Brake Ducts

[Ron Earp]

Well, it isn't a GT40 or Lola, but they are some brake ducts for our TR8 race car. We've have chronic brake problems on this car like you wouldn't believe. So, now we've got a rotor hat that will feed air to both sides of the solid (yep, have to run it) rotor and this duct I made to feed air into the piston/pad area.

We're racing in SCCA IT, and in this class we have to use stock brakes. We're running 13" wheels so there is very little room around the caliper to get some air in there. I'd like to do up some wheel fans too, but I don't know much about making them. Time to learn.

These little jokers took a lot of time to make - lots of cutting out of card board, snipping, cutting, trimming, getting teed off, and starting over. I think they will work and they hold onto the calipers with the two pins that hold the pads in position. Already got some new designs for version 2!!! So, now you know where some of my time goes when there is no Lola progress...

 

[Alex Hirsbrunner]

Dang, snap a finish pad on one and you can paint the lola with them

 

[Sandy]

Ron, how would those work on non-solid disk? It's an interesting way to get some air on the caliper.

I have seen the vintage mustang guys that run the air to the center of the non solid rotor with a nice backing plate and a flex hose to it. I have wanted to do it to the mustang, just have not had and huge issues with brake cooling (read as not driving hard/fast enough!).

These are the one that cobra automotive sells and I think a bunch of the vintage shelby guys run them as well. Look pretty easy to make. Yet another project

http://www.cobraautomotive.com/Handling.htm


Sandy

 

[Jac Mac]

Ron,

Are you allowed to drill holes or mill slots in the rotor hub to allow cooling air to reach both sides of the rotor if applied from the rear. If so you could direct all the cooling air to the center of the rotor,then take a duct pipe from the caliper scoop you have made to a low pressure area to induce flow past the pads.

Large electric motors etc, sometimes have centrifugal type cooling impellers that may serve an air pump in your case.

Jac Mac

 

[Ron Earp]

Hey Sandy,

We have these too in addition, hats that go and blow air of both sides of the rotor as shown in the picture below off the site you referenced. So, each rotor will have two ducts going to it.

Jac Mac - we are not allowed to do squat to the rotors. Rotors must be as OEM. You can cryo treat them, but you can't drill them, lighten them, or use anything but the same style, size, and material of the original.

We are also putting some boat ventilation motors in the duct work to keep the air flowing at low speed and stopping in the paddock. Big problem we have is the brakes will hold up, but in the paddock they heat soak and burn the seals up - no amount of cool down helps (you only get two laps tops anyway).

Maybe with the new ducts and electric vent fans we'll be good to go. I think one of the big problems is the damn calipers (which we cannot change) and are those AP iron jobbies that weigh a ton. Once they are hot they stay hot for a long time.

Al, if those jokers will stand up to 500+ degrees then I just wasted a lot of time!!!

R

 

[Mark Worthington]

Dang, snap a finish pad on one and you can paint the lola with them

Now that's pretty funny. I think Ron like ducting his brakes more than he does body work.

 

[Russ Noble]

Ron.

Don't you find having to run totally unsuitable OE a hiding to hell? Why not get a better basic platform to start with? Like a Porsche?

BTW. Did you get my PM a couple of days ago re gauges?

Cheers

 

[Ron Earp]

Hi Russ,

I didn't pick this car, my buddy did. Nonetheless, if we can get the brakes working well he has a shot at pulling off some wins in this class. The top cars in this IT class, ITS, are the BMW 325i, 2nd generation Mazda RX7s, and the Nissan 240sx. Other "strong" cars in the class are the 300zx (SOHC version), and a couple of FWD Acuras I don't know much about.

If the proposal that Jeff and I put together for ITR, a class above this one, goes through then I'll be doing what you suggest in a couple years. We classed the Porsche 968 there and I think it'd be a very good race car platform, as well as some other strong cars in R.

All this brake stuff is good for me though, it'll carry over to my Jensen Healey which will have many of the same braking issues since they are basically the same. I'm sure we can lick it.

Ron

 

[Russ Noble]

Sounds like you're probably competing on a relatively equal basis with the other cars in the classs. Out here in classic racing you we are up against everything. Porsches, Cobra replicas etc are virtually impossible to beat. (No GT40's yet although I know of several almost ready to race. It'll be good to get out and join them.) However in the interests of safety, brakes are free. Nevertheless my 270x22 ducted, vented rotors were constantly being replacing due to cracking and warping. In one particularly torrid race I arrived at a tightening 2nd gear corner off the end of the main straight at about 130 mph and the pedal hit the floor. Boiled (race quality) brake fluid, no warning!

Good luck with your standard brakes!

That's why I love racing in the wet, when you're fighting an unequal fight it's the great leveller.

Cheers