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That is NUTS! I was going to say "If it was a good idea someone would have done it." Uh ok someone did do it... I have to say that I'm amazed. I'll grant that it is no doubt effective, given the density of water and therefore the far higher heat transfer capability. But complicated! If I was going to do it, there would be a temperature sensor at each rotor, a computer deciding how much water to squirt at each based on how hot, etc. etc. etc. I wonder how long the 2 gallon tank lasts - sure it's fine for a Time Attack car but I doubt it is practical for for anything longer, especially with water weighing about 8lb/gallon. If the driver had to deal with a "changing pedal" in just 5 laps then there's obviously not enough brake cooling, I wonder why they chose the water cooling vs. just improving airflow to the rotors, which is simpler and doesn't add the weight of a tank of water. Maybe there's about as much room to route ducting as in the R56.
The concept brings to mind the old Chaparral 2J car that Jim Hall built, a radical idea that was incredibly effective but wasn't practical. (Many years ago I got to do laps with Jim Hall as my coach, what a thrill that was!) So instead I'll say "just because you can, doesn't mean you should."
Last edited by squawSkiBum; 12-19-2018 at 08:29 PM.
I'm going to pre-disclaim this with "I'm not a fluid mechanics engineer, what do I know":
It looks like the transitions from circular to rectangular segments result in different cross section areas at different areas. That's going to cause the airflow to slow down (through expansion areas) and speed up (in constrictions). It also looks like there are several such transitions. Won't that add turbulence, which would impair flow? Does your duct have a consistent cross section areas from end to end? If not, maybe that's something to work on to try to get flow up.
The changing shape could also be an issue, as the disruptions to laminar flow would create turbulence as well. Given the tight areas you're working in, there may not be much to be done about this, and it looks like you've been evolving your designs to smooth out flow.
You are absolutely correct - one of the things I tried to do was to keep the duct cross section area reasonably constant, but for the part that had to squeeze between the transmission and the subframe there was just no way, the rectangular part (actually slightly trapezoidal) ended up being about 80% of the area of the round hose. Every area change and every bend will affect the flow. And when the sway bar crushes the flexible duct to about 1/2 the area, that's a problem!
Moving on to the new idea - the open end of the scoop is about 150% of the area of the smaller rectangular part that it transitions into, and the rectangular part is about the same area as the flexible duct. The idea is to smoothly accelerate the flow into the smaller rectangular area and then transition to the round cross section of the same area. It is all a tradeoff - the transition from rectangular to round would ideally be more gradual, but then it wouldn't fit in the space available. There's also the constraint of the capabilities of the 3D printer and my fabrication skillset - someone with welding skills and equipment to form tubing would probably take a different approach.
Anyway, I have loved reading about your project and hope you find success!
Thanks! I appreciate all of you reading along and commenting.
(Many years ago I got to do laps with Jim Hall as my coach, what a thrill that was!) So instead I'll say "just because you can, doesn't mean you should."
Say What???!!!!
Oh, that had to be a thrill! Thinking back to those days, the skill that those drivers had, must have been amazing. Today, we have electronics, big wheels and tires and brakes that were not even thought of back then. Can you imagine what it was like to slow a car, like that, from close to 200 mph using brakes that weren’t much better than the Wilwood 12.2” BBK.that were stuffed into 15” wheels. I think our MINI Cooper brake cooling issue pale in comparison.
As for the GTR, I would guess that they were forced into the water cooling as they may be dealing with the same lack of space that we are dealing with. Also, if you think our DTC eLSD is a pain and hard on our front brakes, the GTR is likely twice as bad given all of the other things that the car does, electronically, with the brakes to make it do what it is supposed to do.
One of the issues that I have pondered when trying to route brake duct hose to the MINI’s wheels was the amount of motion the front wheel goes through when turning and with up/down motion. I was at a loss as to how to get enough flexibility in the hose to accommodate this motion. I am curious as to how you are fairing with this issue...
I wonder how much benefit, if any, there is to the vents between the hub and disc on 2 pc units like the wilwoods. I know that they make directional rotors for aftermarket brake systems as well. I'm just curious if there are any options to keep the factory calipers and add an aftermarket rotor?
I'm guessing it would be extremely risky to add vents in the factory rotor 'hat' area......
Have fun,
Mike
I can't seem to attach a pic, here is a link to wilwood
I wonder how much benefit, if any, there is to the vents between the hub and disc on 2 pc units like the wilwoods. I know that they make directional rotors for aftermarket brake systems as well. I'm just curious if there are any options to keep the factory calipers and add an aftermarket rotor?
I'm guessing it would be extremely risky to add vents in the factory rotor 'hat' area......
Have fun,
Mike
I can't seem to attach a pic, here is a link to wilwood
This has vented space between each of the rotor mounting tabs. DBA makes 2 piece rotors for cars and the stock brake calipers. Not sure if they make them for MINI but here is an example: https://www.tirerack.com/brakes/brak...181226174721:s
There isn’t much of a vent slot between the hat and rotor.
Not sure which is better. The Wilwood one looks “neater”. However, I tend to think that the TCE hat is better as it does better at making sure the air is funneled up and into the vent slots on the rotor.
Personally, on my brakes that I have fab’ed my own version of F1 or Indy Car style brake ducts, I see evidence that air is blowing from the inside to the outside of the Wilwood style hats I have. This probably means I am loosing air that would otherwise be going through the rotor vane slots.
If you have a good source of high pressure air coming in through brake ducts and into the base of the rotor slots, you probably want to have the solid rotor hat so you don’t loose any of that air. This is probably the best designed brake ducting I have seen; http://allracingcars.com/porsche-962/
About half way through the pictures that are posted it shows the Porsche with the front nose off and you can see how the brakes are cooled. Now if we could just do that on the MINI...
I also remember on the 962 era cars that BBS had wheel 'Fans' that were mounted to the face of the wheel to assist with airflow. At the time, I never looked close enough to see how they worked, but I'm assuming that they were pulling air out of the wheel.
Its interesting to have these discussions, really gets you thinking. I wonder if just circulating the air inside the wheel would help, like mounting a fan on the axle to blow toward the wheel. Totally random thought.....
I think one car with the fan wheels was the C4 Corvette. Each wheel was different. The fronts were narrower than the rears and the lefts couldn’t be used on the right side and vice versa. This option didn’t last long.
I think the Ultra Cool Brake Fan I posted the link to (above) is along the lines of your idea. But it is on the outside of the rotor not the inside. For the MINI, however, I wonder if your idea of a fan on the axle would be much different from the MINI brake duct that already dumps ‘tons” of air into that area. I think the issue with the MINI brakes is to get large amounts of air directed into the base of the rotor vanes. However, I also wonder if there could be a way to duct the air off your axle fan, but with only inches to work with??? Hmmm, more to think about...
A thought that I went with was that I figured that all of the air that the MINI ducts are dumping into the back side of the wheel is getting spun-up with the wheel. SoI made a scoop for each wheel, attached to the dust sheild, that is intended to capture some of that air that is spinning with the wheel and it directs that captured air to the base of the rotor vanes. The opening for the scopes faces opposite the rotation of the wheel and is close to the wheel ID. So my thought is that the velocity of the air that is is going along with the rotating wheel ID will force some of that air into the scoop, which is then directed into the base of the rotor. Does it work? Yes, it does help (no scientific proof of that, though) but it by no means is a fix for the brake cooling these cars need. I could improve upon them by having them be closer to the wheel and to make them larger. But that is for another day, after I see whether the thicker rotors I now have make a big difference.
It has been a while, but finally here's a little bit of progress. We had an epic ski season, then sailing season started, too many distractions!
I covered the new scoop shown in post #93 with two layers of carbon, then I had to figure out how to attach it. If I was Nik Blackhurst from Project Binky, I'd just cut up some metal on the bandsaw, bend it up, and then weld a bracket. But I don't have a bandsaw, I don't have a welding rig, and I don't know how to use one anyway. After a bit of thinking, I figured out a simple solution. Some quick measuring, a 3D print to check, then I 3D printed a form for a simple bracket. 6 layers of carbon cloth and some resin, a bit of cleanup with the dremel, and presto I have a bracket.
A bit of hardware to attach the bracket to the scoop and a long zip tie hold the scoop in place. Sorted! (I really have been watching too much Project Binky...)
Here's the entire system put together from the back side. Time for some testing once the rain stops.
I have also installed Fusion360 so time to start learning a new CAD tool. I'm thinking about re-designing the duct that goes between the transmission and frame to continue higher and get enough space above the sway bar.
Man I need to read this thread from the beginning, Haha. It's been so long since I've followed this and looks like there have been some changes since the beginning.
It has been a while, but finally here's a little bit of progress. We had an epic ski season, then sailing season started, too many distractions!
Hmmmm... Epic ski season.... Distractions ... Bah, Humbug
We have a ski area here (Jay Peak) that will rival any western area for snow fall totals (in the range of 400 inches) and this season was epic for them also. Epic snow fall total, epic rain fall and epic cold.... All which turned into epic Northeast Polished Powder....
Glad you got to enjoy your epic season....
Now, back to work! There are a bunch of us who are entering into withdrawals from not having these creative posts to read in a while. (We are all going to have real problems when Project Binky is done.... )
I saw news casts of a few buried buildings at that way. Outstanding!
Then you know the places I ski. It has probably changed a bit with the opening of glades in each of the areas. My favorites are Magic Mtn,, front 5 at Stowe (yes, 5 if you include the Lookout double), and Smuggs
I did get to ski a 20” dump this past season at Gore and the season before that I climbed Hunter to ski a 40” dump (they lost power just before I got on the lift). If you look hard enough you’ll find unicorns do exist.
I have been driving with this on the left side for about a week now with no problems, except for very slight contact of the hose on the inside of the wheel when turned all the way to the left, I can see where the brake dust has been cleaned off the inside of the barrel. Today I got a chance to try to get the brakes heated up, I drove up a local twisty road, turned around at the top, and drove back down again. Toward the botttom I got stuck behind some slow traffic so the brakes cooled off a bit but still when I stopped to check temperatures, the highest I recorded on the left side was 265F, highest on the right was 295F. So it seems to be helping, but not a huge amount.
Some experiments with the shop vac blowing air at the front of the car gave me some idea why - first, the ducts on the bumper do a great job of dumping air into the wheel well. Second, the placement of the scoop on the lower control arm puts it right behind a part of the front air dam that hangs down in front of the wheel, that plus the car being lowered means there's probably not a lot of flow at the scoop. I decided that my previous concept should work better since the front ducts gather so much air, so I'm going to revise the design of the duct to get past the transmission so that it stays above the sway bar. I'm working on learning Fusion360 which once I learn it should be easier for modeling what I need.
I had wondered how well the scoop would work. The idea of lowering the car and adding air dams and splitters is to reduce the amount of air flow under the car. Well, lowering is to lower the CG, but, as you noted, it also reduced air flow under the car.
The hose to the rotor seemed tight to me and I was waiting for you to run it a bit to ask if it had enough flex to handle the rotation of the steering knuckle. It sounds like it does, but maybe it is a bit too tight? Also, the hose that I have bought seems very stiff. I think it is a double wall. Have you found some hose that is reasonably “soft” for that section?
A side thought... That scoop arrangement got me wondering if there was a way to use what you have done from the front, but come out into the wheel well just before that frame by the transmission. Then go down to where the scoop is on the control arm. Instead of a scope have an elbow upward and connects to the rest of that stuff you made to go under the control are and then to the brake rotor. Somewhere in there you will need to use a short hose to accommodate the control arm movement.
I know this would still have a lot of bends, but if you can make it smooth, that should help with air flow and you can make it as large as you want and/or will fit. A lot of the problem with the hose is the inside surface roughness. Having less hose should improve air flow.
The name Nik Blackhurst has come up in a few discussion I have been in, including this one. I thought I would share my “Nik Blackhurst” moment:
This my modified brake dust shield. The face you are looking at goes inboard. The quarter round scoop at the top catches air from the MINI brake duct. The scoop center left faces down and catches are that is rotating with the wheel Scoop that catches air off the wheel. Outlets to the brake rotor vanes.
Thanks for the better pictures - though Nik Blackhurst, Lord Commander of the Order of the Bracket, might not want to have his name mentioned anywhere near that... not that I have any welding skills at all, so you're way ahead of me!
Thanks for the better pictures - though Nik Blackhurst, Lord Commander of the Order of the Bracket, might not want to have his name mentioned anywhere near that... not that I have any welding skills at all, so you're way ahead of me!
I like the simplicity of your approach.
And He would run like crazy in the other direction if he found out that none of that was welded; it was brazed...
(note the gold-bronze coloring where the paint has flaked off in spots in the joints)
BTW - There is a 3rd deflector mounted to the bolts that mount the Wilwoods to the steering knuckle. I know I am repeating myself here, but this was all done because I found that, without the dust shield, the air blowing out of the MINI brake ducts was cooling the inside a lot more than the outside. This resulted in the outside of the rotor badly cracking. But, I still needed to get cooling into the rotors and couldn’t figure out how to get the hose over to them. Glad you are working on that one!
My approach was also one of “death by a thousand cuts”. As you have found, there is also little space to get air into the base of the rotor vanes. The best I could do was these relatively small openings in the dust shield. So, I figured the more small openings I could make, the better the cooling would be.
My conclusion was that they are less effective than they could be. MINI could have done better with designing and testing them.
The other thing I noted while I was in the wheel well of my F56 it looked like there was no room for real brake ducts similar to the problem on the R56. However, I know that the IMSA ST class race MINIs had really nice brake ducts with what I think was 2.5” hose going to each brake.
It just came to mind to see what the R56 MINI Challenge cars in the UK use for brake cooling. I haven’t seen (haven’t looked too hard either) anything about them. All 3 generations of MINIs are raced over there and they have to be doing something to cool the brakes. Might be fun to look into.
Last edited by Eddie07S; 07-16-2019 at 06:43 AM.
Reason: Edits
Here is how effective mine are, 4mm difference after 80 laps on vir south. my passenger side duct was pinched and not flowing like it should have. The pad even blistered a little, it was flowing air but not as much
12-19-2018, 07:20 PM
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