper.
Couldn't find a price on their site. Any US Powerbrake dealers?
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      11-15-2012, 08:45 PM   #76
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If MSRP on the stoptech is $3200 you can most likely get it for under 3k then. But shipping to Australia would be pretty big.
We just need to get a few sets together and send them all on one single pallet.
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      11-16-2012, 04:33 PM   #77
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Quote:
Originally Posted by GaryS View Post
Oh, number of pistons was the point? Yes, that's true. Number of pistons doesn't matter. It's the total surface area of the pistons that matters, at least for braking force.

In the stock 135i calipers, having three small pistons instead of one or two big ones might actually be causing problems. We've seen evidence of some kind of uneven or incorrect piston pressure when the brakes are stressed, which the RacingBrakes guy said was a big cause of his rotors cracking in my car and FocusedIntention's car.
I checked back with FocusedIntention not too long ago regarding how he was finding the RacingBrake kit with the caliper rebuild kit, specifically asking him if there was any cracking of the rotors - he said no problems whatsoever with the new batch. Previously yes, but he seems confident that this new batch is up to the task. Wonder what the difference is?
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      11-16-2012, 06:52 PM   #78
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Quote:
Originally Posted by GaryS View Post
Oh, number of pistons was the point? Yes, that's true. Number of pistons doesn't matter. It's the total surface area of the pistons that matters, at least for braking force.

In the stock 135i calipers, having three small pistons instead of one or two big ones might actually be causing problems. We've seen evidence of some kind of uneven or incorrect piston pressure when the brakes are stressed, which the RacingBrakes guy said was a big cause of his rotors cracking in my car and FocusedIntention's car.
You can add me to the list as well. Although I'm not entirely positive my rotors cracking was directly attributable to the caliper pistons I have identical cracking on both rotors after tracking car last time out.
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      03-03-2013, 02:14 PM   #79
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Hi Gents,

This is my first post!

I was really surprised to find POWERBRAKE mentioned on this forum. I owned the company in South Africa called FORZA Racing, we specialized in Ferrari's and more importantly Ferrari Racing. We tied up with POWERBRAKE to develop a BBK kit for our F430 CHALLENGE clients. These cars came with the CCM brembo system and due to cost and reliabilty the CCM option was not viable.

In conjunction with Clive at POWERBRAKE we developed the 6 piston caliper and 350x35( I think) disc system. The results were MIND BLOWING!!!

The POWERBRAKE system out performed the Brembo CCM in all aspects but most importantly the cost saving was just astounding!!! The brakes had way better feel/feed back on the pedal. The stopper power was definitely up. We tested many pads including Hawk CARBOTEC and eventually we settled on ENDLESS PADS.

I know most people in the "civilized world" couldn't imagine a small company at the tip of Africa could develop a BBK that can compete with The likes of Brembo/AP/Alcon etc but I can say I have raced on all these brands and POWERBRAKE is as good if not better in certain aspects.

PS: I now work for BMW dealer as the SErvice Manager and I just bought myself a brand new 135 N55!
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      03-03-2013, 03:02 PM   #80
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Hi Gents,

This is my first post!

I was really surprised to find POWERBRAKE mentioned on this forum.
Thanks for the feedback on Powerbrake. They do seem to service numerous racing teams local to them with great results. It certainly peaked my interest and i tried contacting them.

Unfortunately, they did not reply to my 3 basic inquiries via their email, SA website, or USA website. Its unfortunate, but I guess their local market is more of a priority. Perhaps you can contact them on behalf of BMW e82 135i and inquire into their options, shipping cots and such.
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In-progress: e46 m3 trans mnt, e36M lip Wishlist: m3 susp, n55 eng mnt, headers, LSD, finn dif e60


"The 1-series is the last car that BMW engineered before the Germans, as a car-making culture, fell out of love with driving." - R&T 2013 135is

Last edited by andrey_gta; 03-03-2013 at 04:16 PM.
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      03-04-2013, 02:10 PM   #81
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[quote=Unfortunately, they did not reply to my 3 basic inquiries via their email, SA website, or USA website. Its unfortunate, but I guess their local market is more of a priority. Perhaps you can contact them on behalf of BMW e82 135i and inquire into their options, shipping cots and such.[/QUOTE]

Spoke to Clive at POWERBRAKE about your post. They should be in contact with you ASAP!!!

Not to speak on POWERBRAKE's behalf but I think what they are experiencing is what happens to many small niche companies on the verge of taking the next major step with regards growth... They have just grown to quickly to keep up with demand I guess.

I know the DAKAR RALLY was a massive project for them And my guess is your enquiries probably came through when they were meeting the deadlines for TOYOTA MOTORSPORT.

what I can tell you is that i'm definitely gonna do a POWERBRAKE BBK... But first I'm gonna do the M suspension then JB4 stage 2 with FMIC, DP, INTAKE, WATER METH, OCC...
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      03-04-2013, 05:52 PM   #82
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this is coming of waaaayyy like an adertisement, with the highlighting of events the powerbrakes have been used in haha

could well be enthusiasm though :P
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      03-04-2013, 11:42 PM   #83
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this is coming of waaaayyy like an adertisement, with the highlighting of events the powerbrakes have been used in haha

could well be enthusiasm though :P
Just a fan flinchy...

Definately enthusiasm...

Last edited by OscarDeo; 03-05-2013 at 12:05 PM.
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