Brake Ducting

[Ron Earp]

Those hats look exactly like what we make. They are easy to do and we fix them on studs so they are easy to bolt off when time for a rotor change. There are many varitions of doing these including using the back plate like in the yellow car in the first picture, so I doubt there is a "original" way to do them. Thanks for the pics!!!!

Ron

[Gary Gibbs]

That type of disks mount is well suited for solid disks, but it is not the best for vented disks. You should pump the air from inside of the hat to out the vents. See Carroll Smith books.

[Ron Earp]

I agree, unfortunately with the cars we're racing in SCCA we're stuck with a large number of solid disks. :-(

[Alain Vanhollebeke]

On my "ITE" SCCA car I have always forced air to the claipers and brake pads- primarily,,,,and add a secondary duct for the rotor.....

......my theory being that it is more important to keep the brake fluid in the caliper from getting too hot ,,,,,,,,than the rotor surface,,,,as the rotor is designed to get hot but,,,,,,
too much heat transferred to the fluid makes for interesting braking at times.

Just my 2 cents on the subject,,,,,all I am saying is don't overlook keeping the caliper/pads cool as they will transfer the heat directly to your fluid.

[Richard Timte]

All,

The ducting of air to the brakes the modern way is one reason why I upgraded the front suspension to include the '99 Lola Indy uprights. Here is a picture from the front showing the air duct coming though the middle of the upright and feeding cold are to the inside of the rotor.


Here is a view from the back showing the sheet metal work and the brake duct mounts.



Of course the added benefit of being pin drive helps with the conversion to 6 pin drive wheels.

[Ian Anderson]

I was just thinking about the content of this post (I know I shouldn't think!) but back in the 60's brake pads had a large content of asbestos.Now this is not allowed for obvious health reasons but then back then asbestos was also used for fire fighting suits as it did not transfer heat to the wearer.

So did the asbestos in the pads in the 60's negate the need to cool the calipers and only cool the disks as the asbestos slowed / stopped the heat transfer to the caliper / fluid? Potentially the newer materials do the same but I am not sure of the content on current pads.

Ok so I'll stop thinking again as my brain hurts

Thanks
Ian

[John W]

It looks to me that the first picture shows vented disks, which is possibly why it also appears to have a different venting arangement fed to the disc centre (the correct way for these as mentioned by others).

Ian, nope the fluid still used to get hot using asbestos pads. I was reading a book last week which stated they used to suffer lots of gearbox problems at lemans as a result of using engine braking to preserve the life of the brakes.

If you do a google for 'brake pad design' or 'caliper design' I'm sure you will find loads of info on how companies are trying to increase pad pressure without affecting heat transfer. I did this a while ago when trying to find the best track pad for one of my cars, and got so confused I just brought what most people used in the end !

I think one of the big differences now is that pads tend tobe much harder, and so tend to wear the discs as much as the pads.

As you say, maybe I should stop thinking now too [img]/ubbthreads/images/graemlins/wink.gif[/img]

Cheers,
John.

[Bill Musarra]

Has anyone tried using brake recirculators??? In the book Brake Systems by Mavrigian and Carley, they talk about using recirculating systems to help keep the fluid cool as a fresh supply of fluid is delivered to the caliper each time you depress the pedal. It has the added benefit with road racers and endurance racers in that when it comes time to change the pads/calipers due to excessive wear(piston lock up), the usual method requires bleeding the brakes. But with a recirculator, you just change the caliper, pump the brakes two or three times and it self bleeds the line because the fluid is recirculated back to the recirculator and at most just needs topping off with fluid. There is a picture in the book showing the system but I don't want the copyright gods to strike me down. It basicly has a T fitting at the master cylinder or two banjo fittings stacked. One line goes to the caliper as usual. This passes through a flow valve(Wilwood) and hooks up to the caliper as usual. Then where the bleeder valvle is, is a line back to the master cylinder T, which also passes through a flow valve. This keeps the fluid flowing in one direction(a circle). I can send pics to anyone interested. I have read that recirculators are not considered good for street use, although I don't see why not.

Bill

[Ron Earp]

Yes. We had them on Jeff's TR8 due to huge brake overheating issues. I've got a special valve in the garage that handles this and makes it work very well, you can post it as it is common knowledge.

Did it work? Well, yes and no. It did the job, but that fluid recirculation was not enough to get the heat out of the calipers although the fluid was nice and fresh! So, while the fluid was fresh it still got scorched due to heat build up. More ducting was the answer for the problem. we pulled it off when we re-did the lines and ducting, didn't put it back on since we didn't feel it really added anything but complexity - one more thing to fail and ruin a race. I suppose it might be needed for long enduros, but the longest race the TR8 will run is 1.5 hours.

R

[Bill Musarra]

Here are the pics. If this is not acceptable, please pull it.







Sorry about making them so big, but I wanted you to be able to read the print.

Bill

[Ian Anderson]

Rear duct T70 from Lemans classic last year really basic!

[Kalun D]

www.bakerprecision.com

brake ducts that maybe could be adapted including NACA type

http://www.bakerprecision.com/brkduct.htm

[Gary Gibbs]

pegasus racing and truechoice also have several types of inlet ducts, etc.