Spec7 brake ducts?

R

Rex B

New member
I'm about to fabricate some cooling ducts for my '85 in preparation for the 1st SCCA race at Texas motor Speedway July 12-14. Rather than go the easy way and get the Mazda Comp backing plates, I'm going to do it the hard way.

Caliper end - Looks like I can weld a 3" tube at about a 45-degree angle off the stock backing plates and then open up the stock holes.

At the front the stock black sheet metal "duct" is already opened. I intend to attach the hose there with some wire stitching and fill the gaps at the outboard end with spray foam or something similar.
Ideas or suggestions, caveats before I get started?

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Rex, take the easy way out & do the job once.
smile.gif
Cooling the caliper is the second half of the cooling job IMHJ. Air restricted/forced to the center of the rotor & vented through the rotor webbs is getting the cooling air to the primary source of the heat. Rotor/pads is your heat source & by cooling the caliper body, that coolness from the caliper body must be transfered to the pads.
frown.gif


Also at the air intake, purchase some ducts to gather the incoming air & it gives you a place to attach your 3 inch tubing to. I presume you have the front valance with the stock air loover intake slots.



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Have Fun

David Dewhurst
CenDiv Milwaukee Region Spec-7 #14
 
What you had said sounds good as to placement
but as to the cooling of the pads transfer heat to be cooled does not seem to make sense.I my self would be concerned with the rotors.Also duct tape can help reduce any chafing good Luck Texas sounds realfast and fun.Watch out for the jackOlops.
 
David
Are you saying that I should also run hose to the caliper body? If so, I can't since I'm limited to one hose.
Also, I've looked at those fiberglass NACA ducts and similar designs with an eye toward sealing the "gills" and giving me a hose connection. I have yet to find one that will clear the fender support, which we are required to keep. I think I can seal off that black steel thing pretty well though.
One thing did occur to me: The OE setup uses a thin steel shim between pad and caliper/inside pad and caliper piston. Normal practice among the local guys is to discard those along with all the clips and such. However, I think those pad backing shims will do a lot to isolate heat at the pad and keep it from transferring to the rotor. I took them off the other night, but I think I will replace them..

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In Pro 7 we are allowed tp remove the blinker assemblies for brake ducting. I went to Home Depot and picked up some plastic 3 into 1 gutter funnels and cut them to shape of the bumper. You would also need couple of 45 degree attachments to get under the head lights. The 3 inch hose fits great. It's more work, but the instalation is clean and if you run over something there is less chance of ripping the hose apart. I hope this helps.

Eric
 
I see. We aren't allowed to go through the turn signal holes, only the front valance through the stock location. I may stop by HD and check out the gutter stuff for other ideas.

Thanks, both of you
 
Rex, in the CenDiv we use the SoPac rules exact as the SoPac does.

One 3 inch to each wheel.

GCR ITCS 14.1.4.D.6.b (partial, read the whole rule)forward direction only, & that no changes are made in the *body/structure* for their use. In the GCR glossary look up the word *body/structure*. I think I left the fender brace in place, I removed the metal piece that acted like a air direction duct & slightly modifyed the ducts to fit. Plus the fender brace & air duct is not directly *licked by the air streem* & the SoPac rules & the ITCS 14.1.4.d.6.b rule says I can add 3 inch air ducts....... The rules do have some you can't's but I have not worked against those you can't's. By using the loovers I am not changing the *body/structure*. Your going to wire stitch the duct, I use 4 # 10 bolts to connect the duct to the valancs/loovers.




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Have Fun

David Dewhurst
CenDiv Milwaukee Region Spec-7 #14
 
Here is how our rules read:

" Backing plates and dirt shields may be ventilated or removed. Air ducts (maximum 3" diameter) may be fitted to the brakes, provided that they extend in a forward direction only. 2 ventilation holes may be cut into the lower valance for the purpose of cooling the brakes. Each hole is not to exceed 33 sq inches in area (including the stock brake duct ventilation on later cars.) No material may be added forward or below the air dam."

Strictly speaking, this does not even allow the use of a fiberglass "scoop" behind the valance, or the Maxzda Comp backing plates w/hose provision. So all I can legally add is *hose* and fasteners, then modify existing parts.

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A 3" hole is approx. 7 square inches of area. Since your rules allow a maximum of 33 square inches you would think that the intent was to allow an off-the-shelf brake ducts to be used (like the one shown in the Honda thread). These are designed for 3" hose. They are available from Pegasus, or just about any circle track speed shop will carry them if there is one located near you. I think Butler is the brand name.
 
Well, after much deliberation and measuring, it turned out that the cheapest way is also the best, as far as I can tell.
I prety much followed the directs at
http://www.spec7.org/TechFiles/BrakeDucts.doc
This uses the stock front duct, 3" of flexible duct. The wheel end is loosely attached to the stock backing plate "scoops" with wire to allow it to swing out of the way. As inelegant as this sounded, there just isn't room for a solid attachment to the backing plate. Anyway, I'm almost finished with it and it looks like it will work out.
One thing I did different was in the way I attached the hose to the front OE ducts, behind the valance. I flattened the round hose enough fit tightly into the inboard end of the duct, which had been expanded to the max. I then used expanding foam to fill in the gaps outside the hose, within the scoop. Once it sets I'll trim it and paint it all black. Once installed, I'll look at sealing the scoop to the valance, although I don't think that's critical - it's already a good fit.
Thanks for the help guys. It was very useful to run through all the possibilities before settling on a design.

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Rex, this post is NOT DIRECTED AT YOU. I would bet that if you looked at some of your Spec-7 RULES CREEPING counter parts down your way that you would find that they have Mazda Comp ducts to the center of the rotor including thre NASA ducts implemented behind the valance........
wink.gif


Enough said on this subject by me

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Have Fun

David Dewhurst
CenDiv Milwaukee Region Spec-7 #14
 
David
IMHO there is way too much acceptance of illegal mods. Some of this came from the first years, when the guys that actually wrote the rules took a very liveral interpretation of those rules. They have all moved on to other classes now.
Then we have the new racers entering SCCA racing for the first time. They are full of enthusiasm about building their first race car. Invariably they see all the things that could be done to make it a little faster or a littler "cooler". When they realize the mod is illegal, they immediately propose a rules change. We go through 3 weeks of debate and usually leave the rules alone.
It's really sort of amusing to see the same topics come up every year, each time by people new to the sport. It's also tiresome convincing each new wave that it's a bad idea.
Im against any rules changes that add expense, even if it's optional. If it's optional, it soon becomes mandatory to be either competitive, or to maintain a high resale value for the car.
I got into this class from FC and ITB so I could stop wrenching and go racing. The only reason I'm adding brake ducts is because I think TMS will be harder opn brakes than any other course we have run. Fortunately there are enough people who share this view to keep new rules to a minimum.
One thing that is worth noting though: The top 5 drivers have the most legal cars in the group. It's the new guys midpack or back that bear watching. And if any of them start finishing ahead of me with an illegal car, I'm not above being the bad guy and filing a mechanical protest. There isn't enough of that happening to keep the class clean.



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Rex, your latest is a very intresting post (as you know from my past posts on Southwest site I do not CREEP) because from an older memory (mine) I seem to have read that the group down your way have basterdized the original Spec-7 SoPac rules. If that is a correct presumption why is anyone there concerned about improving a safety issue. Readly available top notch BRAKES......that work with the first pedal push. My previous description of brake ducts including the NASA intake ducts is what the SoPac people use. They is those that started the Spec-7 race class even tho there is another un-named person from I beleive down your way that likes to try taking credit for starting the class. SoPac's Mark Holland & Dave Turner 1994.

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Have Fun

David Dewhurst
CenDiv Milwaukee Region Spec-7 #14
 
I'm not acquainted with Mark Holland (is he related to Bill?) but I do know how Dave Turner's mind works. He and I "invented" Improved Touring for Solo I in the early-middle 70s. The actual philosophy was, "Production classes are too professional, Showroom Stock is for cars no one is interested in. Give the folks a chance to race what they drive on the street." It took a little diplomacy and some serious cooperation from SCCSCC and SCCA, but it finally flew.

The rules were approximately: Current safety equipment, Showroom Stock specifications plus exhaust and swaybars free, rims of standard diameter up to 7" wide, DOT tires a size larger than stock ("DOT" meant something a little different back in the day). That was about it.

Within a year IT was the biggest category in So Cal Solo I. All _kinds_ of people put rollover bars in their cars and went fast on the big racetracks.

There were cheaters, and the good guys beat them with skill and attention to detail. Sound familiar? Rules evolved. Competitivity got expensive. I missed the episodes where someone somehow decided if it was good for Solo I it must be good for racing, but here you are.

Everyone has an ox and an axe. Some of them are going to get gored and ground, and it takes effort and interest by each to determine where the blood will flow and the chips will fall. That's the way the world works.

Frank Sheffield
San Diego CA
USA
 
Frank, I don't have a clue with reference to a Bill Holland. The only reason that I know of the Mark, Dave & Spec-7 connection is because back in 1997 I was looking at H Production & meeting some regular National drivers through a friend National driver & learning what ($$$$$$$) was going on. At the same time I was keeping an eye on the SoPac & DC Regions with their Spec-7 class & costs. I still have an article that was a feature in Sportscar on the Spec-7 clss with the orginators beeing Mark & Dave. I have never meet or talked with Mark but I do business at Dave's place. Purchased some stuff through Steve Coe when he was at Dave Turner Motorsports. Have talked to Dave a couple times.

Being that this would be my first venture into car racing at 55 years young at the time (in 1997) I decided that I did not need a 40 year old 4 cylinder hand gernade worth $10,000 with a rebuild at approx 4 weekends if the friken motor lasted that long. I swere some of them bleed to death. Opps, I mean bleed oil to death. The Mazda/rotary was an excellent decision. Economy & more economey........ is how racing a rotary is described.

Good info you passed on. I always enjoy some factual history of what went on in the SCCA before I got hooked.


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Have Fun

David Dewhurst
CenDiv Milwaukee Region Spec-7 #14
 
"group down your way have basterdized the original Spec-7 SoPac rules. "

I think that's a little strong, David. While I would have preferred to have a standard set of rules across divisions, SCCA failed to take the lead then. Heck, even Spec Miata is not standardardized 100% - you can run without a hardtop in RMDIV. And DC Spec7 rules are different from SoPac. Big deal.
Were I king, I'd have had the rules uniform, but....
I actually tried hard to get us to go back to stock alloys, to no avail. Everyone had spent the $ on 7" wheels.

"If that is a correct presumption why is anyone there concerned about improving a safety issue. Readly available top notch BRAKES......that work with the first pedal push. My previous description of brake ducts including the NASA intake ducts is what the SoPac people use."

And those are legal here. I posted a question because I was unclear, and we discussed it. However, the GCR definition of "duct" is so broad that almost anything between the valance and the backing plate is free, as long as OE parts are not removed, and the duct is no bigger than 3" at it's smallest diameter.
I am a liitle curious about your intense interest in our SOWDIV rules. You aren't in SOWDIV, are you?
 
Rex, as I had posted earlier with RULES CREEP. The comments are NOT DIRECTED AT YOU. Everything I have read on the 7 site you personaly support holding the mustard, ketchup & leave the rules alone. The DC Region has three or four rules items that do not agree with the SoPac rules & none of their changes directly affect speed or handling. The Rocky Mountain Division has three items different than the SoPac & they do not impact speed or handling. The CenDiv rules are dead nuts tha same. The Southwest's bigest rule change that puts you all outside the SoPac box are your headers. That one rule basterdization (& there are more) makes the Southwest Spec-7 cars faster than any other division/region in SCCA. CREEPING RULES within the SCCA is how some of the H Production cars got to be $50,000.00. Ya ever lay your eyes on the cars of Huffaker, Hussy & a couple others ? How about a front E Production car that starts at $50,000.00 & goes from there upward ? It's all RULES CREEP from the 60's to today. Do we want 20, $30,000 Spec-7 cars in 5, to 10 years. How about a $40,000.00 SpeedSource ITA car ?

I don't want any region to CREEP the RULES & drive UP the cost. As I have said on other sites, if people want to play with rules on 1st gen Mazdas outside the Spec-7 SoPac rules please get out your check book, step up to the plate & step up the ladder.

Spec-7, ITA, E Prod, GT, take your choice.

Rex, I think I have answered your questionS in all sincerity.

Here is a serious question for you.
Earlier in the year on the the Southwest 7 site you folks were talking about going to the ARRC to race Spec-7.

Do you think that it is fair to the Spec-7 drivers who have stuck very close to the SoPac rules & have done nothing with the original SoPac rules (such as adding headers) to increase their speed to let the Southwest cars race in the Spec-7 class ?

You folks are to fast for Spec-7 & you will basicly never keep up in ITA. The floks around most of the country feel the same way about the CRX being in the ITA race class as I feel about the Southwest Spec-7 cars being considered the same as the the Spec-7's in the remainder of the country.

My vote would be you folks shall not be in the Spec-7 class at the ARRC. You shall be in the ITA class.

Again Rex these comments are not directed at you. They are directed at those within the Southwest Region that CREEPED the Spec-7 rules. Your Region rules are outside the box so in IMHJ don't expect to play within the box. (at the ARRC or any other inter regional race outside the Southwest.)

That should be everything I have to say about this subject & I will never slight you again by bringing up Spec-7 RULES CREEP.

Everyone have a Happy & Safe 4th.

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Have Fun

David Dewhurst
CenDiv Milwaukee Region Spec-7 #14
 
As a followup to the project, I had attached the hose to the front scoops as I described above. Once the foam had hardened, I trimmed the excess with a hacjsaw blade, then painted it all black. Turned out real nice.
At the brake end, there are cutouts in the backing plate with little scoops attached. I drilled 4 holes in the scoops - one at each end, two in the center. I threaded some safety wire through each hole, then through the edge of the duct hose so to capture two coils of the reinforcing "slinky" wire. 3 more hose in the outer lip of the backing plate, attached the hose there also.
Then I remounted the wheel and checked for clearance. Hose routing is difficult, but I think I have it set so it won't get hit by the wheek. We'll see what happens when I get a loaded outer wheel in a hard turn. TMS should test the full range of motion.
BTW, I intend to write an article on the first SCCA Reg/Nat at Texas Motor Speedway. Watch for it in SportsCar.
 
Followup - ducts worked out fine, no wheel interference, pads got plenty hot but not too hot. The ducts even survived a 90 mph trip through a tire wall, which is more than I can say for the bodywork :/

Good event at TMS though. We need some more IT entries for next year so we can lobby for more track time.
In the meantime, there's a Double Regional at Texas World Speedway on the 2.9 mile course. If you haven't sampled it, this even will be worth the trip.
 
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