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Thanks guys!
Moving on to the front brake duct cooling system.... The Baer brakes are large by huge 14" rotors with 6 piston calipers. The rotors are the curved vane type which are designed to move air from the rotor hat through the hollow vanes in the rotor to cool the rotor as long as it's turning. I want to have additional cooling ducts to aid cooling for several reasons. A. The aero changes I'm making will reduce the air exchange in the wheel wells. So that might contribute to the rotors, pads and calipers heating more than without the aero changes. B. I'm running 285 front tires on 18" X 10" wheels that just barely clear the calipers. So the calipers and rotors are kind of shrouded by the wheels which might reduce cooling. C. With the Yokohama AO 48 DOT R sticky tires I can brake harder during threshold braking before lock up than I would be able to with higher tread wear tires so more heat is generated. D. Keeping the rotors and pads cooler should extend their life. E The car is is stock bodied with no lightweight fiberglass or carbon fiber and propelled by an iron headed Pontiac engine so at 3500 lbs + it's no featherweight race car, yet I'll treat it like one on track. Here's the basics of what I've done. 1. Remove the speed sensor mount to open up more space for a 3" brake duct hose. 2. Make backing plate for the rotor hat that has minimal clearance with a tube to attach the hose. 3. To attach the backing plate I used a threaded boss in the spindle (supplied by Baer with their package) and drilled then tapped two bolt holes in the caliper abutment so the backing plate has three bolts holding it. 4. Modified a couple dashboard vent ducts from mid 80's GM trucks so the 3" brake duct hose would fit on them. They're slightly too big for the duct hose stock so a few V cuts and they can be squeezed just enough to get the hoses on. 5. Mounted the duct opening vents in the core support up high right next to the radiator on each side. This is a high pressure area behind the grills which isn't affected by the bow wave at the very front of the bumper or air dam. I'd originally planned on using the park/turn signal openings however a discussion with Ron Sutton about the bow wave influence and the reduction of pressure on the splitter just below the signal opening caused me to change plans. 6. I've built everything using 3" 300 degree brake duct tubing. It's a tight fit by the outer tie rods and sway bar ends snaking a 3" tube in there with such wide wheels/tires. I checked turning radius, suspension travel considerations, and such but I may find that I need to downsize to 2" tubing. So I'm going to test with the 3" and if all's good make a prettier set of backing plates welded instead of riveted. If there's clearance issues I'll move down to 2" ducts and add inline fans. Here's the pics! Spindle with speed sensor mount in pic below. http://i240.photobucket.com/albums/f...psrjoqy6rx.jpg Speed sensor mount removed (but opposite spindle). http://i240.photobucket.com/albums/f...psnfvxbq5d.jpg White line in pic below shows how much of the rotor hat is blocked by spindle arms, caliper brackets, and abutments. http://i240.photobucket.com/albums/f...ps1aslc5cq.jpg |
I wanted to seal off the openings on the top of the cowl where fresh air enters. This will increase air pressure on the top of the cowl so I'll get more down force in conjunction with a new hood to cowl seal which will be installed after final paint. I decided to use a reproduction screen I already had and modify it to seal off the openings. I used 3/32 EPDM rubber sheet and it's held in place with # 10 - 5/8"Phillips pan head screws and nylock nuts with 3/16" body washers to spread out the clamping force. The higher the air pressure, the tighter the seal will be. The car very rarely ever gets wet so I'm not concerned too much with drainage but if I'm on a trip and it rains I'll just pop the screen out.
Here's the pics! http://i240.photobucket.com/albums/f...psttzxlneu.jpg http://i240.photobucket.com/albums/f...psdymqh7os.jpg http://i240.photobucket.com/albums/f...psaqwvw0ce.jpg http://i240.photobucket.com/albums/f...psebvhimkx.jpg |
Continuing my efforts to manage under hood airflow and pressure I wanted to seal off the inner fender wells above the frame. The stock inner fenders have a factory installed "splash shield" which helps separate the air in the inner fender from the engine compartment. I wanted to take that a step farther. So I made up some patterns and used 1/8" EPDM rubber sheet to more effective seals. I'm going to be running the modified stock upper control arms for a while after reassembly but plan on eventually switching to upper and lower arms that will allow more positive castor and negative camber so I'll need to reconfigure the seals. With that inn mind I'll be using threaded hardware to hold the seals during assembly after paint now but may use pop rivets to save a little weight when the tubular arms are installed.
Stock splash guard in pic below. Note the gaps to the inner fender well not only around the control arm but also where there was no stock shield between frame and inner fender. http://i240.photobucket.com/albums/f...psvv9h3ux2.jpg Pics below show pattern making and the new seals in place. http://i240.photobucket.com/albums/f...pshwsa9axw.jpg http://i240.photobucket.com/albums/f...pszu3fo1iv.jpg http://i240.photobucket.com/albums/f...psdxmtqtsj.jpg http://i240.photobucket.com/albums/f...psgyzwmeqk.jpg |
The inner fender extensions on the 70-73 birds rusted out pretty easily and over the years I've seen a lot of cars missing them completely. It's a part some might just consider part of the crash protection crumple zone or be considered more of a splash guard. However it's also a part that affects aero. Without it the air coming under the front air dam collides with the air in the wheel well and seeks a place to go. I believe that the air will flow through the opening into the area behind the core support.
Twenty five years ago when I first built the car reproductions weren't available and I didn't really have a way to make replacements. I cut off the bottom of one of them because the rust had eaten it all up while the other had rust holes but wasn't as bad. Eventually I got a better (but not great) set off a parts car and planned on installing them.... Ya, never got around to that, and they disappeared along the way. Reproductions are available now, but I have the ability to make them so I did. If it was a customer car I'd have installed repros because of the fabrication labor time, but since it's my car I made them. http://i240.photobucket.com/albums/f...ps1slxm8yg.jpg http://i240.photobucket.com/albums/f...psct2kaqvr.jpg http://i240.photobucket.com/albums/f...pszbemqha6.jpg http://i240.photobucket.com/albums/f...ps2wbwxhca.jpg |
The core support of the early 2nd gen birds had a lot of gaps on the sides and top as well as large openings for the bumper supports to pass through it. I wanted to seal these areas off to keep the air out which should reduce under hood air pressure and increase the difference in pressure in front/back of the radiator which will help the radiator be most efficient.
Now those of you with early 2nd's might go look at the car and think pffft there's only an inch gap here and there and the holes for the bumper supports. However even though they're not directly open to the front of the car the cavity between the core support and the bumper/splash pan is one of (if not the) highest air pressure areas on the car. So the air is trying to get past the core support through the gaps as fast as it can. This is the same principal of why the brake cooling duct openings are placed in the core support rather than on the splash pan. So how big are the gaps really? I added them all up, then recalculated thinking I must be wrong but no.... Imagine a hole this big in the core support letting air in! http://i240.photobucket.com/albums/f...ps0p3djf7f.jpg The bottom of the core support is bolted tight to the lower edge of the splash pan sealing it. So the sides, top, and bumper openings are where I needed seals. To seal the sides and bumper holes I used 3/32 EPDM rubber sheet and pop riveted it in place. 3/16" aluminum rivets with 3/16" body washers. http://i240.photobucket.com/albums/f...psogxtjqrc.jpg http://i240.photobucket.com/albums/f...pslkdr0i3b.jpg http://i240.photobucket.com/albums/f...psfeey0euo.jpg http://i240.photobucket.com/albums/f...ps1zv3uuom.jpg To seal the top of the core support I used the same rubber but with plastic push pin fasteners for a more finished factory look. All of the seals will become tighter as air pressure increases forward of the core support with speed. http://i240.photobucket.com/albums/f...pspdcspzhy.jpg http://i240.photobucket.com/albums/f...ps268td2lo.jpg |
Very nice work and documentation.
I agree with your position on airflow and the core support / radiator. I hear far too many cooling complaints from people who go for the complex and overlook the simple (and sometimes inexpensive) in this arena. Most older cars have terrible aero - especially through the radiator. For years I have argued controlling airflow through the radiator is paramount for proper cooling. Anyone who doesn't agree needs to take a quick look at the OEM's. Any vehicle built in the last 10 or more years has excellent flow through the radiator with little or no traditional grille opening. It's not magic (unless you refuse to understand), it's called science. |
Yup, being in S. FL I hear it regularly. As you said, it's not magic.
On to bringing this thread up to date...... G braces have been around since Herb Adams & his crew were racing 2nd gens back in the early 70's. The basic brace idea itself was/is a good concept which triangulates the front sub frame to the upper cowl. This reduces deflection of the stock sub frame and stiffens up the overall platform so suspension and steering components can do their job better. The Pro-Touring F-Body Gen II adjustable G-braces shown here evolved from the simple early braces and are a great product. They're a very stout design with a nice adjustable feature that allows them to be easily installed on most 2nd gen F body's. The braces are actually much stronger than the cars they're being installed in and that is the focus of this post. By modifying the points where the forces transferred by the G-braces act on the cowl, upper control arm mounting bolt, upper control arm mount, and sub frame we can make the G braces function even better when the car is pushed to it's limits. In my opinion G-braces should only be used on cars with solid body mounts as a minimum, and preferably have sub frame connectors also. Doing any of the modifications discussed in this post without solid body mounts is a waste of time and money (even if you think it looks cool). Additionally, if you're not really pushing the limits of the car at auto-X, hill climbs, or on road race tracks it's doubtful the benefits of most of this additional bracing would be noticed. However I do believe the upper control arm bolt support would be a good addition to any car with any type of G-brace that uses the upper control arm cross shaft mounting bolt as the G-brace lower mounting point. So here's my list of areas that can use a bit of improvement and what I've done. I hope this helps for those who might want to copy what I've done or come up with better ideas. As with most things the evolution will continue. Also for those wondering, Dave at PTFB has been kept in the loop while I was designing/prototyping all these things. You can expect a new bolt on center upper G-brace to cowl support to be available from PTFB very soon (edit: available now). Where the ones shown below only fit low valve cover Pontiac set ups the PTFB one's will fit multiple applications for those with tall covers, LS engines etc. 1. Upper cowl where G-braces attach is three pieces of sheet metal spot welded together. The G brace mounts are almost centered on the large air openings on the top of the cowl which are the weakest areas. Also the drivers side G brace is in the area of the cowl recessed for the windshield wiper motor allowing more flex in that section of the spot welded ledge the brace is mounted to. Improvement 1. A strip of steel plate above and below ledge creating a sandwich and bolted through the pinch welded area. Stiffens the ledge and spreads the force from the brace over a much wider area. Creates a wider thickness for shear forces transferred through the bolts to act on by doubling (or rmore) the thickness of the ledge. Provides a strong section in the center of the cowl ledge where the top of the cowl is stiffer for the additional centered mount triangulation braces I made that do not come with G-braces. The additional braces also provide lateral support. I used bolts but the sandwich plates could be welded in place. 2. Stock upper control arm mount is made of 3/16" steel. It can flex and those of you who've examined them probably noticed that they've deformed over the years a bit around the forward UCA bolt hole from bumping parking blocks, tightening during alignment, or whatever. If your car's apart put a straight edge on the UCA shaft mounting face and you'll see what I'm talking about. The stock UCA bolts were splined for an interference fit. Often on the cars after many years the interference fit has been widened by movement and the splines don't engage tight any more. Improvement 2. Weld a piece of 1/8" flat plate to the face of the UCA mount. Most of us with track cars are already running a bunch of shims on the front and rear UCA shaft bolts to get as much positive castor and negative camber as we can. The 1/8" plate eliminates one shim front/rear and eliminates one surface where things could slip/move.. The 1/8" welded plate increases the thickness of the mount to 5/16 which is a 66% increase and stiffens the mount. Additionally it gives a thicker more solid base for larger splined UCA shaft mounting studs/bolts. 3. The stock UCA shaft bolts are 1/2" with a small splined base. Their intended use was to clamp the UCA shaft to the mount and accept forces applied in compression and tension. They were not intended to receive shear forces trying to wiggle and tip the bolt. With G-braces the shear forces applied by the braces are at roughly 90 degrees to the bolt AND the force is not at the base where the splines are but away the thickness of the shims and control arm shaft so leverage is involved increasing the possibility of tipping or wiggling the bolt. Improvement 3. ARP 1/2" studs with a wide spline base to replace stock UCA shaft bolts. The wide base makes the bolt more stable and spreads force over a bigger area. The spline area is also deeper which combined with the additional thickness provided by the 1/8" plate welded to the mount keeps the bolt more stable. The studs are also longer (cut to length later) allowing shims etc. to run a lot of negative camber and distorted thread locking nuts will be used to prevent loosening. The ARP long studs are stronger and also allow space to utilize an additional support for the stud to transfer force to the frame horns ahead of the UCA mounts. Additional improvement. Adjustable UCA bolt brace between the front UCA bolt/stud and the frame on roughly the same angle as the main tube of the G-brace.. This support transfers loads from the G-brace to the front frame horns reducing the load on the spline section of the UCA bolt by providing additional support on the other side of the G-brace to help prevent tipping or wiggling of the UCA bolt/stud. I feel this is the most beneficial modification and recommend it to anyone using any style of G braces that use the UCA mounting bolt as the lower attachment point. Pic below is an overview showing everything mocked up but not yet fully adjusted and tightened. The sub frame will need to come out for paint after other modifications are done. The bolts and nuts are all serrated flange locking fasteners excluding the ARP studs & grade 8 nuts used for the UCA shaft mount. On the cowl, the top of the G-braces are fastened with 7/16" bolts and the other bolts (including the additional upper braces) are all 3/8". The lower supports for the UCA bolts are fastened to the frame with serrated flange nuts/bolts. Edit: Most of the items shown in this post I've been selling on the TA forums etc. and started a business called Lab-14 to sell them and other products. No website yet but soon. http://i240.photobucket.com/albums/f...psyyvci1im.jpg Pic below shows the 1/8" thick plate welded to the UCA shaft mounting surface. Note the thickness where the splines of the stud will hold the bolt more securely. http://i240.photobucket.com/albums/f...psqaihegpg.jpg Pic below shows the difference between a stock mounting bolt for the UCA shaft and an ARP wheel stud used to replace them. You can see how the wider deeper spline section will support the bolt more rigidly. http://i240.photobucket.com/albums/f...pshozi0tbe.jpg Pic below shows how the additional upper supports are attached to the PTFB Gen II adjustable G-braces and the angle of the lower support that is attached to the UCA bolt and sub frame. http://i240.photobucket.com/albums/f...psqojkvh2v.jpg Pics below show the drivers side lower support. The unused mount on the steering box has to be cut off to provide clearance for the mounting bolt through the frame. Everything's close but fits. Careful marking of where the frame mounting bolt hole needs to be is critical on the drivers side. Passenger side there's plenty of room. http://i240.photobucket.com/albums/f...ps0ropnunl.jpg http://i240.photobucket.com/albums/f...psgrgy5mkp.jpg Pic below shows all the pieces used for the upgrades described that do not come with a set of PTFB Gen II adjustable G-braces. http://i240.photobucket.com/albums/f...psnih6odon.jpg |
With everything mocked up and the last welding done to the sub frame I sandblasted it. Followed the blasting by shooting it with epoxy primer then regular high build primer followed by sanding then gloss black acrylic enamel.
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When I had the roll cage in my car fabricated 7-8 years ago I removed a lot of the interior, took the car to the fab shop where they built the cage, and then I painted the cage and reassembled the interior. I spent a lot of time trying to mask off the dash, headliner, and other interior bits that hadn't been removed so I could spray the cage. I found it extremely difficult (OK impossible) to get everything masked off and try to figure out a way to spray the cage with the windshield and rear window in the car. It just couldn't be done. So I ended up painting the cage with a brush Using PPG DBI (base coat with activator) then sanding the brush marks smooth, then sanding, then painting, then sanding, and painting again until I had several coats on. The DBI is for use without a clear coat. It came out fine overall but it just didn't look the way I envisioned at the start. There were brush marks and other little things I'd notice that bugged me although probably no one else ever noticed with all the roll cage padding etc. in place.
Since I've got everything out of the car except the headliner (bow type), shifter, and some wires this was the time to spray the cage since the dash windows etc. are all out. So I sanded down the previously applied paint and shot it with the same color PPG Deltron Silver Frost base coat followed by PPG Global Matte clearcoat. For those of you who've never painted a cage, it sucks. I don't remember it being any easier when I was 40 years younger and although I'm still slender and agile, a contortionist I am not. However the cage came out the way I wanted it to the first time and I'm happy with the results. http://i240.photobucket.com/albums/f...pscsrxrkno.jpg |
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