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      01-27-2020, 03:09 PM   #1
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Essex AP Racing front 9668-Brake Ducting backing plates?

I'm about to pull the trigger on the fronts, but wanted to run a dedicated ducting setup as well. Does anyone make a backing plate that works with this kit?
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      01-28-2020, 12:49 PM   #2
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Quote:
Originally Posted by SEAT TIME RULES View Post
I'm about to pull the trigger on the fronts, but wanted to run a dedicated ducting setup as well. Does anyone make a backing plate that works with this kit?
Overall, our suggestion is usually to try our system first without ducts. You may find that you don't have to full around with hoses that tear, wires hanging out, constant taping, rubbing on full lock in the pits, etc. If you can eliminate all of that, it's a win. If you find that you're burning through pads and discs at a fast rate, then consider ducts. That isn't the case with most of our customers. Most find that our system works fantastic without ducts. A good way to know is to collect temperature data, and share that data with us for interpretation. Thanks!

The reason for the above is, most of the duct setups we've seen on production cars do more harm than good:
  • They duct air to the wrong location (onto the disc face)
  • They don't move an adequate amount of air from the front end (due to convoluted path, obstructions, etc.)
  • The mounting plate traps or reflects heat back onto the inner disc face

All of the above create a temperature gradient in the disc, where one of half or part of the disc is running cooler than the other. That causes premature cracking. From what we've seen, those with poorly integrated ducts crack discs much faster than those who don't have any ducts at all. We've backed this up with many, many miles of customer experience/feedback, as well as our own testing at Carolina Motorsports Park.

In pro racing, things are a bit different, as the cars are built to accommodate a proper duct setup. Some of them have as many as three four inch ducts going to the proper locations on the calipers and discs. They also gather air in the proper pressure zones, and they are able to get that air to where it needs to go via a direct path in adequate volume. They aren't contending with oil coolers, wiper washer bottles, etc.

Finally, pro teams have tight control over their duct setup. They're gathering temperature data and know how much and when to let the system have more air. On some tracks that might mean taping the ducts off completely at the front of the car. At others, part of the way taped, or fully open. That has to do with the track and car configuration.

Heat doesn't kill discs. What kills discs is wild temperature swings. If you could run your disc up to about 1000F and leave it there all day, a proper racing disc would be quite happy. Unfortunately, the actual temp is going to be oscillating considerably. The rapid contraction and expansion of the iron is what causes stress fractures. For example, long, fast straights followed by tight turns (think Road America or Watkins Glen) will blast a ton of air through a duct into your disc and cool it down quite a bit. Then you stand on the brakes, huge temperature spike, followed by more rapid cooling. If you don't have the ducts, the discs may hit a higher peak, but the temps aren't falling off a cliff every time you take to the straight.

Not having ducts is a bit counter-intuitive at first, but when you consider what is causing the stress, it makes sense.

Last edited by jritt@essex; 01-28-2020 at 01:00 PM..
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      01-28-2020, 05:27 PM   #3
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Quote:
Originally Posted by jritt@essex View Post
Overall, our suggestion is usually to try our system first without ducts. You may find that you don't have to full around with hoses that tear, wires hanging out, constant taping, rubbing on full lock in the pits, etc. If you can eliminate all of that, it's a win. If you find that you're burning through pads and discs at a fast rate, then consider ducts. That isn't the case with most of our customers. Most find that our system works fantastic without ducts. A good way to know is to collect temperature data, and share that data with us for interpretation. Thanks!

The reason for the above is, most of the duct setups we've seen on production cars do more harm than good:
  • They duct air to the wrong location (onto the disc face)
  • They don't move an adequate amount of air from the front end (due to convoluted path, obstructions, etc.)
  • The mounting plate traps or reflects heat back onto the inner disc face

All of the above create a temperature gradient in the disc, where one of half or part of the disc is running cooler than the other. That causes premature cracking. From what we've seen, those with poorly integrated ducts crack discs much faster than those who don't have any ducts at all. We've backed this up with many, many miles of customer experience/feedback, as well as our own testing at Carolina Motorsports Park.

In pro racing, things are a bit different, as the cars are built to accommodate a proper duct setup. Some of them have as many as three four inch ducts going to the proper locations on the calipers and discs. They also gather air in the proper pressure zones, and they are able to get that air to where it needs to go via a direct path in adequate volume. They aren't contending with oil coolers, wiper washer bottles, etc.

Finally, pro teams have tight control over their duct setup. They're gathering temperature data and know how much and when to let the system have more air. On some tracks that might mean taping the ducts off completely at the front of the car. At others, part of the way taped, or fully open. That has to do with the track and car configuration.

Heat doesn't kill discs. What kills discs is wild temperature swings. If you could run your disc up to about 1000F and leave it there all day, a proper racing disc would be quite happy. Unfortunately, the actual temp is going to be oscillating considerably. The rapid contraction and expansion of the iron is what causes stress fractures. For example, long, fast straights followed by tight turns (think Road America or Watkins Glen) will blast a ton of air through a duct into your disc and cool it down quite a bit. Then you stand on the brakes, huge temperature spike, followed by more rapid cooling. If you don't have the ducts, the discs may hit a higher peak, but the temps aren't falling off a cliff every time you take to the straight.

Not having ducts is a bit counter-intuitive at first, but when you consider what is causing the stress, it makes sense.
THX 4 the thoughtful post....I'm aware of all of the above. When I ran at the Glen in a previous M3 I would block off my ducting. I wasn't needed. On tracks like Thompson & NHMS it is needed. Those are both brake intensive courses with short straights that don't cool down the rotors pads and lines enough. Last, I also use ducting because it extends my front pad life aprox 25-35%.
My 1st scheduled event TY is at NHMS and hope to have your fronts on by then.
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      01-29-2020, 10:51 AM   #4
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Quote:
Originally Posted by SEAT TIME RULES View Post
THX 4 the thoughtful post....I'm aware of all of the above. When I ran at the Glen in a previous M3 I would block off my ducting. I wasn't needed. On tracks like Thompson & NHMS it is needed. Those are both brake intensive courses with short straights that don't cool down the rotors pads and lines enough. Last, I also use ducting because it extends my front pad life aprox 25-35%.
My 1st scheduled event TY is at NHMS and hope to have your fronts on by then.
COTA is tough on brakes as well. I ran the 9668/9449 kit on my M4 and experienced no fading issues. It's a well designed kit. You'll be pleased.
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      01-29-2020, 01:53 PM   #5
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Quote:
Originally Posted by SEAT TIME RULES View Post
THX 4 the thoughtful post....I'm aware of all of the above. When I ran at the Glen in a previous M3 I would block off my ducting. I wasn't needed. On tracks like Thompson & NHMS it is needed. Those are both brake intensive courses with short straights that don't cool down the rotors pads and lines enough. Last, I also use ducting because it extends my front pad life aprox 25-35%.
My 1st scheduled event TY is at NHMS and hope to have your fronts on by then.
No worries. It sounds like you have it under control. Excellent.
Let us know if anything pops up that you need.
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