11-17-2019, 06:59 PM | #1 |
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Front Brake Scoops
This past summer, at the same time I had a shop install a jack point in the center of each side of my car, I also had them do something to get more air into the interior of my front brake rotors.
I did this because I’ve been experiencing very high rotor and caliper temperatures ever since I began running the car at the track. Even though there is air being ducted through the front bumper cover and into the area where the front braking components reside, little of that air is able to make its way into the center of the rotors and then out through the vanes. Without sufficient movement of air along that path, the rotors and calipers are going to get pretty hot - maybe hot enough to discolor the calipers and, possibly, burn them down. Compared to the E36 and E30 that I used to run, there’s remarkably little room to channel incoming air to the center of the front rotors. There’s insufficient room for a 3” or 2” brake duct hose, and the car’s front knuckles/carriers effectively block almost all access to the interior of the rotors. Those parts can be seen at #2 in this realoem diagram: https://www.realoem.com/bmw/enUS/sho...diagId=31_0956. The work the shop determined would be most effective in moving at least some air into the center of the rotors was to fabricate what they called an air “scoop”. This part can be seen in the photos immediately below. This is a shot of the air scoop from the front showing its position relative to some of the suspension and braking components: This one shows a close-up of the scoop; it gives an idea of how small the opening for incoming air is with the knuckle/carrier taking up so much space: This shows the scoop from the rear, giving a glimpse of the brake duct exit in the bumper as well as showing once again the smallness of the opening into the center of the rotor: The scoop is aligned such that it captures a portion of the column of air flowing out of the brake duct exit in the bumper assembly and redirects that subset of air into the center of the rotor. The shop told me that, relatively, it would have a greater effect upon caliper temperature than it would rotor temperature. I’m not sure where I’ve managed to misplace the specific before and after temperature data; although, if I look at a rotor paint temp chart and a caliper temp strip, I’ll quickly be able to offer up the before and after temperature ranges for both components. If anyone wants that data, please feel free to ask, and I'll pull it together. The bottom line is that both the rotors and the calipers are running a decent amount cooler than they were, but nowhere nearly as cool as I’d like them to run. Update: see post #20 for the before and after temperature data. The next step is going to be to take out the caliper pistons and examine the dust boots and piston seals. Regardless of their condition, we’ll probably just go ahead and replace the boots and seals with high-temp units. The principal reason for this is that my next event will be a two-day open-lapping event at Watkins Glen, a much higher-speed track than is the track I’ve been running since I had the car built. That’s Mid-Ohio, a handling track with only one high-speed braking zone, whereas the Glen has five high-speed braking zones and places high demands on a car’s braking system. FWIW, BMW sells a caliper repair kit that includes only the dust boots. If you want caliper seals from BMW, you have to buy new calipers. That’s not necessarily a problem, as Brembo makes the boots and seals that go in their calipers, but the shop tells me they need to take measurements before I can be assured of ordering the correct sizes of those parts. In the event someone else ends up needing the data, I’ll post the caliper piston sizes here once they’ve been measured. –––––––––––––––––––––––––––––––––––––––––––––––––– Update: Here are three photos of a brake scoop taken when it was off the car:
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2017 M240i: 25.9K, 28.9 mpg, MT, Sunroof Delete, 3,432#, EB, Leather, Driving Assistance Package, Heated Front Seats | Sold: E12 530i, E24 M635CSi, E39 520i, E30 325is, E36 M3 (2)
TC Kline Coilovers; H&R Front Bar; Wavetrac; Al Subframe Bushings; 18X9/9˝ ARC-8s; 255/35-18 PS4S (4); Dinan Elite V2 & CAI; MPerf Orange BBK; Schroth Quick Fit Pro; Full PPF Last edited by dradernh; 01-24-2022 at 05:03 PM.. Reason: Show an Unmounted Brake Scoop |
11-18-2019, 12:17 AM | #2 | |||
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(*) for now very wide front tires (less need to brake), plus 355mm rotors seem to do the trick. |
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11-18-2019, 01:43 AM | #4 | |
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The local shop I use has suggested an old brake cooling trick: water sprayed wherever it's needed to keep the brakes cool. If I was going to keep running the car and this was a serious-enough issue, I'd probably look into that. As it is, I'm doing only one or two more events before hanging my helmet up, and so far the brakes are working well despite the seemingly too-high temperatures. Heck, the calipers still look like new when they're clean - they have no visible discoloration at all. I'm most curious to see the conditions of the dust boots and piston seals. 2) I think there may be another attachment point. I'll take a look the next time the wheels are off, and if it's there I'll shoot and post it.
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2017 M240i: 25.9K, 28.9 mpg, MT, Sunroof Delete, 3,432#, EB, Leather, Driving Assistance Package, Heated Front Seats | Sold: E12 530i, E24 M635CSi, E39 520i, E30 325is, E36 M3 (2)
TC Kline Coilovers; H&R Front Bar; Wavetrac; Al Subframe Bushings; 18X9/9˝ ARC-8s; 255/35-18 PS4S (4); Dinan Elite V2 & CAI; MPerf Orange BBK; Schroth Quick Fit Pro; Full PPF Last edited by dradernh; 11-18-2019 at 01:54 AM.. |
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11-18-2019, 07:47 AM | #5 |
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First, I'm probably wrong. But I thought proper cooling on vented disks involved ducting cooling air to the outer periphery of the disc. When the intake tubes connect to the brake shield the brake shield is molded so that the channel travels outward to the disc outer edge.
The idea is to get increased airflow across the outside circumference of the disk and that sucks the hot air inside the rotor chambers to get extruded. |
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11-18-2019, 09:23 AM | #6 | |
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Sufficient air is frequently supplied by a 3" hose that forces outside air from the front of the car into the interior of the rotor. That air then flows through the rotor's vanes and exhausts quite a bit of the heat that's built-up in the rotor. You can read and see more detail in the Internal Vane Quantity and Quality section on this page: https://www.essexparts.com/essex-des...87M2f80M3f82M4
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2017 M240i: 25.9K, 28.9 mpg, MT, Sunroof Delete, 3,432#, EB, Leather, Driving Assistance Package, Heated Front Seats | Sold: E12 530i, E24 M635CSi, E39 520i, E30 325is, E36 M3 (2)
TC Kline Coilovers; H&R Front Bar; Wavetrac; Al Subframe Bushings; 18X9/9˝ ARC-8s; 255/35-18 PS4S (4); Dinan Elite V2 & CAI; MPerf Orange BBK; Schroth Quick Fit Pro; Full PPF |
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11-18-2019, 12:36 PM | #7 | |
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I'm questioning whether increased air flow to the rotor center hub area actually causes turbulence and minimizes hot air drawn out through the outer vents. But, I haven't read the above closely enough to be certain. Last edited by overcoil; 11-18-2019 at 04:01 PM.. |
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11-20-2019, 05:36 AM | #9 |
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It's off this page: https://www.apmotorsport.co.uk/produ...r-cp9440-front.
AP Motorsport also sells the M4 GTR brake cooling kit seen below. Another driver I met at the track has an M2 with both Essex Parts' AP Racing front brake calipers and a similar brake cooling kit feeding air into his front rotors via both 2" and 3" hoses. His setup would work for an endurance race. I limit my sessions to 15 minutes.
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2017 M240i: 25.9K, 28.9 mpg, MT, Sunroof Delete, 3,432#, EB, Leather, Driving Assistance Package, Heated Front Seats | Sold: E12 530i, E24 M635CSi, E39 520i, E30 325is, E36 M3 (2)
TC Kline Coilovers; H&R Front Bar; Wavetrac; Al Subframe Bushings; 18X9/9˝ ARC-8s; 255/35-18 PS4S (4); Dinan Elite V2 & CAI; MPerf Orange BBK; Schroth Quick Fit Pro; Full PPF |
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11-23-2019, 06:58 PM | #11 |
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Once the shop sends me a bill, I'll post the cost here. Given the shop's history of racing success, and what it's built and still builds, I'm grateful every day that the invoice has yet to hit my inbox!
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2017 M240i: 25.9K, 28.9 mpg, MT, Sunroof Delete, 3,432#, EB, Leather, Driving Assistance Package, Heated Front Seats | Sold: E12 530i, E24 M635CSi, E39 520i, E30 325is, E36 M3 (2)
TC Kline Coilovers; H&R Front Bar; Wavetrac; Al Subframe Bushings; 18X9/9˝ ARC-8s; 255/35-18 PS4S (4); Dinan Elite V2 & CAI; MPerf Orange BBK; Schroth Quick Fit Pro; Full PPF |
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12-19-2019, 06:55 PM | #12 |
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Sub'd for more!
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01-13-2020, 12:46 PM | #13 |
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I added three photos of an unmounted brake scoop to the first post. They show that there is only one attachment point, the hose clamp.
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2017 M240i: 25.9K, 28.9 mpg, MT, Sunroof Delete, 3,432#, EB, Leather, Driving Assistance Package, Heated Front Seats | Sold: E12 530i, E24 M635CSi, E39 520i, E30 325is, E36 M3 (2)
TC Kline Coilovers; H&R Front Bar; Wavetrac; Al Subframe Bushings; 18X9/9˝ ARC-8s; 255/35-18 PS4S (4); Dinan Elite V2 & CAI; MPerf Orange BBK; Schroth Quick Fit Pro; Full PPF |
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01-13-2020, 03:03 PM | #14 |
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01-13-2020, 05:17 PM | #15 | |
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All I can say is that they didn't come across as being heavy (the aluminum stock from which they were made isn't very thick). I do know that if the shop thought a further attachment was warranted, they would have added it.
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2017 M240i: 25.9K, 28.9 mpg, MT, Sunroof Delete, 3,432#, EB, Leather, Driving Assistance Package, Heated Front Seats | Sold: E12 530i, E24 M635CSi, E39 520i, E30 325is, E36 M3 (2)
TC Kline Coilovers; H&R Front Bar; Wavetrac; Al Subframe Bushings; 18X9/9˝ ARC-8s; 255/35-18 PS4S (4); Dinan Elite V2 & CAI; MPerf Orange BBK; Schroth Quick Fit Pro; Full PPF |
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01-24-2020, 11:47 AM | #16 |
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It's be awesome if your shop would sell them here or if they have a website.
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01-24-2020, 11:55 AM | #17 |
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Unfortunately, it's not that kind of a shop. I'm afraid these are one-offs.
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2017 M240i: 25.9K, 28.9 mpg, MT, Sunroof Delete, 3,432#, EB, Leather, Driving Assistance Package, Heated Front Seats | Sold: E12 530i, E24 M635CSi, E39 520i, E30 325is, E36 M3 (2)
TC Kline Coilovers; H&R Front Bar; Wavetrac; Al Subframe Bushings; 18X9/9˝ ARC-8s; 255/35-18 PS4S (4); Dinan Elite V2 & CAI; MPerf Orange BBK; Schroth Quick Fit Pro; Full PPF |
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01-24-2020, 12:15 PM | #18 |
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01-24-2020, 03:59 PM | #19 | |
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If anyone goes that route, I recommend asking for an estimate first. As these scoops made only a modest difference in rotor and caliper temps, I doubt it's worth spending more than a moderate amount on them.
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2017 M240i: 25.9K, 28.9 mpg, MT, Sunroof Delete, 3,432#, EB, Leather, Driving Assistance Package, Heated Front Seats | Sold: E12 530i, E24 M635CSi, E39 520i, E30 325is, E36 M3 (2)
TC Kline Coilovers; H&R Front Bar; Wavetrac; Al Subframe Bushings; 18X9/9˝ ARC-8s; 255/35-18 PS4S (4); Dinan Elite V2 & CAI; MPerf Orange BBK; Schroth Quick Fit Pro; Full PPF |
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02-10-2020, 01:06 PM | #20 | |
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The temperature paint and caliper strips don't provide anything like a precise reading, so values are approximate. The original rotor temps were in the neighborhood of 1500-1600°F, and I estimate the temp reduction to be ~100°F. My estimates for the calipers is that prior to installing the scoops they were running around 375°F and that was reduced by less than ~50°F. This was measured with Genesis Caliper Temp Strips placed on the rounded, top part of the outside leading front caliper piston.
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2017 M240i: 25.9K, 28.9 mpg, MT, Sunroof Delete, 3,432#, EB, Leather, Driving Assistance Package, Heated Front Seats | Sold: E12 530i, E24 M635CSi, E39 520i, E30 325is, E36 M3 (2)
TC Kline Coilovers; H&R Front Bar; Wavetrac; Al Subframe Bushings; 18X9/9˝ ARC-8s; 255/35-18 PS4S (4); Dinan Elite V2 & CAI; MPerf Orange BBK; Schroth Quick Fit Pro; Full PPF |
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03-01-2020, 11:29 AM | #22 |
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I'm hoping there is room to run a cooling hose back and thru the inside wheelwell skirts. I know on the msports there is a kind of vent duct already there, so it seems to be a matter of finding a way to plumb into the back side of the hub/rotor rather than just dumping into wheelwell.
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